According to a doctor who has been researching obesity for more than half a century (!) and who is quoted in a New York Times health column today, no diet is better than any other, a calorie is a calorie, and the only formula for controlling your weight, or losing some, is to eat less and exercise more.
Here is a small excerpt of what Dr. Jules Hersch told the interviewer, or click on this link to read it all. "The study" refers to a research finding that seemed to indicate that those on a high-fat, Atkins type diet burned more calories than those eating a more balanced diet.
Q: Should people stay on diets that are high in fat and protein if they want to keep the weight off?
What they did in that study is they took 21 people and fed them a diet that made them lose about 10 to 20 percent of their weight. Then, after their weight had leveled off, they put the subjects on one of three different maintenance diets. One is very, very low in carbohydrates and high in fat, essentially the Atkins diet. Another is the opposite — high in carbohydrates, low in fat. The third is in between. Then they measured total energy expenditure — in calories burned — and resting energy expenditure.
They report that people on the Atkins diet were burning off more calories. Ergo, the diet is a good thing. Such low-carbohydrate diets usually give a more rapid initial weight loss than diets with the same amount of calories but with more carbohydrates. But when carbohydrate levels are low in a diet and fat content is high, people lose water. That can confuse attempts to measure energy output. The usual measurement is calories per unit of lean body mass — the part of the body that is not made up of fat. When water is lost, lean body mass goes down, and so calories per unit of lean body mass go up. It’s just arithmetic. There is no hocus-pocus, no advantage to the dieters. Only water, no fat, has been lost.
The paper did not provide information to know how the calculations were done, but this is a likely explanation for the result.
A: So the whole thing might have been an illusion? All that happened was the people temporarily lost water on the high-protein diets?
Perhaps the most important illusion is the belief that a calorie is not a calorie but depends on how much carbohydrates a person eats. There is an inflexible law of physics — energy taken in must exactly equal the number of calories leaving the system when fat storage is unchanged. Calories leave the system when food is used to fuel the body. To lower fat content — reduce obesity — one must reduce calories taken in, or increase the output by increasing activity, or both. This is true whether calories come from pumpkins or peanuts or pâté de foie gras.