Food Deprivation and Behavior

Updated: May 5


We’ve discussed Ancel Keys on this blog before (see April 24th’s post on the Seven Countries Study). Keys studied a variety of topics throughout his career in science, but one of his earliest contributions related to how starvation affects not only our bodies, but our brains and our behavior.

After World War II, captured prisoners of war began returning to the United States as well as countries throughout Europe. As a consequence of their imprisonment, many were severely malnourished. It was observed that many of these individuals became critically ill when returned to a normal diet immediately upon re-entering society. We now know this to be a result of “re-feeding syndrome”, a potentially fatal condition in which metabolic disturbances can lead to a dramatic change in electrolyte balances.

Keys devised an experiment to learn more about the causes of this phenomenon. In 1944, he began a selection process for choosing subjects. He selected from a group of conscientious objectors to military service. The men actually selected for the study weren’t randomly chosen. From well over 100 candidates, the 36 chosen met the highest standards of physical and psychological testing. The study took place on the campus of the University of Minnesota, in rooms underneath the bleachers of the football stadium.

It’s at this point that I should mention that this study occurred long before the advent of ethics review boards for research on collegiate campuses. Feel free to read up on the Stanford Prison Experiment to learn how those finally came to be. In reality, Keys’ starvation study should have never occurred considering the physical and psychological impact on the participants. The information, nevertheless, is valuable.

Each of the men in the study was held to a strict limit of 1500 calories per day. Many reading this may think “Wait a minute, 1500 calories isn’t starving. Is it?” For a young, relatively active male, it’s far below their needs. In fact, it’s about half of what’s needed for a young male body to function normally. And the changes this limitation imparted on the men were striking.

The physical changes were probably more expected than some of the others. Weight loss occurred as the men lost, on average, around 25% of their original weight. There were corresponding drops in body temperature, heart rate, respiration, and metabolic rate. By the end of the six months of semi-starvation, their metabolism had dropped by an average of 40%. Other physical symptoms included edema (swelling), headaches, dizziness, poor motor control, hair loss, inability to maintain body heat, and visual and auditory disturbances.

Calorie deprivation notably affected the men’s moods and personalities as well. Anxiety, depression, and even outbursts of anger developed in men who previously were very stable in their temperament. One unfortunate individual chopped off three of his fingers in an act of self-harm due to his deep depression. He was subsequently released from the study.

Binge eating and an intense pre-occupation with food developed in the men. Thoughts and discussions about food dominated the men’s daily routine, while interest in non-culinary topics waned or disappeared. Hoarding of food-related items such as coffeepots, hot plates, and utensils was observed. The re-feeding process, which occurred over a 12 week period, was intended to be structured, but many of the men struggled to moderate their intake. Several had daily intakes of 8,000 to 10,000 calories per day, despite efforts from the researchers to keep the men on a strict plan. Some ate at such a pace that they made themselves sick, only to start eating again soon after. This pattern is not dissimilar from that which is often observed in individuals with bulimia nervosa. It took about five months for the men in the study to normalize their eating behaviors, which corresponded with a normalization of their weight.

Keys’ study was not intended to address knowledge relating to eating disorders, but it has given clinicians in that field a source of information to share with malnourished patients to help explain some of their feelings and behaviors. After all, the men in this study had very few, if any, pre-existing conditions. They were chosen as the best of the best both physically and psychologically. It seems safe to say that the changes in the bodies and in their behavior were the result of malnutrition. Once the men were re-fed and back at a healthy weight, their behavior did return to normal and they went on to live healthy, productive lives (although one of them was forced to do so with three fewer fingers). If you’re curious, their metabolism went back to normal as well. For eating disorder patients, particularly those with anorexia, the lesson is that food is indeed medicine. If nutrition and weight are restored to baseline, mood and behavior are likely to improve as well.

There are lessons here for dieters and those with weight loss goals as well. Weight loss can certainly be an appropriate goal but, although many need to be more mindful of choices and portions, deprivation diets are not the answer.


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