Minnesota Starvation Experiment

The experiment was planned in cooperation with the Civilian Public Service (CPS) and the Selective Service System, using volunteers selected from the ranks of conscientious objectors who had been inducted into public wartime service. Ancel Keys obtained approval from the War Department to select participants from the CPS. Availability of a sufficient number of healthy volunteers willing to subject themselves to the year-long invasion of privacy, nutritional deprivation, and physical and mental hardship was essential for the successful execution of the experiment.

In early 1944, a recruitment brochure was drafted and distributed within the network of CPS work camps throughout the United States. Over 400 men volunteered to participate in the study as an alternative to military service; of these, about 100 were selected for examination. Drs. Taylor, Brožek, and Henschel from the Minnesota Laboratory of Physiological Hygiene traveled to the various CPS units to interview the potential candidates and administer physical and psychological tests to the volunteers. Thirty-six men were ultimately selected who demonstrated evidence of the required mental and physical health, the ability to get along reasonably well within a group while enduring deprivation and hardship, and sufficient commitment to the relief and rehabilitation objectives of the investigation to complete the study. All subjects were white males, with ages ranging from 22 to 33 years old.

Of the 36 volunteer subjects, 15 were members of the Historic Peace Churches (Mennonites, Church of the Brethren and Quakers). Others there included Methodists, Presbyterians, Baptists, and one of each who was Jewish, Episcopalian, Evangelical & Reformed, Disciples of Christ, Congregational, and Evangelical Mission Covenant, along with two participants without a declared religion.[5]

The 36 CPS participants in the Minnesota Starvation Experiment were: William Anderson, Harold Blickenstaff, Wendell Burrous, Edward Cowles, George Ebeling, Carlyle Frederick, Jasper Garner, Lester Glick, James Graham, Earl Heckman, Roscoe Hinkle, Max Kampelman, Sam Legg, Phillip Liljengren, Howard Lutz, Robert McCullagh, William McReynolds, Dan Miller, L. Wesley Miller, Richard Mundy, Daniel Peacock, James Plaugher, Woodrow Rainwater, Donald Sanders, Cedric (Henry) Scholberg, Charles Smith, William Stanton, Raymond Summers, Marshall Sutton, Kenneth Tuttle, Robert Villwock, William Wallace, Franklin Watkins, W. Earl Weygandt, Robert Wiloughby, and Gerald Wilsnack.

The 12-month clinical study was performed at the University of Minnesota between November 19, 1944 and December 20, 1945. Throughout the duration of the study each man was assigned specific work tasks, was expected to walk 22 miles (35 km) each week and required to keep a personal diary.[6] An extensive battery of tests was periodically administered, including the collection of metabolic and physical measurements; X-ray examinations; treadmill performance; and intelligence and psychological evaluation. The study was divided into four distinct phases:

1. Control Period (12 weeks): This was a standardization period when the subjects received a controlled diet of approximately 3,200 calories of food each day. The diet of the subjects who were close to their "ideal" weight was adjusted so as to maintain caloric balance, while the diets of the underweight and overweight individuals was adjusted so as to bring them close to their ideal weight. On average, the group ended up slightly below their "ideal" weight.[3]^: 74 In addition, the clinical staff of the Laboratory of Physiological Hygiene routinely conducted a series of anthropometric, physiological and psychological tests designed to characterize the physical and mental health of each participant under normal conditions.
2. Semi-Starvation Period (24 weeks until July 28, 1945): During the 6-month semi-starvation period, each subject's dietary intake was immediately cut in half to about 1,560 calories per day. His meals were composed of foods that were expected to typify the diets of people in Europe during the latter stages of the war: potatoes, rutabagas, turnips, bread and macaroni. On July 30, 1945, a photo published in Life Magazine showed the shirtless bony participants.[7]
3. Restricted Rehabilitation Period (12 weeks): The participants were divided into four groups of eight men; each group received a strictly-controlled rehabilitation diet, consisting of one of four different caloric energy levels. In each energy-level group, the men were further subdivided into subgroups receiving differing regimens of protein and vitamin supplements. In this manner, the clinical staff examined various energy, protein and vitamin strategies for re-nourishing the subjects from the conditions of famine.
4. Unrestricted Rehabilitation Period (8 weeks): For the final rehabilitation period, caloric intake and food content was unrestricted but carefully recorded and monitored.

During the starvation period, the subjects received two meals per day designed to induce the same level of nutritional stress for each participant. Since each subject had distinct metabolic characteristics, the diet of each man was adjusted throughout the starvation period to produce roughly a 25% total weight loss over the 24-week period.

The researchers tracked each subject's weight as a function of time elapsed since the beginning of the starvation period. For each subject, the weight versus time plot was expected—as well as enforced—to form a particular curve, the prediction weight-loss curve, whose characteristics were decided before the commencement of the experiment. The postulated curves turned out to be quite predictive for most subjects. If a subject did veer off his curve in any given week, his caloric intake for the next week would be adjusted, by varying the amount of bread and potatoes, to bring him back to the curve; however, the required adjustments were usually minor.[3]^: 75 The shapes of the curves were chosen "based on the concept that the rate of weight loss would progressively decrease and reach a relative plateau" at the final weight.[3]^: 74

For each subject, the weight vs. time curve was taken to be quadratic in time (in fact, an upward-opening parabola) with the minimum located at 24 weeks, at which point the weight is supposed to be equal to the final target body weight (the minimum is where the curve has zero slope; this corresponds to the "plateau" mentioned above). Mathematically, this means that the curve for each subject was given by

$${\displaystyle W(t)=W_{f}+K\,(24-t)^{2},}$$

where ${\displaystyle t}$ is the time (measured in weeks) elapsed since the beginning of the starvation period, ${\displaystyle W(t)}$ is the subject's weight at time ${\displaystyle t}$, and ${\displaystyle W_{f}}$ is the final weight that the subject was supposed to reach at the end of the 24-week period. The constant ${\displaystyle K}$ is determined by the requirement that ${\displaystyle W(t=0)}$ be the initial weight ${\displaystyle W_{i}}$, i.e. by solving

$${\displaystyle W_{i}=W_{f}+K\,(24-0)^{2}}$$

for ${\displaystyle K}$; this gives

$${\displaystyle K={\frac {W_{i}-W_{f}}{24^{2}}}}$$

.

The authors expressed this in terms of the percent total weight loss ${\displaystyle P}$,

$${\displaystyle P=100\times {\frac {W_{i}-W_{f}}{W_{i}}}}$$

(which, as stated above, was supposed to be about 25% for all subjects), obtaining

$${\displaystyle K={\frac {P}{100\times 24^{2}}}\,W_{i}}$$

.