Minnesota Starvation Experiment
The Minnesota Starvation Experiment, also known as the Minnesota Semi-Starvation Experiment, the Minnesota Starvation-Recovery Experiment and the Starvation Study, was a clinical study performed at the University of Minnesota between November 19, 1944 and December 20, 1945. The investigation was designed to determine the physiological and psychological effects of severe and prolonged dietary restriction and the effectiveness of dietary rehabilitation strategies.
The motivation of the study was twofold: First, to produce a definitive treatise on the subject of human starvation based on a laboratory simulation of severe famine and, second, to utilize the scientific results produced to guide the Allied relief assistance to famine victims in Europe and Asia at the end of World War II. It was recognized early in 1944 that millions of people were in grave danger of mass famine as a result of the conflict and information was needed regarding the effects of semi-starvation — and the impact of various rehabilitation strategies — if post-war relief efforts were to be effective.
The study was developed in coordination with the Civilian Public Service (CPS) and the Selective Service System and utilized thirty-six men selected from a pool of over 100 CPS volunteers. The study was divided into three phases: A twelve week control phase where physiological and psychological observations were collected to establish a baseline for each subject; a twenty-four week starvation phase, over which period the caloric diet of each subject was dramatically reduced causing each participants to lose approximately 25% of their pre-starvation body weight; and, finally, a recovery phase where various rehabilitative diets were used to renourish the volunteers. Two subjects were dismissed for failing to maintain the diet restrictions imposed during the starvation phase of the experiment, and the data for two others was not used in the analysis of the results.
In 1950, Ancel Keys and his colleagues published the results of the Minnesota Starvation Experiment in a two-volume, 1,385 page text entitled The Biology of Human Starvation (University of Minnesota Press). While this definitive treatise came too late to substantially impact the post-war recovery efforts, preliminary pamphlets containing key results from the Minnesota Starvation Experiment were produced and used extensively by aid workers in Europe and Asia in the months following the cessation of hostilities.
Ancel Keys was the lead investigator of the Minnesota Starvation Experiment. He was responsible for the general supervision of the activities in the Laboratory of Physiological Hygiene and was directly responsible for the X-ray analysis and administrative work for the project. Keys founded the Laboratory of Physiological Hygiene at the University of Minnesota in 1940 after leaving positions at Harvard’s Fatigue Laboratory and the Mayo Clinic. Starting in 1941, he served as a special assistant to the U.S. Secretary of War and worked with the Army to develop rations for troops in combat (K-rations). Keys served as Director for the Laboratory of Physiological Hygiene for 26 years and retired in 1972 after a distinguished 36 year career at the University of Minnesota.
Olaf Mickelsen was responsible for the chemical analyses conducted in the Laboratory of Physiological Hygiene during the Starvation Study, as well as the daily dietary regime of the CPS subjects including the supervision of the diet kitchen and its staff. During the study he was an associate professor of biochemistry and physiological hygiene at the University of Minnesota. He received his Ph.D. in Biochemistry from the University of Wisconsin in 1939.
Henry Longstreet Taylor had the major responsibility of recruiting the 36 CPS volunteers used in the Minnesota Starvation Experiment and maintaining the morale of the participants and their involvement in the study. During the study, he collaborated with Henschel on conducting the physical performance, respiration and postural tests. He received his Ph.D. at the University of Minnesota in 1941 and joined the faculty at the Laboratory of Physiological Hygiene where he held a joint appointment with the Department of Physiology. His research concentrated on problems in cardiovascular physiology, temperature regulation, metabolism and nutrition, aging and cardiovascular epidemiology.
Austin Henschel shared the responsibility of screening the CPS volunteers with Taylor for selection in the Minnesota Starvation Experiment and, in addition, had charge of the blood morphology and scheduling all the tests and measurements of the subjects during the course of the study. He was a member of the faculty in the Laboratory of Physiological Hygiene and the Department of Medicine at the University of Minnesota.
Josef Brozek was responsible for the psychological studies during the Starvation Study, including the psychomotor tests, anthropometric measurements and statistical analysis of the results. Brozek received his Ph.D. at Charles University in Prague, the Czech Republic, in 1937. He emigrated to the United States in 1939 and joined the Laboratory of Physiological Hygiene at the University of Minnesota in 1941 where he served in a succession of posts over a 17 year period. His research in the Laboratory of Physiological Hygiene concerned malnutrition and behavior, visual illumination and performance, and aging.
 Participant volunteers
An essential ingredient to the successful execution of the Minnesota Starvation Experiment was the availability of a sufficient number of healthy volunteers willing to subject themselves to the year-long invasion of privacy, deprivation, physical and mental hardship necessary to complete the study. From the outset, the experiment was planned in cooperation with the Civilian Public Service and the Selective Service System with the full intention of utilizing volunteers selected from the ranks of conscientious objectors already inducted into public wartime service. Keys obtained approval from the War Department to select participants from the Civilian Public Service.
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 detailed examination. Drs. Taylor, Brozek 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 that showed 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. The subjects were all white males with ages ranging from 22 to 33 years old. Of the thirty-six volunteer subjects, twenty-five were members of the Historic Peace Churches (Mennonites, Church of the Brethren and Quakers)
The thirty-six CPS participants in the Minnesota Starvation Experiment were: William Anderson, Harold Blickenstaff, Wendell Burrous, Edward Cowles, George Ebeling, Carlyle Frederick, Jasper Gardner, 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.
 Goals and methods
The primary objective of the Minnesota Starvation Experiment was to study in detail the physical and psychological effects of prolonged, famine-like semi-starvation on healthy men and their subsequent rehabilitation from this condition. To achieve these goals, the 12-month study was parsed into four distinct phases:
Control Period (12 weeks): This was a standardization period when the subjects received a controlled diet of approximate 3,200 calories of food each day. 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;
Semi-Starvation Period (24 weeks): During the 6-month semi-starvation period, each subject’s dietary intake was cut to approximately 1,800 calories per day. Their 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.
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 that received distinct protein and vitamin supplements regimes. In this manner, the clinical staff examined various energy, protein and vitamin strategies for renourishing the subjects from the conditions of famine induced during the semi-starvation period.
Unrestricted Rehabilitation Period (8 weeks): For the final rehabilitation period, the 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 at approximately the same loss rate tracking the prediction weight loss curve defined by the equation:
Wx = Wf + K • (24 - t)2 ,
where Wx is the subject’s weight at time t and Wf is the final target body weight after 24 weeks. For each subject, the individual factor, K, is determined by the formula,
K = W0/100 • P/242 ,
where W0 is the subject’s initial weight at the beginning of the starvation phase and P is the total desired target weight loss. This quadratic formula for determining calorie intake is called the Key’s Formula and is still used today in the therapeutic treatment of nutritional disorders.
Throughout the duration of the study, each man was assigned specific work tasks, was expected to walk 22 miles each week and required to keep a personal diary. An extensive battery of tests was routinely administered including the collection of metabolic and physical measurements, X-ray examinations, treadmill performance, and intelligence and psychological evaluation.
The full report of results from the Minnesota Starvation Experiment was published in 1950 in a two-volume, 1,385 page text entitled The Biology of Human Starvation (University of Minneapolis Press). The fifty chapters of this treatise contain an extensive analysis of the physiological and psychological data collected during the study together with a comprehensive literature review.
Among the many conclusions from the study was the confirmation that prolonged semi-starvation produces significant increases in depression, hysteria and hypochondriasis as measured using the Minnesota Multiphasic Personality Inventory (MMPI), a standardized test administered during the experimental period. Indeed, most of the subjects experienced periods of severe emotional distress and depression. There were extreme reactions to the psychological effects during the experiment including self-mutilation (one subject amputated three fingers of his hand with an axe, though the subject was unsure if he had done so intentionally or accidentally). Participants exhibited a preoccupation with food, both during the starvation period and the rehabilitation phase. Sexual interest was drastically reduced and the volunteers showed signs of social withdrawal and isolation. The participants reported a decline in concentration, comprehension and judgment capabilities, although the standardized tests administered showed no actual signs of diminished capacity. There were marked declines in physiological processes indicative of decreases in each subject’s basal metabolic rate (the energy required by the body in a state of rest) and reflected in reduced body temperature, respiration and heart rate. Some of the subjects exhibited edema (swelling) in the extremities, presumably due to the massive quantities of water the participants consumed attempting to fill their stomachs during the starvation period.
One of the crucial observations of the Minnesota Starvation Experiment discussed by a number of researchers in the nutritional sciences — including Ancel Keys — is that the physical effects of the induced semi-starvation during the study well approximates the conditions experienced by patients afflicted with a range of eating disorders such as anorexia nervosa and bulimia nervosa. Indeed, it has been postulated that many of the profound social and psychological effects of these disorders may actually result from symptoms of undernutrition and that recovery depends critically upon physical renourishment as well as psychological treatment.
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