What happens when we don’t eat enough?
One of the most important studies used to inform eating disorder recovery was the Minnesota Starvation Experiment conducted in 1945. As World War II was ending, the University of Minnesota conducted this experiment to gain insights into the physical and psychological impact of starvation. At the time, they also wanted to learn about how to refeed soldiers and civilians that were starved during the war.
What was the experiment?
The experiment was organized by Dr. Ancel Keys and it involved 36 healthy male volunteers. The first 3 months of the experiment they were asked to eat normally. Then they entered a 6-month semistarvation period where they followed a restrictive diet of around half of their normal intake (1500-1800 kcal). After that they entered a 3-month rehabilitation phase where they were allowed to eat normally again.
Key findings
Impact on weight: The participants lost about 25% of their weight at the end of the semistarvation period with 40% loss of muscle mass. Weight restoration occurred slower than expected but most were able to regain the weight back eventually once the experiment ended. They noted some participants gained more weight than they lost and it took a while to settle back into their previous weights.
Impact on physical health: They found participants experienced decreased metabolism, heart rate, sex drive and body temperature. They experienced headaches, hair loss, weakness, fatigue, gut symptoms, and intense hunger.
Impact on mental health: Participants reported preoccupation and obsession with food. They also experienced increased apathy, anxiety, depression, and social isolation. Some showed personality changes and increased fixation on the body such as with body image or hypochondriasis. In the rehabilitation phase, mood stabilized after weight restoration.
Impact on eating behaviors: The study found starvation increased participants’ behaviors to promote satiation. During restriction, many would hoard food then binge food all at once. In the rehabilitation period, many participants engaged in binge eating of upwards to 7,000-10,000 kcal/day. Binging behaviors could last up to 5 months after starvation. 57 years after the experiment, they interviewed 19 men involved in the study and found that they still experience effects such as fears of not having food and/or disordered eating at some point in their lives.
Limits to this experiment
Obviously this study raised significant ethical concerns as it had a long-standing traumatic impact on the participants. The study also only included men- like most medical studies before the 90s. This means we are unsure if the exact findings could be generalized to other genders. For example, traditionally women had more social pressures to maintain a certain body image/figure, this could perhaps contribute to worse body image or restrictive symptoms than men in starvation.
How did the Minnesota Starvation Experiment inform eating disorders (ED) recovery?
There is a lot of parallel between starvation and symptoms of ED. Eating disorders are a complex subject which may involve “overeating” or restrictive eating behaviors, food preoccupation and developing certain rituals around food. Likewise, we learned that the participants in the Minnesota Starvation Experiment experienced similar psychological signs of distress when subject to starvation and calorie restriction.
While we can see how ED and disordered eating can push folks into starvation, the study actually showed that starvation itself can trigger eating disorder behaviors and disordered eating tendencies as well. This would explain nowadays why sometimes an innocent notion of wanting to lose weight can unintentionally spiral into a full fledged ED. In particular, the experiment’s participants were subject to a restricted diet of about 1500 calories per day at one point which is very similar to many weight loss and dieting plans today. This explains why such plans are generally unsustainable and can negatively affect one’s relationship with food.
The study also showed us that in order for physical and mental symptoms to improve, the participants had to restore weight. They found that restoring weight took a longer time and a lot more food than anticipated. It took at least 4000 kcal/day for these men to recover. This is why in ED treatment, we are focused on increasing energy intake first, before addressing any other ED symptoms.
The study saw that binge-eating is likely a direct consequence to food restriction, as binge eating subsided gradually as weight was restored. This makes a lot of sense as to why folks fall into the vicious cycle of yo-yo dieting only to notice rebound weight gain after each diet. If we don’t eat enough, the body will make sure we scream for it out of instinct.
All of this is to say The Minnesota Starvation Experiment continues to be a remarkable and grueling study in the field of nutrition research. Its findings provided valuable insights into the effects of starvation that somehow still echoes in our current diet culture. Today, the experiment continues to be a reference for researchers and clinicians of our understanding of eating disorders and its treatment.
Disclaimer: the information provided is not intended as medical advice or to diagnose or treat a medical disease. It is strictly for informational purposes. Consult with your medical provider such as a dietitian before implementing any dietary changes, the information provided does not replace medical advice provided by your healthcare provider.
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Research and blog assisted by Sharon Sun, RD
Reviewed and edited by Abby Hsiao, RD
Work Cited
Tucker, T. (2007). The great starvation experiment: Ancel Keys and the men who starved for science. U of Minnesota Press.
Kalm, L. M., & Semba, R. D. (2005). They starved so that others be better fed: remembering Ancel Keys and the Minnesota experiment. The Journal of nutrition, 135(6), 1347-1352.
Eckert, E. D., Gottesman, I. I., Swigart, S. E., & Casper, R. C. (2018). A 57-year follow-up investigation and review of the Minnesota study on human starvation and its relevance to eating disorders. Archives of Psychology, 2(3).
Keys, A., Brožek, J., Henschel, A., Mickelsen, O., & Taylor, H. L. (1950). The biology of human starvation, Vols. 1 & 2.
National Eating Disorders Association. (n.d.). What are eating disorders. Retrieved from https://www.nationaleatingdisorders.org/what-are-eating-disorders/
