[lolo_]

Are you sure about that? The body is not as simple as you assume, and weird stuff happens that makes literally no sense based on a simple energy in/energy out equation that can't only be explained by self-delusion.

It's funny how much weight loss is an ideological issue to usually quite logical people - don't assume you know this is impossible simply because you have a model in your head that says so.

EDIT: When I say self-delusion here I am referring to the apparent self-delusion of the author that the parent implies - to say you are only consuming 800kcal when there is an assumption that that MUST result in weight loss leaves only self-delusion as an explanation. My point is that there might be other factors (Emphasis on MIGHT...)

[CydeWeys]

Extraordinary claims require extraordinary evidence. And that is quite the extraordinary claim. Why are you so quick to believe something that is so obviously self-delusion, especially when it has never been duplicated in a laboratory? When scientists look into these kinds of claims it always turns out to be the case that the person is eating significantly more than they have claimed. Always.

[glenra]

Wait, what do you mean the claim "has never been duplicated in a laboratory"? The article was about EXACTLY THAT THING.

A dozen former Biggest Loser contestants went into a laboratory for a few days for a study in which they had their metabolism analyzed and it was verified that six years after losing weight on the show, all their metabolic rates were substantially reduced - by an average of 500 calories/day - from what would be normal for someone their weight.

In the context of this study result, a small woman failing to lose weight on an 800-calorie/day diet should not constitute an extraordinary claim.

(Doing the math: imagine her normal metabolism level might previously have required 1200 calories/day. Subtract ~500 due to having dieted, add ~100 for her "hour of exercise", and we're at ~800/day.)

[tomp]

If their metabolic rates were reduced by 500 from a high level (> 2500/day) that doesn't mean you can generalize this effect to people with BMR of 1200.

[JoeAltmaier]

Nevertheless, physics is NOT violated during dieting. Its a fact of physics that energy in/energy out must add up to energy gain/loss in the system. Lets stop arguing about that.

The likely issue is, cheating on the diet. Sure, eating limited calories at a meal is a good idea. Its also necessary to avoid adding 300-1000 kC with that fast-food burger after work or that donut at the meeting. Its so easy to do; it explains all the "I limited my calories and didn't lose weight!" claims. Simplest answer is often correct answer.

[lolo_]

I'll reply to all the dissenting comments just here to avoid duplication and since you were actually civil about it.

Yes that is the most likely answer I agree, however it doesn't make it the ONLY one. I have dieted using a 'food diary' and been amazed at how many calories you can eat/drink without realising it, it's really quite something.

HOWEVER, if she's so serious as to exercise that much, and knows the calories and it's at that low a level, it seems the error bars would likely preclude this.

I've noticed weird results when I've dieted where the 'energy equation' just does not match reality when I have dieted STRICTLY using a food diary and known-calorie food/drink. The 'dieting plateau' is famous and encountered by many so maybe there are more factors here.

Factors that might be at play (other than self-delusion):

1. Water/body fluid retention - This can vary quite a bit and is often (apparently) the explanation for dramatic results at the beginning of a diet. Water is dense enough for this to cause there to appear to be no weight change. In this case, the body fat _would_ be being used by the body as an energy source it just wouldn't show up in weight changes.

2. Inaccurate scales - It's surprising how often bathroom scales can be significantly off. Usually they are consistent + their delta, however maybe she measured on 2 different scales before and after (seems unlikely given how often we dieters like to check)

3. Use of muscle mass as an energy source - This can and does happen, though as I understand it usually as a 'last resort' by the body.

4. Reduced body temperature/energy usage - The body is capable of reducing energy used in starvation situations (though it renders you not feeling great often), this could happen here.

5. Change in efficiency of energy extracted from food - The body is complicated, it's not obvious that energy extracted from food will always remain the same.

6. Difference in diet composition - calories aren't the entire answer as some food is more easily digested than other food, and some types of food are more likely to result in weight gain than others.

7. Hormonal changes - Hypo and hyper-thyroidism can change body mass accumulation without ANY change in food intake, so this could easily apply to other hormonal changes.

8. Constipation - It sounds silly, but perhaps more retention of feces in the system could result in apparent lack of weight change.

9. Change in weather - Perhaps a hotter climate requires less heating and hence less energy usage by the body?

My principle point here is that things are just not as simple as energy in -> energy out - yes 'basic physics' holds that has to be an equilibrium, however you might not be measuring what these are correctly. A car must maintain an equilibrium too, but the type of car, its condition and what you do with it significantly varies the energy it requires despite the same distances being traversed.

[JoeAltmaier]

All sound true (except #7 - no possibility of accumulating mass without mass input) and a good starting point for a sensible conversation about diet. Water retention alone is probably responsible for almost all the perceived irregularities, IMO.

[nabla9]

OK, so she has shown us that people cam survive with 800 kcal per day and not lose weight.

If she can do that, African famines are hoaxes and UN has been fooling us all this time.

[AlexandrB]

> OK, so she has shown us that people cam survive with 800 kcal per day and not lose weight.

Only for several months while (probably) leading an otherwise sedentary lifestyle. Still remarkable, but a far less impossible feat.

[lolo_]

Your conclusion doesn't follow, there's nuance here.

She claimed it over 3 months, it might just be errors in measurement, water retention can make a big difference, there might be muscle mass loss (small amount, countered by water retention perhaps), etc. (see my other comment for some other potentials.)

Let's not just assume our model is definitely correct because it correlates to energy conservation - energy conservation assumes we know exactly energy in/out and that weight is a good measurement of the balance of the two and that we are measuring it accurately.