Are calories all that matter?

[The SkepDoc]

the person in question was on a 500 calorie diet a day, she lost some weight but then her body adjusted to this calorie intake level and she lost no more weight.

Now you've really got me intrigued. I went to an online resting metabolic rate calculator which estimates that for my age, height, weight and sex, my body would burn 1178 calories a day if I did nothing but breathe. It doesn't seem reasonable to me to think that I could cut down to 500 calories a day and not continue to lose weight indefinitely, even at absolute bed rest, and I presume the person you are talking about had a higher level of activity. I understand that the body adjusts its resting metabolism somewhat to compensate for a lower calorie intake, but I find it hard to believe that it could compensate that much. I found one estimate that 16% is the maximum reduction in BMR for metabolically active tissues obtained by starvation diets. I know there are testimonials for people who say they only ate 500 calories a day and didn't lose weight, but I have not been able to find any scientific confirmation where those claims were tested with adequate controls. Do you know of any such?

I have seen patients in the hospital who failed to lose weight on a 500 calorie diet, and in every case it turned out that someone was bringing food to them without their doctors' knowledge. I remember one patient who swore he was sticking strictly to the diet but was caught buying fistfuls of candy bars downstairs in the canteen.

I'm thinking that the victims of concentration camps and famines amply refute your claims. When severe calorie restriction was enforced in those situations, their weight did not stabilize. They continued to lose weight and starved to death.

This issue is particularly interesting in the light of longevity research. Severe calorie restriction with adequate nutrition, the so-called longevity diet, has been shown to increase life span in animals and is looking like it might be more promising for humans than any other longevity treatment, although the data aren't in yet. There's a fascinating article about this at: http://www.scientificpsychic.com/health/crondiet.html

Your statement that you value your personal experience above research is a pre-scientific attitude. I'm surprised to see it on this forum. Science can be wrong temporarily, but it has built-in self-correcting mechanisms. Personal experience is far more likely to be wrong, and science is the only possible corrective.

 

[Pup]

Now you've really got me intrigued. ... I know there are testimonials for people who say they only ate 500 calories a day and didn't lose weight, but I have not been able to find any scientific confirmation where those claims were tested with adequate controls. Do you know of any such?

What he said.

At what point did the person's weight stabilize? It was at something most people would consider "fat," I assume, otherwise the diet would have been considered successful.

If this is a rare genetic ability, we'd expect to see a certain proportion of concentration camp survivors come out of the camps overweight, and some survivors of African famines would be chubby.

If it's due solely to the choice of foods, the knowledge of how to maintain weight on 500 calories would be of tremendous help in planning for emergency survival situations or donating food to famine-struck areas.

If there are truly people who can remain overweight on 500 calories a day, it may be frustrating for them, but the knowledge of how to do it would be lifesaving for others.

 

[casebro]

In a somewhat related vein, I'm feeling so much better since I cut the gluten from my diet that I have been exercising for the first time in 10 years. I've cut calories, I think. I've put on ten pounds though. It had me puzzled. Then I realised that fat is almost pure, but muscles are 66% water. So, if I worked off five pounds of fat, replacing it with five pounds of protein, which neccessitated ten pounds of water, I would have gained the ten pounds.

Too bad it has been so long since I had my body fat content checked, so I can't prove it. My muscles do seem to be building up myoglobin to the point of making me anemic though. That shows on blood tests.

Also, I am overlean as much as overfat. With 230 pounds of lean mass, I just don't need any more muscle mass. I do welcome the fitness though.