Chapter 3 focuses on the fallacy of the “calories in, calories out” theory of weight loss. Experiments reveal that the body compensates for extreme caloric reduction by expending less energy. The subjects of the Minnesota Starvation Experiment of 1945, for example, experienced a decrease in resting metabolic rate and a drop in body temperature in response to caloric deprivation (37). Their blood pressure and physical endurance also dropped. The psychological effects were equally striking: the subjects were unable to concentrate, experienced constant hunger, and became disinterested in everything, save food. In short, their bodies adapted to caloric reduction by reducing expenditure. Adaptation started with a rapid drop in body fat. After the experiment ended, however, the subjects regained weight quickly until they were heavier than they were at the outset.

Caloric-reduction diets are comparable to the Minnesota Starvation Experiment. Dieters lose weight by eating less, prompting their metabolisms to slow, which leads to a plateau in weight loss and eventually to weight gain. A 2006 National Institutes of Health study of 50,000 post-menopausal women conclusively undermined the approach to weight loss. A third of the women followed a low-fat diet, participated in educational sessions, and were encouraged to exercise. A control group was told to eat as they normally did and received minimal educational support.