Why Fast Weight Loss Leads to Failure

If you’ve tried “quick weight loss” diets, you know the truth: when you lose
pounds quickly, you put them back on just as fast. Worse yet, when you end
a diet, you usually gain back more weight than you lost. That’s because your
body reacts to an intense period of semistarvation by making you crave large
amounts of “forbidden” high-calorie, high-fat, high-carbohydrate foods.
Thousands of years of evolution have taught your body that starvation is
dangerous. Because of this, you react to a restricted diet in the same way as
your Neanderthal ancestors did: you grow ravenously hungry, because your
body wants you to store extra fat. Worse, your body goes into survival mode,
slowing your metabolism, hoarding fat, and even putting on water weight to
make weight loss harder. Your body doesn’t know that your food shortage is
artificial; it thinks there’s a real danger that you’ll starve to death, and it pulls
out all the stops in an effort to save you.
Even when you “wise up” and stop dieting, it takes time to reset your
metabolism so you can burn calories more easily. Chronic dieting sends your
body the message “Conserve body fat at all costs!” To reverse this process, you
need to convince your body that the danger of starvation is over—and that
won’t happen overnight.
In addition, you need to allow time for both your body and your mind to
recover from the stress of dieting. New research shows that stress itself can
put on pounds, which is another reason the ordeal of dieting usually results,
ironically, in added weight and inches. To understand this pattern, let’s look
at how stress changes your body in ways that promote weight gain—and why
it takes time to reverse this process.