Why does weight loss not follow?

The first question is: When the consumption of calories is reduced, why does weight loss not follow? Actually, weight loss does occur, but only temporarily. This is, in fact, where Newburgh and Johnson went wrong, in that they collected their data over much too short a period of time. The phenomenon works like this:

Suppose that an individual needs 2,500 calories a day and that, over a long period, he consumes accordingly. If, suddenly, the ration of calories drops to 2,000, the body will draw on an equivalent quantity of stored fat to compensate and weight loss will be seen to occur. However, if from now on the daily intake of calories is limited to 2,000, instead of the 2,500 previously consumed, the body's survival instinct comes into play. It quickly adjusts its energy requirements to match the level of calorie intake: if it is only given 2,000 calories, it will only use up 2,000 calories. Weight loss will quickly cease. But the body does not stop there. Its instinct for survival will lead it to take greater precautions yet, and lay down reserves for possible future need. If from now on it is supplied with 2,000 calories, it will simply reduce its energy needs to, say, 1,700 calories and store the other 300 in the form of body fat.

So this is how we end up achieving the very opposite of the result we were aiming for. Paradoxically, although the subject is eating less, he will gradually put weight back on again.

In practice, the human body, constantly driven by its survival mechanisms, behaves no differently from the starving dog which buries its bone. Despite what we might think, it is when the dog is not fed regularly that it reverts to its inborn instincts and buries its food, saving it for the day when it may otherwise go hungry.

How many of you, I wonder, have fallen victim at one time or other to this unfounded theory of balancing calories? You will certainly have come across obese people who were actually starving themselves to death. This is especially common among women. Psychiatrists' consulting-rooms are full of women being treated for depression induced by trying to follow such a diet. They have become dependent on this vicious circle, knowing that breaking away from it will only entail putting back on more weight than they have lost.