More troubling were the psychological effects. The men became depressed, lethargic and irritable. They threw tantrums. They lost their libido. They thought obsessively about food, day and night. The Minnesota researchers called this “semi-starvation neurosis.” Four developed “character neurosis.” Two had breakdowns, one with “weeping, talk of suicide and threats of violence.” He was committed to the psychiatric ward. The “personality deterioration” of the other “culminated in two attempts at self-mutilation.” He nearly detached the tip of one finger and later chopped off three with an ax.

When the period of imposed starvation ended, the subjects were allowed to “refeed.” At first they were allowed to eat more calories, but restricted as to how much. A subset under continued observation was then allowed to eat to satiety, which was surprisingly hard to achieve. The men consumed prodigious amounts of food, up to 10,000 calories a day. They regained weight and fat with remarkable rapidity. After 20 weeks of recovery, they averaged 50 percent more body fat than they had when it began — “post-starvation obesity,” the researchers called it.

Implicit in many discussions of how best to lose weight is the assumption that hunger, which is a consequence of caloric deprivation, is not an issue. Health and government organizations tell the obese and overweight, who now make up just over two-thirds of our adult population, to do what the study’s subjects did: Eat less, cut back on calories.

That advice implies that the ensuing hunger will be an easily bearable burden (no depression, lethargy, irritability — no tantrums, please!). And bearable not just for 24 weeks, but a lifetime. The Minnesota experiment tells us that when semi-starvation ends, the refeeding period will not end well.

This issue of how to diet, and how to lose weight, was in the news again recently when a study was published by researchers at the National Institutes of Health. The researchers confined their obese subjects (nine women, 10 men) to a hospital ward and then put them on diets that approached semi-starvation, feeding them an average of more than 820 fewer calories a day than they needed to maintain their weight. They averaged about 1,920 calories a day, but one diet was composed of foods that were 29 percent carbohydrates and 50 percent fat — the carb-restricted diet — and the other was composed of foods that were 71 percent carbohydrates and only 8 percent fat — the fat-restricted diet.