As World War II drew to a close, news media flooded the U.S. with horrific accounts of starved populations and refugees in war-torn nations abroad. Ancel Keys, one of history's most influential nutrition researchers, conceived of a study to provide data for relief workers. Initial findings were first published in Men and Hunger: A Psychological Manual For Relief Workers
. Rather than focusing simply on the nutritional requirements for re-feeding a starving person, he wanted to offer insight on how starvation (or in this case, "semi-starvation") alters
"the changes in motivation, then the behavioural consequences of the physical changes, and finally, the emotional, intellectual, and social changes which so profoundly influence the personality."
The volunteer subjects were all conscientious objectors who were eager to help the war effort. "Our friends and colleagues in other places were putting their lives on the line," said Samuel Legg, subject No. 20, in an interview 60 years later. "We wanted to do the same." Out of the hundreds who volunteered, 36 were deemed mentally and physically healthy enough to participate. They had basic daily work assignments, were required to walk 22 miles a week, and keep a diary. But aside from mealtime, there were no restrictions placed on their social lives.
The experiment began with a 12-week control period, wherein the men were fed approximately 3,200 calories a day. (Throughout the experiment, rations varied slightly for each subject, depending on individual metabolic factors.) At the end of the control phase, their calories were cut by approximately 50% and the six-month semi-starvation period began.