In 1944, 36 Conscientious Objectors to the war were voluntarily starved in a highly controversial experiment conducted by Ancel Keys at the University of Minnesota. The study aimed to gain insight into both the physiological and psychological effects of caloric restriction on previously healthy individuals, as well as helping to guide the Allies re-feeding efforts for those subjected to famine during the war.

The experiment comprised of a control period, in which the participants were fed a normal diet, followed by a 6 month semi-starvation period, during which their daily caloric intake was halved. During the re-feeding period, various recovery diets were used, involving differing energy intakes and varying nutrient levels, to determine the most effective re-feeding strategies. There followed a period of unrestricted but closely monitored food intake.

Many are shocked to discover that a study such as this took place as recently as the 1940s, and with good reason, as it would surely not be permitted to run now, especially as those leading the study could give no guarantees that there would be no long-term effects to the participants. The men suffered severe emotional and physical distress, including two subjects experiencing psychotic disturbances, both during and following the study.

However, ex-participants have pointed out that they never felt in any danger during the experiment; they were very closely monitored throughout and even appeared apologetic, wishing people to know that they acknowledged the difference between their supervised hunger and that of those starving elsewhere in the world. They were all volunteers, under no illusions as to what they were signing up for, with the freedom to leave the study whenever they wished.

The research led to huge insights into the effects of starvation. The volunteers all experienced many symptoms of eating disorders, such as hoarding recipes, preoccupation with food, social withdrawal and even self-mutilation; one participant cut off three fingers with an axe, although he claimed he was unsure whether this was intentional. This has led to improvements in treatments for both sufferers of eating disorders and those who have experienced chronic starvation for other reasons, as well as insight into the idea that eating disorders could be caused by starvation and weight loss.

The conventional wisdom that people’s set weight can be altered by dieting has also been shown as false by the study; the volunteers all regained to their initial weight plus 10 per cent during re-feeding, before gradually dropping back to their pre-experiment weight. Notably, the study revealed the amazingly adaptive nature of the human body in potentially fatal circumstances. Starvation leads to a heightened interest in food, to the detriment of other, less immediately vital occupations. This makes perfect evolutionary sense in light of the primitive struggle for survival.