Eventually, five of the subjects succumbed to what Keys and his colleagues called “character neurosis,” to be distinguished from the “semi-starvation neurosis” that all the subjects experienced; in two cases, it “bordered on a psychosis.” One subject failed to lose weight at the expected rate, and by week three was suspected of cheating on the diet. In week eight, he binged on sundaes, milk shakes, and penny candies, broke down “weeping, [with] talk of suicide and threats of violence,” and was committed to the psychiatric ward at the University Hospital. Another subject lasted until week seven, when “he suffered a sudden ‘complete loss of willpower’ and ate several cookies, a bag of popcorn, and two overripe bananas before he could ‘regain control’ of himself.” A third subject took to chewing forty packs of gum a day. Since his weight failed to drop significantly “in spite of drastic cuts in his diet,” he was dropped from the study. For months afterward, “his neurotic manifestations continued in full force.” A fifth subject also failed to lose weight, was suspected of cheating, and was dropped from the study.

With the relaxation of dietary restriction, Keys avoided the dietary overindulgence problem that had beset Benedict’s subjects by restricting the rehabilitation diets to less than three thousand calories. Hunger remained unappeased, however. For many of the subjects, the depression deepened during this rehabilitation period. It was in the very first week of rehabilitation, for instance, that yet another subject cracked—his “personality deterioration culminated in two attempts at self-mutilation.”

Even during the last weeks of the Minnesota experiment, when the subjects were finally allowed to eat to their hearts’ content, they remained perversely unsatisfied. Their food intake rose to “the prodigious level of 8,000 calories a day.” But many subjects insisted that they were still hungry, “though incapable of ingesting more food.” And, once again, the men regained weight and body fat with remarkable rapidity. By the end of the rehabilitation period, the subjects had added an average of ten pounds of fat to their pre-experiment levels. They weighed 5 percent more than they had when they arrived in Minneapolis the year before; they had 50 percent more body fat.

These two experiments were the most meticulous ever performed on the effects on body and mind of long-term low-calorie diets and weight reduction. The subjects were selected to represent a range of physiological types from lean to overweight (albeit all young, male, and Caucasian). They were also chosen for a certain strength of character, suggesting they could be trusted to follow the diets and remain dedicated to the scientific goals at hand.