For people with anorexia nervosa, gaining weight is scary.
Why do treatment providers put so much emphasis on weight gain? Why can’t treatment just focus on ways to feel less depressed, anxious, or obsessed with food?
The simple answer is that in the absence of getting to a healthy weight, lasting psychological improvement is unlikely. We know this – and other vital information about the effects of starvation – thanks to a group of men who came together for the sake of research in 1944.
In a landmark semi-starvation study, conducted by Ancel Keys at the University of Minnesota during World War II, the effects of starvation on the human body were evaluated to determine how to re-feed people who were starving in war-torn Europe. Thirty-six young men volunteered for the study. To participate, these men had to be physically and psychologically healthy. They were put on a very low-calorie diet for 24 weeks, with the goal of losing about 25% of their baseline weight. They underwent many physical, cognitive, and psychological tests so that researchers could evaluate the process and implications of starvation. (For information on a follow-up study published about a subgroup of Keys study participants, read here.)
Physical Effects of Starvation
Physically, during starvation, the men experienced symptoms also found in people with anorexia nervosa including:
- a lowering of body temperature (and noted that they felt cold much of the time)
- a decrease in heart rate, heart size, and lung capacity
- edema (swelling beneath the skin caused by a build-up of fluid), most commonly in the arms and legs
Psychological Effects of Starvation
The starving men also experienced profound psychological effects. Remember, to be a part of this study, the men had to be psychologically healthy and able to handle stressful situations. As a result, both the researchers and study participants were struck by the huge impact that starvation had on these men’s mental health.
They became depressed and irritable.
Study participants were grumpy with each other and with visiting family and friends.
They no longer laughed and relished life. They no longer enjoyed movies, except for the scenes of people eating.
Sexual desire decreased significantly.
Motivation to engage in work, mental tasks, and social life was very low.
The men became obsessed with food. They thought about it all the time, and some began collecting recipes and cookbooks.
During mealtimes, many of the men developed unusual eating behaviors, such as eating slowly and taking small bites, or mixing foods together in odd combinations.
A few of the men experienced episodes of binge eating and discontinued study participation.
What does it all mean for psychological functioning?
Many individuals with anorexia nervosa also report feeling depressed, apathetic, and preoccupied by thoughts of food. Many engage in eating rituals similar to those seen in the Keys study participants. The Keys study taught us that a lot (but certainly not all) of the psychological distress underweight individuals experience is because they are underweight and not eating enough. When people with anorexia nervosa improve weight, they become significantly less depressed, obsessional, and anxious.
Starvation Study Refeeding Process
At the end of the starvation period of the study, a 20-week refeeding period followed. During this phase, researchers systematically increased the men’s calories. Ultimately, they needed at least 4,000 calories per day to adequately regain the weight they had lost.
Treatment Implications for People with Anorexia Nervosa
This study provides valuable information about refeeding starved individuals with anorexia nervosa. The main take-home messages are:
- Restriction can lead to binge eating episodes.
- Weight gain requires a consistently high caloric intake.
- Mood, anxiety, and obsessional thinking will improve somewhat with normalization of weight to a healthy spot.
Being underweight is associated with a variety of disordered eating behaviors.
Taking a cue from the Keys study, inpatients at the Columbia Center for Eating Disorders typically consume around 4,000 calories daily during the renourishment process. One important difference between our inpatient unit and the Keys semi-starvation study is that patients here continue treatment until they hit a goal weight range (set with the help of medical doctors). Then, calories are adjusted, if it is appropriate to do so, to a level where the patient can maintain this goal weight range.
Where the Paths to Recovery Diverge
Of course, there are important differences between the participants of the Keys study and individuals with anorexia nervosa. For example, the men in the Keys study did not have a desire to lose weight. In fact, they desperately wanted to be able to eat more and gain back the weight they had lost. Therefore, while weight gain is necessary for recovery from anorexia nervosa, it is not sufficient; as weight improves, it is critical for people with anorexia nervosa to challenge their negative thoughts about body image and rigid beliefs about food.
Still, what we learned from the Keys study is where to start – and the first step in the successful treatment of anorexia nervosa is to climb out of the state of starvation.
Reference Keys, A., Brozek, J., Henschel, A., Mickelsen, O., & Taylor, H. L., The Biology of Human Starvation (2 volumes), University of Minnesota Press, 1950.

[…] disorder. It is by all accounts an extremely serious illness, associated with a variety of medical complications and amongst the highest mortality rates of all psychiatric disorders. Fortunately, […]
[…] distress that accompanies eating disorders can take a toll on the mind and body. It is not uncommon for people to experience moments of feeling helpless, confused, and […]
[…] nearly all body systems and can have a profound impact on personality and social identity. In the Minnesota Semi-Starvation Study, otherwise healthy, well-adjusted men became irritable, isolated, more somber, and more […]
[…] restriction – or “energy deprivation” – and the state of starvation seen in anorexia nervosa has profound consequences on the function and structure of the […]
[…] The severe malnutrition that results from anorexia nervosa leaves patients in extenuating circumstances both physically and psychologically. […]
[…] anorexia nervosa, suffer from the same physiological effects of malnutrition as women (in fact, the seminal study about these effects were done in men) and must, first and foremost, normalize their weight and physical health to have a chance at truly […]
[…] is no conclusive answer, but it has been suggested that for people with anorexia, the state of starvation significantly contributes to feeling depressed. Therefore, a crucial, necessary step in treating […]
[…] anorexia nervosa is associated with similar serious medical complications as anorexia nervosa. For example, individuals with either diagnosis can experience dangerous […]
[…] Social media makes it easy to keep unhealthy food obsessions alive. For example, popular recipe videos, for some people, may promote continued preoccupation with food, eating and calories. This is a modern-day equivalent to the hoarding of recipes and cookbooks experienced by starved individuals in the Keys semi-starvation study. […]
[…] The hallmark features of anorexia nervosa (AN) are a reduced consumption of calories that results in an abnormally low weight for adults or a failure for kids and teens to grow as they should, a fear of weight gain or becoming fat (or an inability to eat in a way that supports a healthy weight), and a distortion of or overemphasis on body weight and shape. People with this disorder commonly have difficulty recognizing the seriousness of not eating enough for their body’s needs. […]
[…] Minnesota Semi-Starvation Experiment, the landmark research study conducted during World War ll, unexpectedly taught the field of eating disorders a heck of a lot […]
[…] nervosa significantly impacts both the body and the mind. The low weight state leads to a variety of medical consequences, including bone loss (osteopenia) […]
[…] or somewhere in between, their eating disorder is a serious matter. It carries both medical and psychological consequences. The need to identify and address the problem, and then find help for it, must often […]
[…] Anorexia nervosa is associated with serious medical complications (implicating the cardiovascular system, hormones, and beyond). Ignoring or diminishing the severity of the illness can have profound physical and psychiatric consequences. […]
[…] and after weight has returned to normal. However, as anxiety and mood symptoms are also known to be exacerbated by the state of starvation, many people with anorexia nervosa experience an improvement in these symptoms with restoration to […]
[…] a starved state. This can include slowed heart rate, low blood pressure, low body temperature and other physical signs. Bloodwork will help evaluate signs of malnutrition, electrolyte imbalances that can occur if there […]