The Negative Effect of Diet on Weight Loss
The Negative Effect of Diet on Weight Loss
Weight loss attempts in the United States have emphasized dietary restriction with continued sedentary living. This combination has led to consistent failure. Weight loss with this method is temporary, and most of these weight watchers lose and gain weight many times during their life. The eating patterns established during the diet period are short-lived.
People in the United States have been, and continue to be, obsessed with losing weight. At any given time, about 40 percent of women and 25 percent of men are attempting to lose weight for reasons of physical appearance or health. Unfortunately, 90 percent to 95 percent of all dieters regain all or most of the weight that they lost within five years. Eat-less approaches to weight loss and permanent weight control have not worked and probably never will. Inexplicably, people continue to utilize weight-loss strategies that have failed them in the past. New attempts may feature new “diets,” but calorie restriction remains the method of choice.
It is time to forget dieting as an effective weight-loss technique. The appropriate nutritional approach emphasizes sensible modifications in eating behavior that can be followed for a lifetime, not for just a few weeks or a few months. This means a nutritional approach that emphasizes a low-fat, high complex-carbohydrate style of eating. This, combined with sensible, progressive, and consistent exercise for a lifetime, should produce the permanent weight loss and control that people want.
Metabolism is affected adversely by calorie restriction. In its quest for homeostasis (the tendency to maintain a constancy of internal conditions), the body adapts to the reduced-calorie intake by lowering the metabolic rate. This effort to economize in response to less food intake is a survival mechanism that protects people during lean times. Because the body learns to get by with less, the difference narrows between calories eaten and the calories it needs. This defense mechanism is what has made possible the survival of prisoners of war in concentration camps. Individuals who voluntarily reduce their food intake have the same result: a drop in RMR. As RMR decreases, so, too, does the effectiveness of dieting.
Regular vigorous exercise has the opposite effect: It accelerates the metabolic processes and increases body temperature during and after physical activity. The RMR might remain elevated for some time after exercise. Under exercise conditions, the body is spending kcals rather than hoarding them.
Metabolism represents the body’s production of heat. On the one hand, exercise increases heat production, oxygen demand, and calories used. Dieting without exercise, on the other hand, reduces metabolic heat production and, consequently, the number of calories burned. Some studies have shown that several weeks of a very low calorie diet (fewer than 800 kcals/day) resulted in a drop of heat production to 80 percent of the predict level. This is counterproductive because weight loss under this regimen becomes more difficult. As the number of calories needed decreases, the difference between those needed and those consumed becomes smaller. The more restrictive the diet, the greater is the loss of lean tissue and metabolic heat production.