My comment is about the fact that when you see reality shows (I also have examples of a stronger nature) like "Survivor" all the participants lose weight at -- allow me to use a non-metric system -- an "insane" rate? How come prisoners of war kept on "bread and water" lose weight? Now, one might say that they do not end their captivity in "good health." But we are talking about losing weight, and since the dawn of time, calorie reduction has worked to lose weight.
What about bodybuilders? What do they do when they want to lose weight? Do they try the "watermelon" diet or choose brown rice instead of white rice? Apart from particular "manipulations" that occur in the last 1-2 weeks (depletion of glycogen and subsequent replenishment, cutting out water, salt, etc.), they simply eat less. And it works for every single bodybuilder, everyone loses weight.
How to lose more fat than other tissues requires a longer discussion, but how to lose weight is settled science.
And I would say the advice of "just eat less" doesn't work for probably 20-30% of people. Especially the very obese. You don't get to morbidly obese by "eating a little bit too much for 10 years." You don't fix it by eating a little bit less.
Obviously people can starve. There are 3 phases of starvation. Phase I is basically just "between meals" where the liver puts out some glycogen into your blood stream to maintain stable blood glucose.
Phase II is your body using your fat storage to provide energy via free fatty acids and ketone bodies. This can last, depending on the deficit and how much body fat you have, for weeks at a time. The record I've seen is over 400 days of a Scottish man going from over 400lbs to less than 200lbs.
Phase III starvation is when the body begins scavenging lean body mass for energy. This is Very Bad. This is why the POWs you see in photos look so emaciated and skinny. The body used all the fat and then it began using the protein.
The problem for dieting is that you can't just hang out in Phase II until you have six-pack abs. If your body cannot meet the energy requirements necessary from body fat then it'll go straight into Phase III. Many obese people have a "broken" metabolism in some way (how so is not very clear, that's what I'm trying to figure out). Despite carrying lots and lots of body fat around (I had over 100lbs of it on me!) they somehow couldn't "access" that energy. So the body went straight into Phase III with all the signals like reduced expenditure, lower body temperature, lower immune system, increased hunger.. and even if you could willpower though that for 100lbs, you'd lose a ton of protein as the body would use it for energy. So you'd probably die of organ failure before you lost the 100lbs. Unless you somehow managed to do what the Scottish man did. I've fasted for 10 days and I could absolutely not do 400 days.
Bodybuilders are a completely different topic than obese people, I think. They're typically already at a healthy fat level or below. So they really do have to force themselves to undereat and just minimize the muscle scavenging and maximize fat used for energy. But it's temporary for most, they do this in cycles before shows and photo shoots. No bodybuilder I know of had 100lbs of fat on him and then lost it for a show. They go from their walking-around-at 10-15% of body fat to 5-8%.
What I can tell you is that, according to the literature and the experience of millions of people:
- giving adequate protein and some stimulus (i.e., resistance training), even when diets are very restrictive (think 75% of basal metabolic rate), lean mass is largely preserved.
- if you read the Ancel Key's "starvation experiment", every single person lost weight according to predictions. To the point that when subjects did not lose weight according to the prediction, it was because they were (if I remember well) scavenging for food when walking outside. See also the more recent "potato experiment" or try the "burger experiment": two big mac with medium fries and diet soda per day (and nothing else) and a man 200+ pounds will lose weight (the two combined are around 1600-1800 calories).
- people were thinner in the past largely because of greater caloric expenditures (manual jobs, fewer cars, more time spent outside the house) and less calorie-dense and palatable food.
- bodybuilders or gym enthusiasts who are PED-free are normal people who track the calories and macro-nutrients and consistently provide stimulus to their muscle tissue in the direction of hypertrophy. They are not "special people". And while 5% body fat can be maintained only for a short time, 10-12% can be kept indefinitely, from a physiological point of view. Not from a culinary point of view, though, in the sense that you cannot have 3 portions of macaroni and cheese at lunch and dinner.
- there was a recent study on the metabolic differences of thin and less thin people. Thin people eat less, which is quite intuitive. It is very easy to consume calories nowadays: 200 for a snack, 300 for another, let me grab 4 chips and other 150 calories are coming in. Over time, they add up due to arithmetic and one finds themselves fat, while saying: "but I am not eating much!". Overeating is easy, and moving around less than in the past is easy as well. I was with a thin friend at lunch and I was ready to eat like the proverbial pig (say, 1000+ calories), and he ate toasted bread with some ham (maybe 500 calories). Big lesson there.
I recommend the books (and writing in general) of Lyle McDonald.
free link to calculate sedentary TDEE: https://tdeecalculator.net/
