True or Woo?
oolou
Posts: 765 Member
Losing weight very fast is not the same thins as losing fat. In order to lose fat, a reasonable deficit (which WILL seem to take more time) is a better solution. The body can only burn so much fat per day; after that any loss that you see will likely be muscle (after water weight). If you keep too steep of a deficit, you will lose muscle all over your body to include critical organs like your heart. If you keep it up for too long, you can do serious damage.
Just read this in a different thread and wondered if it's true (or woo). I read so many things here from different folk (all whom I know are trying to help and which I appreciate!) but sometimes I think ... hmm. Can the body only burn so much fat each day? And if so ... how much?
Thx!
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Yes it's true. I think the number is something like 31 calories per pound of weight. But that's also why those who weigh more can lose at higher rates.13
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Here is a non-woo explanation of fat loss but it does not address your question.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2376744/#!po=45.8333
I had to add google scholar to my search terms to find anything approaching sensible.1 -
I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.4
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nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
I agree, though this "fat loss limit per day" topic is new to me. It's an interesting topic and I'm totally willing to be wrong, though.
I mean... I can see how... say... working out for like 7 hours isn't going to burn more fat because you have muscle, water, etc. But at the same time, we look at *real* starvation situations and while there is virtually no muscle, there is equally low fat. But there are definitely organs left. It would seem more reasonable to think "there is a point where your body is burning more water and muscle than fat". But an actual fat loss limit??2 -
The 31 calorie thing is a theoretical limit based on a review of several studies. I've never seen an actual study built specifically to research it.
I get more concerned with people eating too little to support their basic nutrition needs. Eating too little protein encourages muscle loss. Too little fat causes hormone problems and vitamin malabsorption. Too few carbs can cause energy problems. Too few calories in general can cause serious hormone issues.8 -
WendyLeigh1119 wrote: »nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
I agree, though this "fat loss limit per day" topic is new to me. It's an interesting topic and I'm totally willing to be wrong, though.
I mean... I can see how... say... working out for like 7 hours isn't going to burn more fat because you have muscle, water, etc. But at the same time, we look at *real* starvation situations and while there is virtually no muscle, there is equally low fat. But there are definitely organs left. It would seem more reasonable to think "there is a point where your body is burning more water and muscle than fat". But an actual fat loss limit??
What real starvation situations are you looking at? When people die from starvation it's usually organ failure. A female at a clinic I was at had kidney failure and heart failure from eating to little.5 -
My basic education and consults with nutritionists are this: in order to lose weight you must eat less calories than you burn (ok that's the basic), don't eat less than 1200 calories on a regular basis because the human body needs this to survive and function, now for macros if you are trying to lose fat (not muscle) then make sure you are eating 1 gram of protein per pound of body weight, otherwise yes some of that weight loss will be muscle and not fat. Also if you cut back on carbs and see a dramatic weight loss that is more likely due to water weight than fat loss. It's not recommended to attempt to lose more than 2 lbs of weight per week, your body needs more calories the more active you are. So that means if you average a 1,000+ calorie deficit per day then you most likely will need to increase the calories you are consuming so that you can sustain you energy levels for your daily activities. From my research and educational background if you follow the basics above you'll be ok.
Not sure that it really answer the question you asked and honestly I'm not sure I completely understand the original post that you quoted. I would need more specifics from that poster: what do they mean by "a reasonable deficit"?
Check out the book "Burn the Fat, Feed the Muscle" by Tom Venuto0 -
Rebecca0224 wrote: »WendyLeigh1119 wrote: »nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
I agree, though this "fat loss limit per day" topic is new to me. It's an interesting topic and I'm totally willing to be wrong, though.
I mean... I can see how... say... working out for like 7 hours isn't going to burn more fat because you have muscle, water, etc. But at the same time, we look at *real* starvation situations and while there is virtually no muscle, there is equally low fat. But there are definitely organs left. It would seem more reasonable to think "there is a point where your body is burning more water and muscle than fat". But an actual fat loss limit??
What real starvation situations are you looking at? When people die from starvation it's usually organ failure. A female at a clinic I was at had kidney failure and heart failure from eating to little.
Because of a "fat burning time limit"? Preposterous. That's what the OP is about. Some sort of arbitrary "fat burn cut off" where fat would be left alone, but muscles and organs burned first?? No.4 -
Not first but the body does not burn just fat it also burns muscle when you are in a deficit and many factors determine how much muscle is burned.2
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WendyLeigh1119 wrote: »Rebecca0224 wrote: »WendyLeigh1119 wrote: »nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
I agree, though this "fat loss limit per day" topic is new to me. It's an interesting topic and I'm totally willing to be wrong, though.
I mean... I can see how... say... working out for like 7 hours isn't going to burn more fat because you have muscle, water, etc. But at the same time, we look at *real* starvation situations and while there is virtually no muscle, there is equally low fat. But there are definitely organs left. It would seem more reasonable to think "there is a point where your body is burning more water and muscle than fat". But an actual fat loss limit??
What real starvation situations are you looking at? When people die from starvation it's usually organ failure. A female at a clinic I was at had kidney failure and heart failure from eating to little.
Because of a "fat burning time limit"? Preposterous. That's what the OP is about. Some sort of arbitrary "fat burn cut off" where fat would be left alone, but muscles and organs burned first?? No.
I think you are misunderstanding.
It's known that muscle gets burned along with fat to some extent. How much varies based on a number of factors: how much fat do you have to burn (if a lot, less concern), are you eating a good amount of protein (more than the RDA to protect against muscle loss at a deficit -- around .8 g-1g/lb of LBM is often recommended as a result), are you doing strength exercises? And also how deep is the deficit? Higher deficits make muscle loss more likely.
Related to this is the idea that your body has a cap on how much fat it can burn daily. That's the 31 cal per lb of fat or whatever it is. It's not that after that you go straight to organs (I'm not actually concerned about organs unless one loses irresponsibly over quite a period of time), but you will be increasingly burning more muscle and you can't assume there's some unlimited amount of fat to lose so that you can drop 2 lbs of fat/day or whatever if you just exercise enough and eat less -- that kind of Biggest Loser fueled nonsense.
It's a pretty high number, anyway -- I think jemhh's point is really the key one. But pointing to anorexics or starving people generally doesn't support this idea that you can drop some unlimited amount of fat per day.13 -
The study that concluded 31 calories, per pound of fat, per day.
https://ncbi.nlm.nih.gov/pubmed/15615615
Sorry, don't have full access so this is just an abstract.
If you do some digging, Lyle Mcdonald looked at this study, and found it valid for the subject, which were limited to moderate or lower activity. He more or less said for those in that group, doing the math based on that formula and your personal body fat was a good guide to maximum deficit, but also added that it only applies for those in moderate or lower activity levels.
He essentially stated that those working out harder, and in particular lifting, could exceed that calorie burning limit, but also cautioned that even for people in that group, if they wanted a large deficit they should do it through additional exercise, not calorie restriction alone.
As for the question posted in the OP? Well true, or woo, depending on the context it was originally delivered in. I would suggest anyone with large deficits look into Lyle Mcdonalds work, as he was done quite a bit on the more extreme side of things, but the diets contain ideas that would help the average person losing weight from losing as much lean body mass as well.15 -
Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha0
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RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.4 -
RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.3 -
RAD_Fitness wrote: »RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.
How do you know they were?2 -
RAD_Fitness wrote: »RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.
Really not a good idea to make conclusions based on anecdotes.1 -
RAD_Fitness wrote: »RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.
Are we talking about the drug that causes people to cook to death? Rather be fat, thanks.6 -
WendyLeigh1119 wrote: »Rebecca0224 wrote: »WendyLeigh1119 wrote: »nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
I agree, though this "fat loss limit per day" topic is new to me. It's an interesting topic and I'm totally willing to be wrong, though.
I mean... I can see how... say... working out for like 7 hours isn't going to burn more fat because you have muscle, water, etc. But at the same time, we look at *real* starvation situations and while there is virtually no muscle, there is equally low fat. But there are definitely organs left. It would seem more reasonable to think "there is a point where your body is burning more water and muscle than fat". But an actual fat loss limit??
What real starvation situations are you looking at? When people die from starvation it's usually organ failure. A female at a clinic I was at had kidney failure and heart failure from eating to little.
Because of a "fat burning time limit"? Preposterous. That's what the OP is about. Some sort of arbitrary "fat burn cut off" where fat would be left alone, but muscles and organs burned first?? No.
No. Just that the body doesn't ONLY burn fat for energy. It also uses muscle, and the heart in particular is made of muscle. If you were able to do internal medical testing on those starving people who LOOK emaciated you'd find that their internal organs are also suffering. Most anorexic die of heart failure.3 -
PaulaWallaDingDong wrote: »RAD_Fitness wrote: »RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.
Are we talking about the drug that causes people to cook to death? Rather be fat, thanks.
Haha yeah I agree, I'm just saying, if it's possible to metabolize that much fat in a day, then the 31 calorie thing seems not high enough1 -
RAD_Fitness wrote: »PaulaWallaDingDong wrote: »RAD_Fitness wrote: »RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.
Are we talking about the drug that causes people to cook to death? Rather be fat, thanks.
Haha yeah I agree, I'm just saying, if it's possible to metabolize that much fat in a day, then the 31 calorie thing seems not high enough
A limit on the natural metabolic process of recovering stored energy from fat seems perfectly consistent from a drug that "anecdotally" just burns the fat (in the literal sense) and "cooks people to death." They're not the same thing. If the drug worked by making the energy in fat available for your body to use, it would just get stored again if it was more energy than your body required.3 -
RAD_Fitness wrote: »RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.
And are they certain the loss is entirely fat, no lean tissue at all? How do they know this?
Even if true (I'm skeptical of most anything, absent solid evidence), I wouldn't assume that that would imply that "it must be possible on your own as well".
Why take a risk on something as important to health as this, just to lose fast? Lean tissue is slow and difficult to regain. Exercise, adequate protein, and a moderate loss rate - those are conservative strategies that give the best odds of a good outcome.
Besides, huge deficits are harder for most people to sustain over the long haul - losing at a sustainable steady rate may actually result in faster actual loss than an aggressive rate that causes a person to fall off course repeatedly.
Around here, a common rule of thumb for moderate loss rate is no more than 1% of body weight per week, possibly a bit more at first if morbidly obese, less as you reach somewhere between 25-50 pounds above goal. I know if no targeted research that supports exactly this, but it's a common rough guide.4 -
Thanks for all the responses so far. I'll be checking out the links this afternoon! I'm not planning to go on an extreme aggressive diet btw ... I'm currently losing at 5 pounds a months and am happy with that - but had just never seen it stated before that there was a limit to how much fat could be lost a day and was curious.0
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nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
It doesn't cannibalize critical organs, it "cannibalizes" muscle which is not critical (well, SOME muscles are like your heart. The body taking energy from the heart after other lean tissue is gone is why many anorexics die of heart disease)1 -
nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
It doesn't cannibalize critical organs, it "cannibalizes" muscle which is not critical (well, SOME muscles are like your heart. The body taking energy from the heart after other lean tissue is gone is why many anorexics die of heart disease)
I'm not sure what the scare quotes are about. It's the right word.
I do agree that your body would cannibalize heart tissue if you were literally starving. This is basically just the observation that it is possible to starve to death.
What I'm saying is that the degree of caloric deficit doesn't seem likely to cause this. For instance, say a 500lb man fasts while walking 9 miles a day. That will be a very steep deficit. If you want to claim this man is at risk for losing heart tissue, we'll say in the 500-200 window just to be comfortable... I can't believe that without data. I would need some information about why you think that is true because, on it's face, it looks like a preposterous claim to me.1 -
nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
No, but it will cannibalize muscle tissue.0 -
lynn_glenmont wrote: »RAD_Fitness wrote: »PaulaWallaDingDong wrote: »RAD_Fitness wrote: »RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.
Are we talking about the drug that causes people to cook to death? Rather be fat, thanks.
Haha yeah I agree, I'm just saying, if it's possible to metabolize that much fat in a day, then the 31 calorie thing seems not high enough
A limit on the natural metabolic process of recovering stored energy from fat seems perfectly consistent from a drug that "anecdotally" just burns the fat (in the literal sense) and "cooks people to death." They're not the same thing. If the drug worked by making the energy in fat available for your body to use, it would just get stored again if it was more energy than your body required.
Yeah but that's not how it works.
It works by making your body less efficient at using ATP and excess energy is released as heat and as the dosage increases, the inefficiency increases as well, which is how overheating can occur and you can die from it. But your body constantly needs to create more energy so it is constantly metabolizing fat and again unable to use all the energy in normal functions.1 -
RAD_Fitness wrote: »lynn_glenmont wrote: »RAD_Fitness wrote: »PaulaWallaDingDong wrote: »RAD_Fitness wrote: »RAD_Fitness wrote: »Who's able to even go at a 31 calorie/pound per day deficit. Holy cow. I'd need to burn 7,800 calories to just eat 1,000 calories. Wonder how 3 days of that must feel haha
Lol. It's (supposedly) 31 calories per pound of body fat. For a 140 lb woman at 25% bf that's a 1085 deficit, which is stupidly steep, likely 40%+ of her TDEE. Even if the 31 calorie number is true, it's not reasonably sustainable for an extended period of time for many people.
Ohhh hahaha I see.
But there is a drug that anecdotally allows people to lose up to a pound of body fat a day, albeit with the possibility of death, but if your body is able to metabolize that much fat, then it must be possible on your own as well. The guys I've seen talk about it did not have much body fat to begin with, so they definitely were burning more than 31 calories per pound of fat.
Are we talking about the drug that causes people to cook to death? Rather be fat, thanks.
Haha yeah I agree, I'm just saying, if it's possible to metabolize that much fat in a day, then the 31 calorie thing seems not high enough
A limit on the natural metabolic process of recovering stored energy from fat seems perfectly consistent from a drug that "anecdotally" just burns the fat (in the literal sense) and "cooks people to death." They're not the same thing. If the drug worked by making the energy in fat available for your body to use, it would just get stored again if it was more energy than your body required.
Yeah but that's not how it works.
It works by making your body less efficient at using ATP and excess energy is released as heat and as the dosage increases, the inefficiency increases as well, which is how overheating can occur and you can die from it. But your body constantly needs to create more energy so it is constantly metabolizing fat and again unable to use all the energy in normal functions.
Is this drug legal?
If it is, please don't mention its name, I was just wondering.1 -
I'm the one who posted the excerpted comment in the OP, based on this question:
I want to maximize my weight loss. Should I eat back my excercise calories or stick to my set calories? What are the pros and cons? Do you eat your calories back?
My full response was:
If you go by the MFP recommendation and have your settings at "sedentary", you should absolutely eat back a portion of your exercise calories. Many people find that MFP, as well as other exercise estimates to be inflated, so they eat back 50-75% instead of all of them. Your goal should be to 'net' the recommended number that MFP sets for you, so if you're recommended to eat 1600 calories, but you burn 300 in exercise, you should eat at least some of those burned calories back in order to finish the day at close to 1600.
Losing weight very fast is not the same thins as losing fat. In order to lose fat, a reasonable deficit (which WILL seem to take more time) is a better solution. The body can only burn so much fat per day; after that any loss that you see will likely be muscle (after water weight). If you keep too steep of a deficit, you will lose muscle all over your body to include critical organs like your heart. If you keep it up for too long, you can do serious damage.
Another thing to consider is that when people attempt a too aggressive deficit, the tendency is that they burn out before reaching their goal and end up either stopping fat loss, or gaining fat back. In six months or a year, they end up back where they started and it takes that much longer to reach the ultimate goal. IMO, it's a better strategy to stick with a reasonable and realistic deficit from the start. You'll be happier during the process and end up more successful, probably in less time.
Remember - it's not about maximizing weight loss. Your goal should be to maximize FAT loss, and for that you have to take a slower approach.
I couldn't remember the theoretical limit of calories burned per pound of fat, although I thought it was lower than 31 (I thought I read 24 somewhere, so still on the higher range). Considering that the OP I was responding to didn't say what their stats were or how much they had to lose, I based my response on a general 'maximum weight loss does not equal maximum fat loss' response with an eye to caution at trying for a too high deficit and ignoring exercise calories altogether.4 -
nokanjaijo wrote: »nokanjaijo wrote: »I do not think your body will readily cannibalize critical organs if there are fat stores available. That strikes me as preposterous.
It doesn't cannibalize critical organs, it "cannibalizes" muscle which is not critical (well, SOME muscles are like your heart. The body taking energy from the heart after other lean tissue is gone is why many anorexics die of heart disease)
I'm not sure what the scare quotes are about. It's the right word.
I do agree that your body would cannibalize heart tissue if you were literally starving. This is basically just the observation that it is possible to starve to death.
What I'm saying is that the degree of caloric deficit doesn't seem likely to cause this. For instance, say a 500lb man fasts while walking 9 miles a day. That will be a very steep deficit. If you want to claim this man is at risk for losing heart tissue, we'll say in the 500-200 window just to be comfortable... I can't believe that without data. I would need some information about why you think that is true because, on it's face, it looks like a preposterous claim to me.
I think you're getting all caught up in cannibalization of organs from the get go...that wouldn't really happen to any significant extent until one was basically, no fat left, no muscle left, etc. This would happen much quicker in, say, a person who is already at a very low weight or underweight, but they have head problems and think they just need to lose more and more and more until they actually kill themselves.
From my understanding of this, the theoretical limit for fat oxidation in a 24 hr period is 31 calories per Lb of BF. As I understand from some of my reading, this is because you don't actually oxidize subcutaneous fat...subcutaneous fat must be converted by the body and turned into Triglycerides which enter the blood stream and at that point can be used for energy...one of the issues is that if the deficit is too steep, the body simply can't keep up with the conversion of fat to triglycerides to provide the energy.
IDK, this isn't something I think about too much and have only done a bit of research on...I'm not an idiot and have never run a stupidly steep deficit...I think it's pretty much common knowledge that it's not a good idea.
ETA: From a purely observational standpoint, it's pretty easy to see body composition wise...you can definitely tell who has lost more muscle than they otherwise would have had they kept a more reasonable deficit.6
This discussion has been closed.
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