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In early 1945, 36 American men lay in their bunks in a windowless room, each man alone with his thoughts as he tried to fall asleep despite the hunger that gnawed at his gut. Just a few weeks earlier, they had all been fit, healthy young men, eager to serve their country. But then their overseers had decreed that their rations were to be cut in half, and the men assigned to feed them had shown no mercy. Now they were so weak from hunger that they could barely roll over in their bunks. During the day, they tried to smile and laugh with each other to keep their spirits up, but at night the depression that accompanied starvation seeped in, telling them to give in, to give up. But the men soldiered on, despite the fact that they were not actually soldiers at all: they were pacifists who had volunteered to be starved for the sake of science.

In 1943⁠—over a year before the starvation study began⁠—the USA was struggling through its second year of fighting in World War 2. But Dr. Ancel Keys’ career was thriving. Not only had he accepted a position as head of the newly-established Laboratory of Physiological Hygiene at the University of Minnesota, but his work was being funded by the deep pockets of the U.S. Army. This support was thanks to Dr. Keys’ development of the infamous “K ration,” a pocket-sized packet of food containing 2,830 calories, 33 grams of protein, and most of the vitamins a soldier needed in a day. Despite its unpopularity amongst soldiers due to its overuse, Army officials had been so impressed with the K ration that they named Keys a special assistant to the Secretary of War and encouraged his research on the effects of nutrition and deprivation on the human body. It wasn’t just money that the Army was throwing Keys’ way⁠—they also provided him a steady source of healthy, young volunteers for his studies, drawn from the ranks of America’s conscientious objectors. These young men had refused to participate in combat due to their pacifist beliefs, and instead served their country through activities like firefighting, caring for the mentally ill, and maintaining National Parks as members of the Civilian Public Service, or CPS. Dr. Keys used them as free lab rats to study vitamin deficiencies, thirst, and heat stress.

Dr. Ancel Keys (Wikipedia)

Maintaining morale among the CPS volunteers proved challenging. They had registered as conscientious objectors in the face of skepticism and derision from friends and neighbors. They had volunteered for uncomfortable and even painful medical procedures to advance humanity’s understanding of the human body. They withstood extreme levels of cold, heat, moisture, and thirst in the pursuit of science. One experiment required volunteers to stay in bed for a month. Others measured the harmful effects of the absence of various vitamins in the volunteers’ diets. But all of the experiments they suffered through seemed to have only one purpose: to produce a stronger, fitter American soldier who could stay in the fight as long as possible. As much as the volunteers wanted to serve their country, this chafed against the pacifism they had already sacrificed so much for.

One of Keys’ lab assistants, Harold Guetzkow, a conscientious objector himself, sensed the increasing disgruntlement amongst the volunteers and approached Keys. As it turned out, Keys had also been growing restless with his experiments. While his work was contributing to the war effort, he wondered whether his research could serve a larger purpose: addressing the looming food crisis in Europe. The war was ravaging the landscape of Europe, destroying crops and rendering huge swathes of land unfarmable for the foreseeable future. Millions of people would soon be living in a state of famine. Assuming the Allies were successful in retaking Europe from the enemy⁠—and that was a big assumption⁠—the responsibility for refeeding millions of people would soon fall to the Allied militaries, and probably most heavily on the U.S. Army.

But the science of starvation was not well understood. What does a lack of calories do to the heart, the bones, the victim’s mental state? More practically, what is the best technique for refeeding a starving person⁠—slowly increasing their intake of calories, or providing them with as much food as they can gobble down? Is it important to administer supplements of vitamins or protein as they slowly regain their weight? Keys realized that he was in the perfect position to answer all these questions. He had a lab, he had plenty of volunteers, and he had the financial support of the US Army. As a bonus, the conscientious objectors that Keys would be starving for science would be motivated by the thought of starving children overseas, rather than the idea of helping the Army kill more people.

The Army approved Keys’ proposal for a year-long, comprehensive starvation study to begin in late 1944. Keys distributed a recruitment brochure to CPS posts across the country calling for volunteers, emblazoned with the title, “Will You Starve That They Be Better Fed?” Over two hundred conscientious objectors volunteered for Keys’ experiment. He selected 36, choosing single men of average weight and excellent physical and mental health. In particular, Keys screened for men who could put up with the stresses and cramped quarters of the experiment, and who expressed enthusiasm for overseas relief efforts. He didn’t want frustrated, unmotivated volunteers stirring resentment in the ranks or quitting partway through the experiment.

A recruitment brochure for the study

The 36 volunteers walked into Keys’ laboratory under the university’s football stadium on 19 November 1944. They all bunked together in a single windowless barracks in the lab, but they were allowed to travel around town and even to participate in university classes and activities. In fact, the human guinea pigs (as they called themselves) were required to walk at least 22 miles per week, although later in the experiment, all excursions had to include the presence of a “buddy” to discourage cheating. There was only one rule: the men could only eat the food provided by the laboratory, every gram of which was weighed and recorded before being portioned out to the volunteers.

During the first twelve weeks of the experiment⁠—the Control Phase⁠—the subjects were measured, weighed, poked, and prodded to determine their baseline health, weight, and calorie consumption. The men felt good. They were proud of the work they were doing, even though the real work hadn’t yet begun. They reveled in their long walks along the river to complete the required weekly 22 miles. A friendly competition sprung up among the subjects as the researchers tested their physical endurance with grueling runs on a treadmill. After a twenty minute uphill walk, each man was required to run at seven miles per hour on an uphill incline for five minutes, or until they collapsed. Twelve of the men were able to brag after the first test that they had lasted the entire five minutes.

Dr. Keys even brought in speakers and instructors to provide the men with 25 hours of instruction a week on sociology, political science, and language. This “relief academy” was meant to prepare the men to travel overseas to help the relief efforts in Europe, after the experiment and the war were over. It also helped to keep them entertained during the early portions of the experiment, and enabled the researchers to track their subjects’ anticipated mental deterioration later in the year. Some of the men took advantage of the free university tuition and took classes in French and law. One guinea pig joined a five-act campus theater production of Le Bourgeois Gentilhomme (“The Middle-Class Aristocrat”).

All too soon, the Control Phase ended and the Starvation Phase began. For the next 24 weeks, the volunteers’ calories were cut in half, and their health, mental state, and weight were continuously monitored. The effects of the calorie restriction on the men were, for the most part, unsurprising. Their body fat melted off, making sitting on an hard wooden or metal chair uncomfortably painful. Many of the men brought cushions to sit on during lectures from the guest speakers, and they usually dozed during the talks unless the lecturer mentioned food, at which point the hungry students sat up and listened intently. The lack of body fat also meant the men were cold all the time. Their average body temperature dropped by nearly a degree, and their average heart rate dropped to a plodding 35 beats per minute. The men lost all interest in women, instead spending their nights paging through cookbooks. Mealtimes, which delivered carefully measured quantities of foods like potatoes, cabbage, and bread, became the entire focus of their lives. They began to lose interest in the war and the world outside the lab.

Study subjects reclining on the grass

The psychological effects were perhaps the worst. Two men were dismissed from the experiment for cheating, one was dropped due to a medical problem, one for psychiatric issues, and one cut three of his own fingers off with an axe in a desperate attempt to be removed from the experiment without being seen as a quitter. As Keys’ experiment was leaking test subjects, the doctor had another problem to contend with: the wars in Europe and in Japan were coming to an end, concentration camps full of starving prisoners were being liberated, and Allied military efforts were turning towards famine relief, but the end of his experiment was not yet in sight. What good would his seminal work in starvation relief be, if he couldn’t publish it until long after the crisis was over?

Finally, for the last twelve weeks⁠—Restricted Rehabilitation⁠—the men were divided into four groups, each group having its calorie allowance increased by 400, 600, 800, or 1200 calories. Some were given vitamin or protein supplements, to measure the effects of different refeeding techniques. A number of the men stayed on for eight more weeks of “Unrestricted Rehabilitation,” where they could eat as much as they wanted, but were still closely monitored and studied.

One of the key discoveries of the experiment was that vitamin and protein supplements had very little effect on patient outcome when rehabilitating starving victims. The most important factor in recovery speeds is simply the number of calories they are provided during refeeding. Keys also found that despite their weakness, starvation victims can continue to consume calories by mouth without feeding tubes or other equipment. Many starvation relief efforts spent significant time and money shipping supplements and feeding apparatus overseas, so this was an important result.

Keys’ experiment ended in December 1945 with 32 subjects (including the man who cut off his own fingers, who begged to be allowed to finish the experiment). While it took several more years for Keys to analyze and publish the official results of his work, he encouraged his assistant, psychologist Harold Guetzkow, to publish a 70­-page illustrated booklet for relief workers in January 1946. Men and Hunger: A Psychological Manual for Relief Workers summarized the results of the experiment and provided practical instructions how to best rehabilitate a starving population. Finally, in 1950, Keys published the two-­volume, 1,385-­page The Biology of Human Starvation. It is particularly useful today in the treatment of eating disorders, because it details the mind-altering effects of starvation. These symptoms must be treated first in eating disorder patients, before the underlying psychological causes of the disorder can be identified and managed.

Subject Dan Miller, pictured left during the starvation phase, and right during the recovery phase

But the same global conflict that had motivated the Minnesota Starvation Experiment also resulted in the end of such extreme scientific experimentation on human test subjects. As Keys was writing up his results, the Doctors’ Trial in Nuremburg was revealing the horrific experiments conducted by Nazi researchers on prisoners. The world’s scientific community vowed that such atrocities could never be committed again, and developed the Nuremburg Code, and later the Helsinki Declaration, outlining the ethical limits of medical experimentation on humans. Despite the voluntary nature of the Minnesota Starvation Experiment, under these new standards, it became unlikely that such a study could ever be conducted again. Therefore, Dr. Keys’ experiment can never be replicated, and The Biology of Human Starvation will remain the seminal work on the subject of starvation.