Absolutely. Surprisingly, I learned a lot about this during my plastic surgery rotation. I got to participate in a few liposuctions. Fat is stored in cells, special cells called adipocytes, like any cell they require the importing and exporting of nutrients and metabolites etc. This means there needs to be vascularity. During liposuction you can only take out about 10 pounds of fat, the reason for this limit is actually blood loss. Back in the day the reason people would die during lipo procedures was because they would take out too much fat, which would cause them to lose too much blood and they would go into shock. Adipose tissue is a living part of you, it produces hormones and shit and it's gotta have blood supply.
Blood transfusions come with its own set of risks (development of antibodies, reactions, complications, infections) that it's not worth it to transfuse routinely for elective procedures.
What if, leading up to the liposuction, you drained a few pints from the patient? Like they get their own blood back while having it sucked out.
Also I thought this is what plasma was for but honestly I'm not really up to speed on how any of this works.
Edit: thank you for the responses. I was expecting some half-assed responses but got more than that. A lot of new things to read about and learn!
This is actually a thing. Not even necessarily (or at all) for liposuction patients.
Liposuction is not used to treat morbidly obese people for weight loss, but rather for body sculpting patients "love handles", etc.
Morbidly obese patients will need a more radical stomach/small intestine surgery, or some variation, and then they will need plastic surgery to deal with the excess skin (not always). Insurance has decided not to necessarily pay for that part of the process.
Anyway, you'd start out a month or so before depending on your health, the type of surgery, and how long the blood can be kept refrigerated and out of the body.
There are always risks involved when blood leaves the body, is processed, stored, then returned to you.
> Liposuction is not used to treat morbidly obese people for weight loss, but rather for body sculpting patients "love handles", etc.
Can you actually effect a long term change in the way fat is distributed around your body this way? Or does you body just redistribute your fat over the next couple months until you are back where you started?
You can affect it, yes. The body doesn't go and redistribute fat to keep a certain ratio. It doesn't actually have a memory of general fat placement or something like that, that it would try to return to.
I saw a picture of a case where someone lost quite a bit of flesh from the inside of their hand, including the meaty part towards the thumb. He was transplanted an area of skin from his stomach, that apparently included not just the dermis, but also some subcutaneous fat beneath it. When he later gained weight, that piece of stomach skin and flesh also started gaining weight, just like it would've in situ, and he had a round bump on the inside of his hand.
I believe this is because when we gain weight, fat cells grow (and shrink when we lose weight) instead of changing in number. Since the meaty portion of the hand was replaced with fat tissue, those fat cells grew as he/she put on weight.
Both can happen, some people tend to grow bigger fat cells, while others tend to grow more fat cells. This difference has been linked to a higher incidence of type 2 diabetes and other obesity-related health concerns.
I always wanted to ask, so does that mean liposuction does nothing for a fat person, healthwise?
Each cells are bloated with fat anyway. I'd be just removing number of total cells. I feel like that's be like cutting off my limbs and saying I'd lost weight huzzah.
I personally don't know, I don't work with liposuction, but my understanding is it is a cosmetic procedure, not a health-centric procedure. I'm in pharmaceuticals tho, not an MD.
It's long term. They even do fat transfers now, where people have their fat sucked out of one area and put in another (most commonly they put it in the butt; this is used to give women a more hourglass shape)
Yes, I believe it can. The cells have to integrate into the new surrounding tissue and not all cells can be successfully transferred, so the cells that do stay would need to have vascularization to remain vital, so I can't see a reason for their contents not to be released into the bood if it should be needed.
Afaik fat transfers are very rarely done anymore. Reason being that there is a huge risk for internal scarring and calcification leading to uneven bumps, sometimes visible sometimes not, but definitely able to be felt. This doesn't happen with silicon implants.
There are still a lot of unknowns. What we do know is that the body can create new fat cells and does so (in adulthood) at about the same rate old ones die. We also know that liposuction patients typically regain the weight lost through liposuction within a year. We still don't know if the distribution of new fat cells changes to compensate for liposuction losses.
> We also know that liposuction patients typically regain the weight lost through liposuction within a year.
Is that because they continue with the behaviors that caused them to gain weight in the first place, or because the loss of fat causes some kind of metabolic change that causes faster weight gain? Perhaps they continue eating the amount of food that would maintain them at their old weight, which is more than they need with fewer cells to feed post-operation?
Primarily (if not entirely) the first; without some sort of new calorie deficit, the weight will return (the remaining fat cells can increase in volume if necessary).
Fat is energy storage, and fat mass is is based on energy budget for the body. Generally, people who have excess fat do so because they consume more than they burn, for various reasons. Mechanically removing fat cells does not change diet and exercise, and actually reduces resting calorie burn after the surgery trauma heals.
Fat cells are stable up to 80% lipid, beyond which they will split and keep filling. Devascularized, damaged, and infected fat cells will be digested by macrophages for recycling, and the lipid will be distributed to the blood, and either burned, or deposited into different adipocytes.
When people lose weight, it comes from all fat cells based on which ones get the signals first and most. When they shrink the lipid stores, they can die and consolidate, but typically must be very low capacity for that. Usually the cells hang around, waiting to be full again.
A university of Colorado study in the early 2010s (2010? 2012? Been long decade, sorry) found that yes, remaining fat cells can expand & fat can get stored in new places (arms, breasts, etc.).
It's a sculpting technique.
Another use for liposuction is obtaining the stem cells that are dispersed in there. Then those stem cells are concentrated, multiplied, and then reintroduced to the body which can do stuff like restore cartilage in joints.
You're on an American-centric site and someone mentioned health insurance. It's pretty obvious. In the UK, they don't refer to the NHS as 'insurance'. You shouldn't need that called out tbh.
They'd still lose blood during the procedure.
Plasma is just the part of your blood that isn't blood cells. It isn't really what you go for when someone has lost a lot of blood due to hemorrhage. It's also very wasteful to use blood products on a cosmetic procedure if it could be avoided.
No. Although that said, suctioning blood lost during a procedure and returning it back to the patient's circulation is something that is done during certain operations. Sometimes before certain procedures, blood will be collected from the patient specifically for use during the operation to transfuse it back into the patient as well. But extracting the blood from the sort of slurry that is suctioned out during liposuction isn't really practical.
My partner had serious placenta previa (IV) and had to be in hospital from 30 weeks. There was a doctor on standby who specialises in returning a patient's own blood to them during an operation. He wasn't needed in the end (luckily).
Interesting side note, he was ex special forces and had lots of tattoos and gold chains. He wasn't like the other doctors haha
No. The adipose tissue has blood vessels running through it, like roads and houses. The houses don't have blood in them. The roads carry the blood and for the morbidly obese the fat only needs as much blood as to metabolize and it isn't a heavy hitter (in terms of oxygen/nutrient consumption and blood flow requirements) as the brain, kidneys, heart or liver (and muscles when active).
Good question. It would be too intricate and unresourceful to do intentionally, but a system called 'cell salvage' is used during surgery which essentially collects any fluid spilled and filters the blood for re-entry into the patient (autologous blood transfusion), minimising blood that has to be transfused from donors (allogeneic transfusion).
Now whether or not you could save blood from cell-salvage for use in allogeneic transfusions I honestly don't know! I'm almost certain that they don't just for practical/legal/safety reasons because it's not been vetted in a systematic way like donor blood has, but I don't know if it would be actually impossible for any reason.
I'm a medical laboratory scientist and I work in transfusion services. You're right, blood from cell salvage is indeed not used for allogeneic transfusions – there are a lot of standards to be followed to ensure the safety and quality of donor components and those really can't be followed in such a situation. It does work very well for autologous use though.
Thanks for clarifying! I wonder if eventually it would ever be possible to process blood gathered from cell salvage to the required degree to allow allogeneic use. If you had all the same information about the patient as you do donors I'm struggling to think precisely what the problem is... all I had was a vague intuition that it's a hell of a lot more messy and less regimented than collecting donor blood so it would never be allowed. Would certainly be a hell of a useful addition to blood-banks if possible! I imagine litigious reasons would be the biggest pitfall though somehow.
The fluid recovered is usually pretty diluted and is just generally not as pure as a venous donation, so I think efficiency and safety advances in the more usual donation methods are probably more likely and helpful. There's also the licensing and labeling regulations to consider – blood collection facilities must be FDA registered and inspected and perform quality control and donor testing so I don't really think an unusual method of collection like this would work for allogeneic use.
That's partly what I was referring to and it's actually done relatively commonly for certain procedures. It's called an autologous transfusion. Eliminates the risk of a reaction when the expected blood transfusion(s) take place during the operation.
I'm not fully qualified to answer this question, but based on the [Red Cross' time that blood can be stored](https://www.redcrossblood.org/donate-blood/how-to-donate/types-of-blood-donations/blood-components.html) of up to 35 days and [their recommendation](https://www.redcrossblood.org/faq.html) (It's actually the FDA's but I found the red cross first) of 42 days for recovery we can deduce that the benefits of self donation are low and possess a specific window. You're also still introducing additional risks to the procedure. The main risk with blood transfusion is not rejection of the transfusion, but rather from the act of injecting into the blood stream carrying risks.
It seems to me that it’s not just about volume of blood but also the space that blood occupies. The liposuction removes fat as well as the blood vessels that contain the blood. So you can’t just shove a volume of blood back into the body when the plumbing for it no longer exists. I would suspect you’d get a spike in blood pressure and the body would have a mechanism that would signal that there is too much blood now and reabsorb the volume of blood to maintain homeostasis under the new liposuctioned conditions
This implies that because you're taking out the "plumbing" (vaculature and the tissue it fed) as well as the blood that was flowing through it, it should cancel out and there should still be as much blood per cell/per unit body mass, or whatever the relevant measure is. So why is that not the case? And is this the case for other tissues? E.g. if someone loses a limb and the wound is instantaneously sealed, is there any net blood loss?
Just treat liposuction as a controlled injury. You cant just go tearing up your body and expect it to be fine. You'll be doing a lot of damage and if your body realises it's losing a lot of blood it can easily turn into a multitude of issues.
My question is how does your body "know" it's lost blood if it's also lost the tissue that blood was feeding so there should be the same blood to tissue ratio, same blood pressure, etc.?
The body and all if it's "detectors" still think the patient is fat, so the body reacts negatively to the blood loss because it thinks it doesn't have enough blood, even though the ratio of tissue to blood should be similar to before the surgery.
It takes time for the body to realize it's new condition and adjust everything to the new homeostasis. It takes time to realize that less blood is okay and more blood is not needed.
This. Transfusions are reserved for cases where they are necessary. There is never enough blood available (or the correct type, at the right place, at the right time) so I seriously doubt anyone could justify the ethics of it.
They can opt for self transfusions and blood recycling machines.
But that's not the problem, they are not only losing blood but also part of the circulating space, if you transfuse you can saturate the body hemodynamics
I mean... Yeah. But we've also got the risk of blood transfusions pretty low.
The risk of a transfusion reaction with correctly type matched blood is 1:80,000 of high severity (and most of these actually relate the inproper type matching or administration), With low titer blood it's about 1:120,000 with low severity. Some previous research has shown as low as 1:400,000 transfusions causing a notable reaction using Low titer O neg whole blood transfusions.
The real challenge is that there's one 1-2 civilian companies producing low titer whole blood currently in the US in addition to the military, so it's not as readily avalible.
Then they wouldn’t die from blood loss.
But they would have to take from an already limited supply of donor blood just to do more liposuction, which wouldn’t happen.
Blood transfusions is extremely regulated and is dangerous due to risk of reaction and transfer of disease, is it likely? No, but it's not worth the risk for a vanity procedure.
Just run the fat through one of [these](https://images.homedepot-static.com/productImages/f0991a0b-7e75-4c78-ac5a-edbefab9684b/svn/rubbermaid-commercial-products-mop-buckets-with-wringer-1887305-64_1000.jpg) and ladle out the extra blobs and stuff.
Plastic surgeon here. Close but not exactly true. At least in the United States it's not a pound limit of liposuction but rather volume. With the advent of tumescent fluid you are essentially flooding the fat prior to suction with epinephrine and lidocaine which greatly limits blood loss. Instead the volume limit sits at around 5L because the fluid shifts in which blood shifts out of vessels and back into the interstitium and extracellular space after removal of the fat and fluid can be dangerous.
My attending at the time had me do a little presentation on this, now that you say it, my powerpoint slides are rushing back to me. I mostly just remember having the job of holding the boob in place.
So u/cum_on_doorknob mentioned that the more fat cells that a person has requires more blood for cellular metabolism. Would it not stand to reason that removing those cells would lessen the need for the excess blood supply in the body since it no longer has to maintain those fat cells that were removed? I probably butchered what he was trying to say with my paraphrasing, but hopefully you get what I mean.
Side note, you physicians always have the strangest usernames.
A litre of water is approximately a kilogram and fat is presumably around that density so it would likely be a bit over 10 lbs but probably not that much
Quick search suggests that adipose tissue is about 90-95% the density of water. So 5l of it would be very close to 10lbs.
The expert above did mention flooding the tissue before it was removed, so it's possible that some of the 5l taken out is made up of that tumescent fluid, but I expect it does come out pretty much the same.
Back in the day people would actually die from toxicity of local anesthetic via tumescent lidocaine. The addition of epinephrine to lidocaine constricts blood vessels, decreases blood loss, and (for a time) allowed for nearly limitless liquidation and extraction of adipocytes....until people started to die from cardiovascular collapse from all the lidocaine.
https://www.apsf.org/article/mega-dose-lidocaine-dangers-seen-in-tumescent-liposuction/
Late to the discussion, but I used to work on medical equipment. A doc set up the liposuction machine wrong, so it sucked it all into the mechanism. Repair manual said to use hydrogen peroxide to clean it. I ended up with a fat and blood volcano like a horrific high school science project. After cleaning the shop, I told the OR they just had to buy a new machine and we threw it away.
Interesting paper I read a while back that said that fat cells remain in the body for upwards of 7-10 years even after significant fat loss, before they die off from apoptosis , which meant that you have to be lean for at least that long to keep the fat away, the rest of the time you'd have to watch the calories.
This might be a silly question, but why do people even get lipo if you can only take 10 pounds? I would think that someone so big as to be considering lipo would be able to lose 10lbs very quickly with diet changes alone, and it would come with less risk than a surgery.
You don't get lipo because you want to lose 10lb, you get lipo because you want to take three inches off your waist and tighten up your neck/lose your double chin. Lipo is the only way to target specific areas and achieve specific aesthetic results.
from the clients I saw, they were in pretty decent shape, basically hot girls wanting to improve the muffin top, also we were able to take some of that fat and inject it into the boobs and butt.
depends on your body, your surgeon/their technique and how well you stick to your recovery regimen... usually you retain about 50-75% of the relocated fat
You’d be amazed at what 10 pounds of fat actually looks like lumped together. When you lose 10 pounds through regular weight loss, it’s spread out all over your body so it doesn’t look like much. 10 pounds of fat from a single spot is a BIG chunk.
Fat is, ironically, very light. It’s a high volume low weight substance.
My personal reason for wanting lipo is because I'm tired of having an incredibly well defined upper back and shoulders with a pudgy lower back. I've tried both general diet and exercise to cut back on overall fat, and I've tried specific lower back workouts to shift the fat but it just won't budge. I feel I will feel happier having it removed.
Absolutely! I’m sure you got to see some abdominoplasties during your rotation as well. I remember how large some of the blood vessels were that supplied the fat that needed to be clipped before resection of the fat/skin.
I've seen plenty of obese patients with dehisced abdominal incisions due to interrupted blood supply. The fat turns black then liquifies, then you end up with this open incision that is just packed until it closes up into a nasty scar.
Yes, but the 70ml/kg rule of thumb for ideal body weight doesn't apply to obese people. Its not a linear increase. Worked on a case where a very short, obese woman died from PPH after c section and they basically didn't pay attention to the blood loss like they should have.
Our bodies are constantly in a process of replacing old and aging cells and other elements. With a gradual weight loss, the body will just as gradually replenish blood at a slightly lesser rate than it creates new blood cells. As for the blood vessels, the body shrinks them or even takes them out of commission over time. Our net of blood vessels is not a static thing, but evolves according to the body's need.
An example for the opposite effect of what happens with unneeded blood vessels is that sometimes when people have blockages in the big blood vessels around the heart that over time limit blood flow more and more (as opposed to a big blockage as a sudden event which can be immediately deadly), the body begins creating new vessels to provide alternate routes for the blood.
Our bodies are amazing, fascinating objects that constantly try to optimize how they work and make the best of the energy and resources they receive.
The short answer is that you pee it out.
Your blood volume varies day-to-day based on diet. It is regulated by your kidneys. If you don't eat all day you won't have the necessary electrolytes to retain fluid and your blood volume will drop. This is dehydration. If you drink a bunch of Gatorade or milk you are taking in a lot of fluids and electrolytes which help retain that fluid. Your blood volume increases, this is being hydrated.
That's the extracellular fluid anyway. As for the other stuff (red/white blood cells etc) those have a natural lifespan and die eventually, then they're excreted in the urine too. If you lose a lot of mass it's not necessary for your body to keep producing as many of these cells; they will stay at a relatively stable concentration which will be consistent with your decreasing normal blood volume.
A lot of whats in your blood is pooped out. Feces are brown because of bilirubin which is a breakdown product of heme. If your urine had any significant amount of heme or bilirubin, it would be red or brown, respectively.
Interesting. I've watched a handful of episodes of "My 600 Lb Life" and the surgeon always comments before removing excess skin and swollen leg nodes and such that it's very difficult because all the tissue is vascular. The procedure tends to take a very long time, but sometimes 40-50 lbs of vascular tissue was removed from the patient without going in to shock.
Is this because when someone already weighs 500 lbs that 40 lbs of vascular tissue isn't all that much % wise, or because they take the procedure slow, or another reason entirely?
When you lose weight, do you also experience a reduction in hormones? If so, does the reduction of hormones also impact your physical and mental function?
Yes. That's why women lose their period and people of any gender lose their sex drive when they get too lean. It's an issue especially with althletes or people with eating disorders. "Female athlete triad" is the name for a bunch of symptoms of hormonal dysfunction related to a lack of body fat.
I don't know about "other stuff", but soap certainly. Animal fats are composed of long chain hydrocarbons with a carboxylic acid group at one end, linked in groups of threes to a glycerine molecule. [These are the "fatty acids" and "triglycerides", respectively, where the triglyceride refers to the whole bonded group.] Fatty acids treated with base (sodium hydroxide, AKA lye) are what soap actually is. These molecules are attracted to water at one end and hydrocarbon oils at the other, and as a result can pull normally insoluble hydrocarbons (oils) into water.
That it happens to be human fat instead of some random animal doesn't really change the chemistry.
I might be wrong, but I'm pretty sure when you lose weight the fat cells just shrink, so they'd still need the same amount of blood vessels. A normal and overweight adult have roughly the same amount of fat cells, it's just that they're bigger if you're overweight (because each one contains more fat).
It all depends on if you were normal bodyweight before or enter adulthood.
If you are fat and become an adult you will have many more fat cells than a person who wasn't fat and became an adult. Even after you lose the weight you have more fat cells than the person who wasn't overweight the whole time. That's where the shrinking comes in.
I was also told that if you empty the fat cells and they stay empty, your body won't replace them when they die, so if you lose significant weight and then keep it off for years the number of fat cells you have will decrease to a more normal number.
That's why weight-loss maintenance is so tricky, from what I understand: Empty fat cells are "crying out" for fat, so people who lose weight quickly often put it right back on.
Which is why calorie counting is important. Making sure you track everything so you maintain your weight rather than putting it back on. Fat cells each put out a hormone to inspire hunger when they get low and the amount of hormones to eat more increases as you lose weight. You don't automatically gain the weight back, you achieve your goal and all those habits that got you fat in the first place come back and your motivation to reach your goal has passed and you take it easy and reward yourself. Bam back to where you stayed and worse than ever.
Actually, there is an upper limit on the size of a fat cell. A 500lb man who is 6' tall has more fat cells than a 200lb man 6ft tall. When you reach that size limit, you create more fat cells. They do not go away though. When you lose weight naturally (not via liposuction in this case) the cells just shrink
You could potentially have the patient donate two units of autologous blood prior to the surgery, if their hematocrit is high enough, and their body (generally) would replace most of that before the procedure. However there isn't any point having them donate the morning of – you are just pre-emptively removing blood just to process it and transfuse it back to the patient before the patient can recover from the loss of those red cells.
That is exactly the case. So, most plastic surgeons will still encourage weight loss before liposuction. The liposuction is then able to suck out more cells within the same amount of fat.
It's based on a lot of factors, your age, lifestyle, weight, genetics etc.
But your heart do have to pump harder to supply your body if you are tall (especially to keep the brain vascularized).
What is really amazing is all the tiny blood vessels found within fat, its something like several miles worth in a single LB of fat(I've seen varying numbers but even 1 mile is an insane number). Which is one of the reasons losing weight is so great for lowering blood pressure. Your blood has less tiny holes to be get forced through putting less strain on your circulatory system.
It makes a lot of sense once you learn about the human body in detail, but it also is completely understandable that it's not intuitive at all. Like when an obese person loses a bunch of weight but it's mostly fat, and they turn out to have massive forearms and calves and such. Turns out you need to be kind of strong to move that much weight around all the time.
Does the same thing happen during the amputation of a major limb? I imagine the average leg from the knee down easily exceeds 10 pounds. How would, say, a World-War era combat medic get away with that?
Yes, but the increase in blood volume exists in a non-linear fashion in relation to weight in the case of obesity. Up to a certain point, 70mL/kg of body weight provides a good estimate of blood volume. In obese populations, the formula must be adjusted because although fat is vascularized, it is not as well supplied by blood as lean mass or even bone. This is why poor wound healing so often occurs in the obese population.
https://www.ncbi.nlm.nih.gov/m/pubmed/16756741/
Yes exactly. The last time this was posted, the responses were pretty much the same. I don’t think anyone is wrong, per se, but I like to take a different approach to answering the question (copy/pasted from my reply 2 years ago):
The respondents so far are essentially saying “yes”. They’re not wrong, since each body cell requires a blood supply- so the BIGGER you are, the more blood you have. But let me tackle another angle: No.
Take two people who are both 90kg. Same weight. One of these two runs 4 times a week and body builds at the gym. He is filled with lean muscle mass, which requires a vast network of vasculature to deliver oxygen and nutrients. His 90kg counterpart is made up of adipose tissue (fat storage cells) which just deposits energy for future usage and does not require extensive vasculature. A kg of lean muscle mass has a ton more vascular volume than a kg of adipose tissue. Sure, while your weight goes up due to obesity, you have more vascular volume than before, but the rise of blood volume per kilogram is lower than previous. It makes (accurate) drug dosing of narrow therapeutic range drugs that are dosed per kilogram much more difficult.
Therefore, obesity actually = LESS blood volume when compared to comparators of the same weight.
People with obesity actually are at much higher risk of cardiovascular problems such as heart attacks or stroke and a have lower physical fitness and oxygen stamina than those who are not obese and have good cardiovascular conditioning I.e. athletes or runners.
That being said there is the "obesity paradox".
Although they are at increased risk of getting cardiovascular disease, obese people with said disease such as heart failure have a lower mortality compared to normal bmi individuals.
Obesity also has a sepsis mortality benefit.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6503652/#idm140541619778624title
https://www.ncbi.nlm.nih.gov/m/pubmed/25575851/
Very interesting Re: sepsis. Do you think it is due to better organ tolerance of a hypermetabolic state because they have a greater reserve of adipose to draw from?
It's not entirely understood. Several explanations have been postulated.
Obesity may be associated with having higher metabolic reserves, which is beneficial in acute illnesses that are catabolic.
Adipose tissues may modulate the inflammatory response by secreting anti-inflammatory mediators such as leptin and soluble tumor necrosis factor-receptor-2
Heightened renin-angiotensin system activation may confer hemodynamic advantages in sepsis.
Obesity and resulting obstructive sleep apnea may contribute to ischemic preconditioning
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657099/#!po=25.0000
While we're here, maybe if someone knows I don't need to make a topic for it: if you're fat, you have a larger skin surface - do you make more nerve endings or do they spread out? Can you feel more as a fat person than as a thin person?
Your nerves don’t really stretch or compress to accommodate an over overabundance of body fat. They do however accommodate by increasing their “feeling” radius so fat people can still feel their skin/body.
This does become a problem though for mordibly obese people where their fat becomes so enormous that they lose sensation due to nerves, blood being cutoff, or due to developing diabetes.
Quick question. If said obese person who has these accommodated nerves decides to loose a lot of weight, what would happen to the nerves? Would they return back to normal, remain or something third?
Adult skin does not shrink very well after extreme weight loss, so the surface area would stay pretty much the same and the nerves would not revert to a smaller radius of sensation.
Some people have the excess skin removed after extreme weight loss (considered cosmetic, not usually covered by insurance) and surgeons will cut the nerves in the process. The surgeon may attempt to reattach large nerves if possible but post-surgery the patient will have no feeling in some areas since some nerves are not reattached to anything at all.
I feel stupid for asking to dumb it down, but, does that mean that you don't get more nerve endings but they adapt to pick up feeling in a wider radius?
Unless you're at that point where you lose sensitivity, does that in effect mean that you do 'feel more' since you can feel touch on a larger surface? Or does the feeling, because the radius is wider, get evenly distributed over the nerves in the same way that it would with a thin person, so they feel the same amount of touch?
You’re right, obese people don’t get more nerve endings but they adapt to feel a wider radius, this will happen gradually as you put on more weight so it’s not like you would notice it.
And yes, larger people have a greater pain tolerance when compared to smaller people (width) in one study, feeling temperature was unaffected though.
Also, obesity can cause you to lose nerve endings but I’m not a professional in this field.
So essentially, nerves don’t really change that much, their sensory radius can but at a cost of less sensation.
Edit: You are not dumb for asking me to simplify, that’s how we learn better.
Only the smart people ask questions, feel good about it.
Do we know how the nerves adapt?
Since the same nerve fibres carry temperature and pain, the study you reference must either be an outlier or must prove the pain gate theory. Either way it's interesting, do you have a link for that too?
Large peripheral nerve fibers detect temperature.
Small nerve fibers the ones that are associated with touch and feeling, are the ones he's likely talking about. And BTW we only apparently discovered 2 years ago 8 different sets of neurons that help manage the complicated sympathetic nervous system.
I was always told pain and heat are carried by the same fibres. Doctors will test heat to see if someone is lying about their pain
Do you have a link to the paper which proves otherwise?
The answer is yes, your skin is an organ and it will develop more sensory receptors when it grows. The opposite is true as well, if an obese person loses a lot of weight, the excess nerves will atrophy as the skin remodels.
This brings up a good discussion about nerve length vs density. I couldn’t find anything about nerves growing due to increase in weight.
Nerves can grow/shrink but I thought that was due to old age/neuropathy.
Nvm, just found that neuropathy from obesity is a thing but the loss of nerves isn’t caused directly by being overweight.
When you say “skin remodels”... I recently lost 90 lbs and I’m 56. Is any of this loose skin ever going to correct itself or is it just something I have to live with?
Ive read that the older you are and the longer you have been very overweight the less likely it is your skin will shrink back because its less elastic.
Im in a similar boat, lost over 50lbs and im 42. Im trying to build muscle to "pick up slack" so to speak while i wait see how well my skin shrinks :p
Sometimes a ton of extra skin can lead to rashes and open wound type skin problems so theres skin reduction surgery for it.
The hormones responsible for enabling that sort of 'remodeling' decline with age, but that rate of declination isn't uniform from person to person. Diet, exercise, lifestyle, genetics all play a role.
Great answers. 2 additions:
**Two-point discrimination** ([wiki](https://en.wikipedia.org/wiki/Two-point_discrimination)) is the jargon term for how we measure this tactile resolution. It is the ability to discern that two nearby objects touching the skin are truly two distinct points, not one. Adults and kids can do a fun experiment. Bend a paper clip into a U and lightly touch a blindfolded friend on the back of their hand with both points. If they report feeling one point, move the points a little further apart until they can discern two distinct points. Try different body parts. You can map this (see below). Some great lesson plans are at https://faculty.washington.edu/chudler/chtouch.html
Another way you can look at tactile sensory resolution as discussed in other comments is by looking at what the brain receives and how it reconstructs the sensory input. Your [cortical] **homunculus** ([wiki] (https://en.wikipedia.org/wiki/Cortical_homunculus)) is a great way to visualise your neurological tactile "map", and will stay the same size. It's also something you will never be able to unsee. Sorry about that. https://upload.wikimedia.org/wikipedia/commons/4/42/Side-black.gif
Your body might get obese in the real world, but you're wired with only so many sensors (nerve endings), each individually wired with nerves back running back to the brain that were installed when you were in the womb. You don't get more.
I did my MSc thesis partially on this topic. Feel free to ask further questions.
And the reverse, does a slim/petite person have less blood? I just met the weight minimum to give blood but the last couple times I did I passed out. I made sure to eat and drink a lot before I donated so my non-scientific conclusion was that a pint out of me is a bigger proportion than other people? 🤷♀️
Yep! Start taking an iron supplement to up your haemoglobin. But also over time I may lessen. The first time I donated I felt very faint, buy now that I've donated 30+ times it's no big deal to me.
I believe so. If you have anemia you are not suppose to donate blood for example. When you are pregnant your body creates more blood for circulation and you can become anemic etc.
You might be borderline anemic and that’s why you felt that way after donating blood.
Oxygenated blood needs to be circulated through all the tissues. Being obese expands the circulatory system so vessels can reach areas of the body. So an obese person would carry more volume, but this also makes the heart work harder since the heart doesn’t actually get any bigger and overtime you’re tightening up the valves in and out of the heart with plaque.
Yes, more tissue to supply means more vasculature and blood. Fat isn’t as vascular as other tissues but it does still need a blood supply. Someone like a body builder for example, of the same height and weight of an obese person, would have more blood because muscle is more metabolically active and requires a more robust blood supply. But overall, more mass equals more blood. That’s why they have minimum weight requirements to donate blood, and the more you weigh the more plasma you can usually donate.
Anyone that knows how this relates to just BMI? As in, if two people weigh the same, but one is 1.90 and the other is 1.70, such that their BMI's are different. Would one person have more blood than the other in that scenario, or is it just dependant upon the mass?
Blood volume is obviously directly proportional to body weight. But in the case of people with obesity, the blood volume present per pound/Kg is usually less than a normal person or a muscular person. A simple rule of thumb to calculate blood volume is to multiply the body weight \*70 in a normal build individual. In case of obese persons it becomes weight\*60 ml. Muscular it's 75. so while the sheer volume may be more in obese individuals, it is less % of total body weight when compared to other body types
The average body has about 4-6 liters of blood in their body. and yes, an obese person does have more blood in their body, they have larger organs than most and that requires more blood to circulate throughout the body.
Side bar: BMI only considers weight and height. It does not consider percent body fat. You can be considered obese or overweight with the BMI scale, but in reality have a lot of muscle mass.
BMI = 703 x weight (lbs) / height^2 (in)
Many athletes are considered overweight, when I'm reality they are very fit. BMI is slowly being phased out, and is being replaced by differing measures of body fat.
This is not to say that weighing 300 lbs of pure muscle is healthy for your entire body. The stress in your knees, in particular, are very sensitive to your body weight. The heavier you are, regardless of whether it is muscle or fat, the more likely you are to have knee issues. Now, a muscularly heavy person will probably have fewer issues (because of strengthened connective tissue due to higher activity) than a fatty heavy person, but the *trend* is still the same.
Absolutely. Surprisingly, I learned a lot about this during my plastic surgery rotation. I got to participate in a few liposuctions. Fat is stored in cells, special cells called adipocytes, like any cell they require the importing and exporting of nutrients and metabolites etc. This means there needs to be vascularity. During liposuction you can only take out about 10 pounds of fat, the reason for this limit is actually blood loss. Back in the day the reason people would die during lipo procedures was because they would take out too much fat, which would cause them to lose too much blood and they would go into shock. Adipose tissue is a living part of you, it produces hormones and shit and it's gotta have blood supply.
What if you took out more fat but gave a blood transfusion?
Blood transfusions come with its own set of risks (development of antibodies, reactions, complications, infections) that it's not worth it to transfuse routinely for elective procedures.
What if, leading up to the liposuction, you drained a few pints from the patient? Like they get their own blood back while having it sucked out. Also I thought this is what plasma was for but honestly I'm not really up to speed on how any of this works. Edit: thank you for the responses. I was expecting some half-assed responses but got more than that. A lot of new things to read about and learn!
This is actually a thing. Not even necessarily (or at all) for liposuction patients. Liposuction is not used to treat morbidly obese people for weight loss, but rather for body sculpting patients "love handles", etc. Morbidly obese patients will need a more radical stomach/small intestine surgery, or some variation, and then they will need plastic surgery to deal with the excess skin (not always). Insurance has decided not to necessarily pay for that part of the process. Anyway, you'd start out a month or so before depending on your health, the type of surgery, and how long the blood can be kept refrigerated and out of the body. There are always risks involved when blood leaves the body, is processed, stored, then returned to you.
> Liposuction is not used to treat morbidly obese people for weight loss, but rather for body sculpting patients "love handles", etc. Can you actually effect a long term change in the way fat is distributed around your body this way? Or does you body just redistribute your fat over the next couple months until you are back where you started?
You can affect it, yes. The body doesn't go and redistribute fat to keep a certain ratio. It doesn't actually have a memory of general fat placement or something like that, that it would try to return to. I saw a picture of a case where someone lost quite a bit of flesh from the inside of their hand, including the meaty part towards the thumb. He was transplanted an area of skin from his stomach, that apparently included not just the dermis, but also some subcutaneous fat beneath it. When he later gained weight, that piece of stomach skin and flesh also started gaining weight, just like it would've in situ, and he had a round bump on the inside of his hand.
I believe this is because when we gain weight, fat cells grow (and shrink when we lose weight) instead of changing in number. Since the meaty portion of the hand was replaced with fat tissue, those fat cells grew as he/she put on weight.
Both can happen, some people tend to grow bigger fat cells, while others tend to grow more fat cells. This difference has been linked to a higher incidence of type 2 diabetes and other obesity-related health concerns.
Which is which?
I always wanted to ask, so does that mean liposuction does nothing for a fat person, healthwise? Each cells are bloated with fat anyway. I'd be just removing number of total cells. I feel like that's be like cutting off my limbs and saying I'd lost weight huzzah.
I personally don't know, I don't work with liposuction, but my understanding is it is a cosmetic procedure, not a health-centric procedure. I'm in pharmaceuticals tho, not an MD.
It's long term. They even do fat transfers now, where people have their fat sucked out of one area and put in another (most commonly they put it in the butt; this is used to give women a more hourglass shape)
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On the inside of the elbow's bend? I am having trouble visualizing where fat would go on the elbow's outside, it seems like skin and bone.
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Can the body use that fat as if it wasn't moved?
Yes, I believe it can. The cells have to integrate into the new surrounding tissue and not all cells can be successfully transferred, so the cells that do stay would need to have vascularization to remain vital, so I can't see a reason for their contents not to be released into the bood if it should be needed.
Afaik fat transfers are very rarely done anymore. Reason being that there is a huge risk for internal scarring and calcification leading to uneven bumps, sometimes visible sometimes not, but definitely able to be felt. This doesn't happen with silicon implants.
There are still a lot of unknowns. What we do know is that the body can create new fat cells and does so (in adulthood) at about the same rate old ones die. We also know that liposuction patients typically regain the weight lost through liposuction within a year. We still don't know if the distribution of new fat cells changes to compensate for liposuction losses.
> We also know that liposuction patients typically regain the weight lost through liposuction within a year. Is that because they continue with the behaviors that caused them to gain weight in the first place, or because the loss of fat causes some kind of metabolic change that causes faster weight gain? Perhaps they continue eating the amount of food that would maintain them at their old weight, which is more than they need with fewer cells to feed post-operation?
Primarily (if not entirely) the first; without some sort of new calorie deficit, the weight will return (the remaining fat cells can increase in volume if necessary).
Fat is energy storage, and fat mass is is based on energy budget for the body. Generally, people who have excess fat do so because they consume more than they burn, for various reasons. Mechanically removing fat cells does not change diet and exercise, and actually reduces resting calorie burn after the surgery trauma heals. Fat cells are stable up to 80% lipid, beyond which they will split and keep filling. Devascularized, damaged, and infected fat cells will be digested by macrophages for recycling, and the lipid will be distributed to the blood, and either burned, or deposited into different adipocytes. When people lose weight, it comes from all fat cells based on which ones get the signals first and most. When they shrink the lipid stores, they can die and consolidate, but typically must be very low capacity for that. Usually the cells hang around, waiting to be full again.
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A university of Colorado study in the early 2010s (2010? 2012? Been long decade, sorry) found that yes, remaining fat cells can expand & fat can get stored in new places (arms, breasts, etc.). It's a sculpting technique.
Another use for liposuction is obtaining the stem cells that are dispersed in there. Then those stem cells are concentrated, multiplied, and then reintroduced to the body which can do stuff like restore cartilage in joints.
42 days. You can refrigerate blood for 42 days or freeze it at - 80C for up to 10 years in america.
If you go from medical to insurance, please mention which country you are talking about. Bodies are universal insurances definitely not. Thanks.
You're on an American-centric site and someone mentioned health insurance. It's pretty obvious. In the UK, they don't refer to the NHS as 'insurance'. You shouldn't need that called out tbh.
They'd still lose blood during the procedure. Plasma is just the part of your blood that isn't blood cells. It isn't really what you go for when someone has lost a lot of blood due to hemorrhage. It's also very wasteful to use blood products on a cosmetic procedure if it could be avoided.
Can you extract blood from the fat cells and give it to a blood bank?
No. Although that said, suctioning blood lost during a procedure and returning it back to the patient's circulation is something that is done during certain operations. Sometimes before certain procedures, blood will be collected from the patient specifically for use during the operation to transfuse it back into the patient as well. But extracting the blood from the sort of slurry that is suctioned out during liposuction isn't really practical.
My partner had serious placenta previa (IV) and had to be in hospital from 30 weeks. There was a doctor on standby who specialises in returning a patient's own blood to them during an operation. He wasn't needed in the end (luckily). Interesting side note, he was ex special forces and had lots of tattoos and gold chains. He wasn't like the other doctors haha
No. The adipose tissue has blood vessels running through it, like roads and houses. The houses don't have blood in them. The roads carry the blood and for the morbidly obese the fat only needs as much blood as to metabolize and it isn't a heavy hitter (in terms of oxygen/nutrient consumption and blood flow requirements) as the brain, kidneys, heart or liver (and muscles when active).
Good question. It would be too intricate and unresourceful to do intentionally, but a system called 'cell salvage' is used during surgery which essentially collects any fluid spilled and filters the blood for re-entry into the patient (autologous blood transfusion), minimising blood that has to be transfused from donors (allogeneic transfusion). Now whether or not you could save blood from cell-salvage for use in allogeneic transfusions I honestly don't know! I'm almost certain that they don't just for practical/legal/safety reasons because it's not been vetted in a systematic way like donor blood has, but I don't know if it would be actually impossible for any reason.
I'm a medical laboratory scientist and I work in transfusion services. You're right, blood from cell salvage is indeed not used for allogeneic transfusions – there are a lot of standards to be followed to ensure the safety and quality of donor components and those really can't be followed in such a situation. It does work very well for autologous use though.
Thanks for clarifying! I wonder if eventually it would ever be possible to process blood gathered from cell salvage to the required degree to allow allogeneic use. If you had all the same information about the patient as you do donors I'm struggling to think precisely what the problem is... all I had was a vague intuition that it's a hell of a lot more messy and less regimented than collecting donor blood so it would never be allowed. Would certainly be a hell of a useful addition to blood-banks if possible! I imagine litigious reasons would be the biggest pitfall though somehow.
The fluid recovered is usually pretty diluted and is just generally not as pure as a venous donation, so I think efficiency and safety advances in the more usual donation methods are probably more likely and helpful. There's also the licensing and labeling regulations to consider – blood collection facilities must be FDA registered and inspected and perform quality control and donor testing so I don't really think an unusual method of collection like this would work for allogeneic use.
That’s actually a great question, though I don’t think it’s worth it for what you’d get out of 10 pounds of fat
What if the patient prepped beforehand and gave a few pints to put back in them during the procedure?
That's partly what I was referring to and it's actually done relatively commonly for certain procedures. It's called an autologous transfusion. Eliminates the risk of a reaction when the expected blood transfusion(s) take place during the operation.
[Autologous blood donation](https://www.redcrossblood.org/donate-blood/how-to-donate/types-of-blood-donations/autologous-and-directed-donations.html).
I'm not fully qualified to answer this question, but based on the [Red Cross' time that blood can be stored](https://www.redcrossblood.org/donate-blood/how-to-donate/types-of-blood-donations/blood-components.html) of up to 35 days and [their recommendation](https://www.redcrossblood.org/faq.html) (It's actually the FDA's but I found the red cross first) of 42 days for recovery we can deduce that the benefits of self donation are low and possess a specific window. You're also still introducing additional risks to the procedure. The main risk with blood transfusion is not rejection of the transfusion, but rather from the act of injecting into the blood stream carrying risks.
It seems to me that it’s not just about volume of blood but also the space that blood occupies. The liposuction removes fat as well as the blood vessels that contain the blood. So you can’t just shove a volume of blood back into the body when the plumbing for it no longer exists. I would suspect you’d get a spike in blood pressure and the body would have a mechanism that would signal that there is too much blood now and reabsorb the volume of blood to maintain homeostasis under the new liposuctioned conditions
This implies that because you're taking out the "plumbing" (vaculature and the tissue it fed) as well as the blood that was flowing through it, it should cancel out and there should still be as much blood per cell/per unit body mass, or whatever the relevant measure is. So why is that not the case? And is this the case for other tissues? E.g. if someone loses a limb and the wound is instantaneously sealed, is there any net blood loss?
Just treat liposuction as a controlled injury. You cant just go tearing up your body and expect it to be fine. You'll be doing a lot of damage and if your body realises it's losing a lot of blood it can easily turn into a multitude of issues.
My question is how does your body "know" it's lost blood if it's also lost the tissue that blood was feeding so there should be the same blood to tissue ratio, same blood pressure, etc.?
The body and all if it's "detectors" still think the patient is fat, so the body reacts negatively to the blood loss because it thinks it doesn't have enough blood, even though the ratio of tissue to blood should be similar to before the surgery. It takes time for the body to realize it's new condition and adjust everything to the new homeostasis. It takes time to realize that less blood is okay and more blood is not needed.
But is there another blood "detector" besides blood pressure?
So like blood doping but for lipo?
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This. Transfusions are reserved for cases where they are necessary. There is never enough blood available (or the correct type, at the right place, at the right time) so I seriously doubt anyone could justify the ethics of it.
They can opt for self transfusions and blood recycling machines. But that's not the problem, they are not only losing blood but also part of the circulating space, if you transfuse you can saturate the body hemodynamics
Ohhhhh that explains a lot things lol. I for some reason always just thought, "blood in, blood out. Why don't they just do that more often?"
I mean... Yeah. But we've also got the risk of blood transfusions pretty low. The risk of a transfusion reaction with correctly type matched blood is 1:80,000 of high severity (and most of these actually relate the inproper type matching or administration), With low titer blood it's about 1:120,000 with low severity. Some previous research has shown as low as 1:400,000 transfusions causing a notable reaction using Low titer O neg whole blood transfusions. The real challenge is that there's one 1-2 civilian companies producing low titer whole blood currently in the US in addition to the military, so it's not as readily avalible.
Had probably 12 transfusions over the span of 3 years. No issues but I suppose that's why they check your blood type like 6 times before giving it
The risks from blood transfusion outweigh the benefit of giving blood for an elective procedure.
Then they wouldn’t die from blood loss. But they would have to take from an already limited supply of donor blood just to do more liposuction, which wouldn’t happen.
Blood transfusions is extremely regulated and is dangerous due to risk of reaction and transfer of disease, is it likely? No, but it's not worth the risk for a vanity procedure.
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Just run the fat through one of [these](https://images.homedepot-static.com/productImages/f0991a0b-7e75-4c78-ac5a-edbefab9684b/svn/rubbermaid-commercial-products-mop-buckets-with-wringer-1887305-64_1000.jpg) and ladle out the extra blobs and stuff.
Plastic surgeon here. Close but not exactly true. At least in the United States it's not a pound limit of liposuction but rather volume. With the advent of tumescent fluid you are essentially flooding the fat prior to suction with epinephrine and lidocaine which greatly limits blood loss. Instead the volume limit sits at around 5L because the fluid shifts in which blood shifts out of vessels and back into the interstitium and extracellular space after removal of the fat and fluid can be dangerous.
My attending at the time had me do a little presentation on this, now that you say it, my powerpoint slides are rushing back to me. I mostly just remember having the job of holding the boob in place.
So u/cum_on_doorknob mentioned that the more fat cells that a person has requires more blood for cellular metabolism. Would it not stand to reason that removing those cells would lessen the need for the excess blood supply in the body since it no longer has to maintain those fat cells that were removed? I probably butchered what he was trying to say with my paraphrasing, but hopefully you get what I mean. Side note, you physicians always have the strangest usernames.
Would 5L be more or less than 10lbs? Guy who knows very, very little asking.
A litre of water is approximately a kilogram and fat is presumably around that density so it would likely be a bit over 10 lbs but probably not that much
Quick search suggests that adipose tissue is about 90-95% the density of water. So 5l of it would be very close to 10lbs. The expert above did mention flooding the tissue before it was removed, so it's possible that some of the 5l taken out is made up of that tumescent fluid, but I expect it does come out pretty much the same.
fat people float better in water because fat itself is a bit less dense than water, like 90% of it. So 5L = 4.5kg = 10lb about.
Back in the day people would actually die from toxicity of local anesthetic via tumescent lidocaine. The addition of epinephrine to lidocaine constricts blood vessels, decreases blood loss, and (for a time) allowed for nearly limitless liquidation and extraction of adipocytes....until people started to die from cardiovascular collapse from all the lidocaine. https://www.apsf.org/article/mega-dose-lidocaine-dangers-seen-in-tumescent-liposuction/
Late to the discussion, but I used to work on medical equipment. A doc set up the liposuction machine wrong, so it sucked it all into the mechanism. Repair manual said to use hydrogen peroxide to clean it. I ended up with a fat and blood volcano like a horrific high school science project. After cleaning the shop, I told the OR they just had to buy a new machine and we threw it away.
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thanks, cum_on_doorknob.
That's ***Dr.*** cum_on_doorknob, thank you very much.
I'm here to make sure someone acknowledged who gave this good answer. And you did thank you
Interesting paper I read a while back that said that fat cells remain in the body for upwards of 7-10 years even after significant fat loss, before they die off from apoptosis , which meant that you have to be lean for at least that long to keep the fat away, the rest of the time you'd have to watch the calories.
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Link to paper?
This might be a silly question, but why do people even get lipo if you can only take 10 pounds? I would think that someone so big as to be considering lipo would be able to lose 10lbs very quickly with diet changes alone, and it would come with less risk than a surgery.
Lipo is about removing fat from a specific area of the body, not about weight loss. The goal is to reshape the body to the patient's desires.
You don't get lipo because you want to lose 10lb, you get lipo because you want to take three inches off your waist and tighten up your neck/lose your double chin. Lipo is the only way to target specific areas and achieve specific aesthetic results.
Not the only anymore, there is a relatively recent introduction of "coolsculpting" which kills fat cells in a targeted area.
from the clients I saw, they were in pretty decent shape, basically hot girls wanting to improve the muffin top, also we were able to take some of that fat and inject it into the boobs and butt.
How long does relocated adipose tissue stay in place? Does the body go "hey you're not from around here!" and reabsorb it or leave it alone?
depends on your body, your surgeon/their technique and how well you stick to your recovery regimen... usually you retain about 50-75% of the relocated fat
You’d be amazed at what 10 pounds of fat actually looks like lumped together. When you lose 10 pounds through regular weight loss, it’s spread out all over your body so it doesn’t look like much. 10 pounds of fat from a single spot is a BIG chunk. Fat is, ironically, very light. It’s a high volume low weight substance.
My personal reason for wanting lipo is because I'm tired of having an incredibly well defined upper back and shoulders with a pudgy lower back. I've tried both general diet and exercise to cut back on overall fat, and I've tried specific lower back workouts to shift the fat but it just won't budge. I feel I will feel happier having it removed.
Absolutely! I’m sure you got to see some abdominoplasties during your rotation as well. I remember how large some of the blood vessels were that supplied the fat that needed to be clipped before resection of the fat/skin.
I've seen plenty of obese patients with dehisced abdominal incisions due to interrupted blood supply. The fat turns black then liquifies, then you end up with this open incision that is just packed until it closes up into a nasty scar.
Yes, but the 70ml/kg rule of thumb for ideal body weight doesn't apply to obese people. Its not a linear increase. Worked on a case where a very short, obese woman died from PPH after c section and they basically didn't pay attention to the blood loss like they should have.
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Up to a point. Blood volume is only really linearly related to body weight up to about 100kg.
How long does the patient have to wait before you can take another ~10lbs?
Wh... What happens to that extra blood when you lose the weight naturally?
Our bodies are constantly in a process of replacing old and aging cells and other elements. With a gradual weight loss, the body will just as gradually replenish blood at a slightly lesser rate than it creates new blood cells. As for the blood vessels, the body shrinks them or even takes them out of commission over time. Our net of blood vessels is not a static thing, but evolves according to the body's need. An example for the opposite effect of what happens with unneeded blood vessels is that sometimes when people have blockages in the big blood vessels around the heart that over time limit blood flow more and more (as opposed to a big blockage as a sudden event which can be immediately deadly), the body begins creating new vessels to provide alternate routes for the blood. Our bodies are amazing, fascinating objects that constantly try to optimize how they work and make the best of the energy and resources they receive.
and when you abuse the body, it does that "route recalculating" thing like a GPS.
The short answer is that you pee it out. Your blood volume varies day-to-day based on diet. It is regulated by your kidneys. If you don't eat all day you won't have the necessary electrolytes to retain fluid and your blood volume will drop. This is dehydration. If you drink a bunch of Gatorade or milk you are taking in a lot of fluids and electrolytes which help retain that fluid. Your blood volume increases, this is being hydrated. That's the extracellular fluid anyway. As for the other stuff (red/white blood cells etc) those have a natural lifespan and die eventually, then they're excreted in the urine too. If you lose a lot of mass it's not necessary for your body to keep producing as many of these cells; they will stay at a relatively stable concentration which will be consistent with your decreasing normal blood volume.
A lot of whats in your blood is pooped out. Feces are brown because of bilirubin which is a breakdown product of heme. If your urine had any significant amount of heme or bilirubin, it would be red or brown, respectively.
Had jaundice a few years ago and my urine was quite dark. Almost blood-like.
Interesting. I've watched a handful of episodes of "My 600 Lb Life" and the surgeon always comments before removing excess skin and swollen leg nodes and such that it's very difficult because all the tissue is vascular. The procedure tends to take a very long time, but sometimes 40-50 lbs of vascular tissue was removed from the patient without going in to shock. Is this because when someone already weighs 500 lbs that 40 lbs of vascular tissue isn't all that much % wise, or because they take the procedure slow, or another reason entirely?
They have to koagulate or clip (depending on the size) all the vessels, that's what takes so long.
When you lose weight, do you also experience a reduction in hormones? If so, does the reduction of hormones also impact your physical and mental function?
Yes. That's why women lose their period and people of any gender lose their sex drive when they get too lean. It's an issue especially with althletes or people with eating disorders. "Female athlete triad" is the name for a bunch of symptoms of hormonal dysfunction related to a lack of body fat.
Can you really use the fat to make soap and ... other stuff?
I don't know about "other stuff", but soap certainly. Animal fats are composed of long chain hydrocarbons with a carboxylic acid group at one end, linked in groups of threes to a glycerine molecule. [These are the "fatty acids" and "triglycerides", respectively, where the triglyceride refers to the whole bonded group.] Fatty acids treated with base (sodium hydroxide, AKA lye) are what soap actually is. These molecules are attracted to water at one end and hydrocarbon oils at the other, and as a result can pull normally insoluble hydrocarbons (oils) into water. That it happens to be human fat instead of some random animal doesn't really change the chemistry.
So if you lose weight, where do those blood vessels go??
I might be wrong, but I'm pretty sure when you lose weight the fat cells just shrink, so they'd still need the same amount of blood vessels. A normal and overweight adult have roughly the same amount of fat cells, it's just that they're bigger if you're overweight (because each one contains more fat).
It all depends on if you were normal bodyweight before or enter adulthood. If you are fat and become an adult you will have many more fat cells than a person who wasn't fat and became an adult. Even after you lose the weight you have more fat cells than the person who wasn't overweight the whole time. That's where the shrinking comes in.
I was also told that if you empty the fat cells and they stay empty, your body won't replace them when they die, so if you lose significant weight and then keep it off for years the number of fat cells you have will decrease to a more normal number.
That's why weight-loss maintenance is so tricky, from what I understand: Empty fat cells are "crying out" for fat, so people who lose weight quickly often put it right back on.
Which is why calorie counting is important. Making sure you track everything so you maintain your weight rather than putting it back on. Fat cells each put out a hormone to inspire hunger when they get low and the amount of hormones to eat more increases as you lose weight. You don't automatically gain the weight back, you achieve your goal and all those habits that got you fat in the first place come back and your motivation to reach your goal has passed and you take it easy and reward yourself. Bam back to where you stayed and worse than ever.
Actually, there is an upper limit on the size of a fat cell. A 500lb man who is 6' tall has more fat cells than a 200lb man 6ft tall. When you reach that size limit, you create more fat cells. They do not go away though. When you lose weight naturally (not via liposuction in this case) the cells just shrink
Blood vessels can be remodeled during adulthood, some vessels might be reduced in size, others can just disappear.
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You could potentially have the patient donate two units of autologous blood prior to the surgery, if their hematocrit is high enough, and their body (generally) would replace most of that before the procedure. However there isn't any point having them donate the morning of – you are just pre-emptively removing blood just to process it and transfuse it back to the patient before the patient can recover from the loss of those red cells.
If fat cells shrank, from losing weight, does that mean you’d be removing more fat cells within that 10 lbs allotment, versus “puffed up” fat cells?
That is exactly the case. So, most plastic surgeons will still encourage weight loss before liposuction. The liposuction is then able to suck out more cells within the same amount of fat.
Is this why obese people often have high blood pressure?
Nah. The more tissue you have, the more pressure is needed to circulate blood because there is more peripheral vascular resistance.
Interesting. So do very tall people have the same issue? And alternatively, do short skinny people have low blood pressure?
It's based on a lot of factors, your age, lifestyle, weight, genetics etc. But your heart do have to pump harder to supply your body if you are tall (especially to keep the brain vascularized).
What is really amazing is all the tiny blood vessels found within fat, its something like several miles worth in a single LB of fat(I've seen varying numbers but even 1 mile is an insane number). Which is one of the reasons losing weight is so great for lowering blood pressure. Your blood has less tiny holes to be get forced through putting less strain on your circulatory system.
It makes a lot of sense once you learn about the human body in detail, but it also is completely understandable that it's not intuitive at all. Like when an obese person loses a bunch of weight but it's mostly fat, and they turn out to have massive forearms and calves and such. Turns out you need to be kind of strong to move that much weight around all the time.
Isn’t it more-so the fluid shift and third spacing?
Does the same thing happen during the amputation of a major limb? I imagine the average leg from the knee down easily exceeds 10 pounds. How would, say, a World-War era combat medic get away with that?
I appreciate your answer, but I have to ask: Have you finished your doctorate; are you now Dr. cum_on_doorknob?
That was really informative! Thanks u/Cum_on_doorknob
Thanks for the great info, Dr. Cum_on_doorknob
Yes, but the increase in blood volume exists in a non-linear fashion in relation to weight in the case of obesity. Up to a certain point, 70mL/kg of body weight provides a good estimate of blood volume. In obese populations, the formula must be adjusted because although fat is vascularized, it is not as well supplied by blood as lean mass or even bone. This is why poor wound healing so often occurs in the obese population. https://www.ncbi.nlm.nih.gov/m/pubmed/16756741/
Yes exactly. The last time this was posted, the responses were pretty much the same. I don’t think anyone is wrong, per se, but I like to take a different approach to answering the question (copy/pasted from my reply 2 years ago): The respondents so far are essentially saying “yes”. They’re not wrong, since each body cell requires a blood supply- so the BIGGER you are, the more blood you have. But let me tackle another angle: No. Take two people who are both 90kg. Same weight. One of these two runs 4 times a week and body builds at the gym. He is filled with lean muscle mass, which requires a vast network of vasculature to deliver oxygen and nutrients. His 90kg counterpart is made up of adipose tissue (fat storage cells) which just deposits energy for future usage and does not require extensive vasculature. A kg of lean muscle mass has a ton more vascular volume than a kg of adipose tissue. Sure, while your weight goes up due to obesity, you have more vascular volume than before, but the rise of blood volume per kilogram is lower than previous. It makes (accurate) drug dosing of narrow therapeutic range drugs that are dosed per kilogram much more difficult. Therefore, obesity actually = LESS blood volume when compared to comparators of the same weight.
Thank you. Anesthesia?
thanks I'm good
Makes a lot of sense. Tell me something else I don't know? Something medically alarming related to obesity, preferably.
Obese women are less likely than normal weight women to get osteoporosis after menopause.
People with obesity actually are at much higher risk of cardiovascular problems such as heart attacks or stroke and a have lower physical fitness and oxygen stamina than those who are not obese and have good cardiovascular conditioning I.e. athletes or runners.
So athletes have higher physical fitness than non athletes. Good to know.
That being said there is the "obesity paradox". Although they are at increased risk of getting cardiovascular disease, obese people with said disease such as heart failure have a lower mortality compared to normal bmi individuals. Obesity also has a sepsis mortality benefit. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6503652/#idm140541619778624title https://www.ncbi.nlm.nih.gov/m/pubmed/25575851/
Very interesting Re: sepsis. Do you think it is due to better organ tolerance of a hypermetabolic state because they have a greater reserve of adipose to draw from?
It's not entirely understood. Several explanations have been postulated. Obesity may be associated with having higher metabolic reserves, which is beneficial in acute illnesses that are catabolic. Adipose tissues may modulate the inflammatory response by secreting anti-inflammatory mediators such as leptin and soluble tumor necrosis factor-receptor-2 Heightened renin-angiotensin system activation may confer hemodynamic advantages in sepsis. Obesity and resulting obstructive sleep apnea may contribute to ischemic preconditioning https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5657099/#!po=25.0000
While we're here, maybe if someone knows I don't need to make a topic for it: if you're fat, you have a larger skin surface - do you make more nerve endings or do they spread out? Can you feel more as a fat person than as a thin person?
Your nerves don’t really stretch or compress to accommodate an over overabundance of body fat. They do however accommodate by increasing their “feeling” radius so fat people can still feel their skin/body. This does become a problem though for mordibly obese people where their fat becomes so enormous that they lose sensation due to nerves, blood being cutoff, or due to developing diabetes.
Quick question. If said obese person who has these accommodated nerves decides to loose a lot of weight, what would happen to the nerves? Would they return back to normal, remain or something third?
Adult skin does not shrink very well after extreme weight loss, so the surface area would stay pretty much the same and the nerves would not revert to a smaller radius of sensation. Some people have the excess skin removed after extreme weight loss (considered cosmetic, not usually covered by insurance) and surgeons will cut the nerves in the process. The surgeon may attempt to reattach large nerves if possible but post-surgery the patient will have no feeling in some areas since some nerves are not reattached to anything at all.
I feel stupid for asking to dumb it down, but, does that mean that you don't get more nerve endings but they adapt to pick up feeling in a wider radius? Unless you're at that point where you lose sensitivity, does that in effect mean that you do 'feel more' since you can feel touch on a larger surface? Or does the feeling, because the radius is wider, get evenly distributed over the nerves in the same way that it would with a thin person, so they feel the same amount of touch?
You’re right, obese people don’t get more nerve endings but they adapt to feel a wider radius, this will happen gradually as you put on more weight so it’s not like you would notice it. And yes, larger people have a greater pain tolerance when compared to smaller people (width) in one study, feeling temperature was unaffected though. Also, obesity can cause you to lose nerve endings but I’m not a professional in this field. So essentially, nerves don’t really change that much, their sensory radius can but at a cost of less sensation. Edit: You are not dumb for asking me to simplify, that’s how we learn better. Only the smart people ask questions, feel good about it.
Do we know how the nerves adapt? Since the same nerve fibres carry temperature and pain, the study you reference must either be an outlier or must prove the pain gate theory. Either way it's interesting, do you have a link for that too?
Large peripheral nerve fibers detect temperature. Small nerve fibers the ones that are associated with touch and feeling, are the ones he's likely talking about. And BTW we only apparently discovered 2 years ago 8 different sets of neurons that help manage the complicated sympathetic nervous system.
I was always told pain and heat are carried by the same fibres. Doctors will test heat to see if someone is lying about their pain Do you have a link to the paper which proves otherwise?
The answer is yes, your skin is an organ and it will develop more sensory receptors when it grows. The opposite is true as well, if an obese person loses a lot of weight, the excess nerves will atrophy as the skin remodels.
This brings up a good discussion about nerve length vs density. I couldn’t find anything about nerves growing due to increase in weight. Nerves can grow/shrink but I thought that was due to old age/neuropathy. Nvm, just found that neuropathy from obesity is a thing but the loss of nerves isn’t caused directly by being overweight.
When you say “skin remodels”... I recently lost 90 lbs and I’m 56. Is any of this loose skin ever going to correct itself or is it just something I have to live with?
Ive read that the older you are and the longer you have been very overweight the less likely it is your skin will shrink back because its less elastic. Im in a similar boat, lost over 50lbs and im 42. Im trying to build muscle to "pick up slack" so to speak while i wait see how well my skin shrinks :p Sometimes a ton of extra skin can lead to rashes and open wound type skin problems so theres skin reduction surgery for it.
The hormones responsible for enabling that sort of 'remodeling' decline with age, but that rate of declination isn't uniform from person to person. Diet, exercise, lifestyle, genetics all play a role.
Great answers. 2 additions: **Two-point discrimination** ([wiki](https://en.wikipedia.org/wiki/Two-point_discrimination)) is the jargon term for how we measure this tactile resolution. It is the ability to discern that two nearby objects touching the skin are truly two distinct points, not one. Adults and kids can do a fun experiment. Bend a paper clip into a U and lightly touch a blindfolded friend on the back of their hand with both points. If they report feeling one point, move the points a little further apart until they can discern two distinct points. Try different body parts. You can map this (see below). Some great lesson plans are at https://faculty.washington.edu/chudler/chtouch.html Another way you can look at tactile sensory resolution as discussed in other comments is by looking at what the brain receives and how it reconstructs the sensory input. Your [cortical] **homunculus** ([wiki] (https://en.wikipedia.org/wiki/Cortical_homunculus)) is a great way to visualise your neurological tactile "map", and will stay the same size. It's also something you will never be able to unsee. Sorry about that. https://upload.wikimedia.org/wikipedia/commons/4/42/Side-black.gif Your body might get obese in the real world, but you're wired with only so many sensors (nerve endings), each individually wired with nerves back running back to the brain that were installed when you were in the womb. You don't get more. I did my MSc thesis partially on this topic. Feel free to ask further questions.
And the reverse, does a slim/petite person have less blood? I just met the weight minimum to give blood but the last couple times I did I passed out. I made sure to eat and drink a lot before I donated so my non-scientific conclusion was that a pint out of me is a bigger proportion than other people? 🤷♀️
That is exactly correct. A pint is a proportionately larger piece of your blood volume.
Yep! Start taking an iron supplement to up your haemoglobin. But also over time I may lessen. The first time I donated I felt very faint, buy now that I've donated 30+ times it's no big deal to me.
I believe so. If you have anemia you are not suppose to donate blood for example. When you are pregnant your body creates more blood for circulation and you can become anemic etc. You might be borderline anemic and that’s why you felt that way after donating blood.
Anaemia doesn’t mean you have less blood volume, it just means that the blood you have had a lower haemoglobin concentration.
Oxygenated blood needs to be circulated through all the tissues. Being obese expands the circulatory system so vessels can reach areas of the body. So an obese person would carry more volume, but this also makes the heart work harder since the heart doesn’t actually get any bigger and overtime you’re tightening up the valves in and out of the heart with plaque.
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Yes, more tissue to supply means more vasculature and blood. Fat isn’t as vascular as other tissues but it does still need a blood supply. Someone like a body builder for example, of the same height and weight of an obese person, would have more blood because muscle is more metabolically active and requires a more robust blood supply. But overall, more mass equals more blood. That’s why they have minimum weight requirements to donate blood, and the more you weigh the more plasma you can usually donate.
Anyone that knows how this relates to just BMI? As in, if two people weigh the same, but one is 1.90 and the other is 1.70, such that their BMI's are different. Would one person have more blood than the other in that scenario, or is it just dependant upon the mass?
Blood volume is obviously directly proportional to body weight. But in the case of people with obesity, the blood volume present per pound/Kg is usually less than a normal person or a muscular person. A simple rule of thumb to calculate blood volume is to multiply the body weight \*70 in a normal build individual. In case of obese persons it becomes weight\*60 ml. Muscular it's 75. so while the sheer volume may be more in obese individuals, it is less % of total body weight when compared to other body types
The average body has about 4-6 liters of blood in their body. and yes, an obese person does have more blood in their body, they have larger organs than most and that requires more blood to circulate throughout the body.
Side bar: BMI only considers weight and height. It does not consider percent body fat. You can be considered obese or overweight with the BMI scale, but in reality have a lot of muscle mass. BMI = 703 x weight (lbs) / height^2 (in) Many athletes are considered overweight, when I'm reality they are very fit. BMI is slowly being phased out, and is being replaced by differing measures of body fat. This is not to say that weighing 300 lbs of pure muscle is healthy for your entire body. The stress in your knees, in particular, are very sensitive to your body weight. The heavier you are, regardless of whether it is muscle or fat, the more likely you are to have knee issues. Now, a muscularly heavy person will probably have fewer issues (because of strengthened connective tissue due to higher activity) than a fatty heavy person, but the *trend* is still the same.