What is the Minnesota Starvation Experiment?
CW: This article contains content that may not be suitable for those in recovery / living with an eating disorder - especially if you experience difficulty with calorie specifics. There is content describing food obsession, compensatory behaviours like purging, over-exercising, and restricting. Note there are limit graphics, there is the one directly below and a photograph of a man reading a cookbook (you cannot see his body.)
In December 2020, Tiktok had to launch an investigation into content promoting starvation and anorexia (1). It really seems like we’ve forgotten about the Minnesota Starvation Experiment from 77 years ago.
What is the Minnesota Starvation Experiment?
In November 1944 thirty-six young, healthy men who were conscientious objectors to the war were recruited for a study into prolonged famine like starvation. The study would look at the effects of such starvation on healthy men, and how various rehabilitation strategies negated any effects. The study had good intentions – the results would help allied relief for the famine victims at the end of World War 2.
Keep this in the front of your mind while reading this
These men were:
“Psychologically resilient” which meant they were screened to be of lesser risk of mental health conditions, stressful conditions, and were supposed to be quicker at “bouncing back” than other people.
Living in a time a lot freer from diet culture: they didn’t have 1000s of messages everyday about food, dieting, nutrition, good foods/bad foods. Can you imagine how tough of a time they would have had then!?
This one’s super important. The restriction put on the men wasn’t even as low as standard diets; the lowest restriction was 1800 calories per day. I can count at least 20 diets off the top of my head that are lower.
The experiment had four key phases:
12 weeks control: controlled diet, maintained ‘caloric balance’ to bring individuals close to their ‘ideal weight’. Physical and psychological tests undertaken.
24-week semi-starvation: dietary intake cut in half; participants lost around 25% of starting weight on average. Participants expected to walk 22 miles per week to expend 3500 kcal/day on average while eating 1800 kcal/day.
12-week restricted rehabilitation: four calorie groups, subdivided with protein and vitamin supplements.
8-week unrestricted rehabilitation: no restriction, but monitoring.
What were the outcomes?
The full report detailing the study sits at 1,385 pages over two volumes, so I’ll summarise below.
Reported decline in energy
Fights would occur when standing in line for food
Sexual interest dramatically reduced
Faces gaunt, skin yellow
21% reduction in strength using a back-lift dynamometer
Whitening of the eyeballs as the blood vessels around the eyes shrank
A lack of body fat meant sitting down was uncomfortable
Reduced heart rate – “The heart was consistently and markedly reduced in size by the starvation”
Physical effects associated with purging via vomiting, like blood shot eyes, Russel's sign, decaying teeth, painful throat
Increased need for sleep
Decreased tolerance for cold temperatures – requesting blanket s in summer
Dizziness, extreme tiredness, hair loss, muscle soreness, ringing in ears
Preoccupation with food during starvation and rehabilitation
Daydreams of food
Emotional euphoria followed by an emotional crash
Decline in concentration
The men didn’t see themselves as skinny – just that everybody else was too fat, what we now know as body dysmorphia
Personal motivation declined
Prefer to go to movies alone, recognise comedy but no compulsion to laugh
Resignation the typical emotion
Lack of interest in previous areas of significance e.g., politics and world events
Some withdrew from university classes as they had no energy to concentrate
Drinking water to feel fuller
Some men purchased / stole food
Some took to smoking / chewing gum until told they could not
Collecting of recipe books
As can be seen from the above the effects varied and, in some cases, can be deemed extreme. A few major takeaway effects included:
Preoccupation / obsession with food:
“Stayed up until 5:00 A.M. last night studying cookbooks. They are so absorbing I can’t stay away from them”
Many of the participants became very focused on food including daydreaming about food and collecting recipe books to look through during down time. Many of the participants lost interest in anything that wasn’t food oriented, withdrawing from university due to a lack of concentration.
2. Changes in mood
"When something good happened, we would explode with joy and when we were pessimistic, we were very depressed,"
"I had a very close friend there and often I'd speak sharply to him and I'd find myself going to him almost every night and apologising."
Many of the participants commented on small issues becoming big disputes that would cause upset and conflict.
During the study some participants stole and binged on food, leading to feelings of guilt and shame. Even after the study, the participants' social moods were more stable after 3 months of eating close to 3500 calories each a day, but some were binging to the point of sickness even 8 months later (and eating over double what most diets allow you!)
How was the refeeding period?
The participants were split into four groups, each with a differing caloric increase (ranging from 400 to 1600 calorie increases) following the starvation period. There was no improvement or signs of recovery until the calories were increased to about 4000 calories per day which allowed strength rebuilding.
It should be noted that during starvation body weight was down by around 25% on average, with that being around 70% body fat and 40% muscle. Upon refeeding participants did regain back to 100% of their original weight but 140% of their original body fat. It has been argued that this is the body protecting itself from future deprivation.
For some participants the rehabilitation period was the most difficult part of the experiment. After the 12-week restricted rehabilitation all the participants agreed they were not back to normal and the 8-week unrestricted rehabilitation was unstructured for the participants leading to some negative effects:
One of the men had to have his stomach pumped as the first day with no control he overate
One participant couldn’t satisfy his craving for food so was sick on the bus between meals
One described a “year-long cavity” that needed to be filled
The estimated ‘full recovery’ time ranged from 2 months to 2 years depending upon participants.
“Keys convinced twelve of them to stay on at the lab for another eight weeks so he could monitor them during an “unrestricted rehabilitation” phase. Left to their own devices, Keys observed these men consume over 5000 calories a day, on average. And on occasion, some of them feasted on as many as 11,500 calories in a single day. For many months, the men reported having a sensation of hunger they couldn’t satisfy, no matter how much they ate.“
Were there any long-term effects?
In 2003 nineteen of the original thirty-six were alive and shared about their experience. Some admitted they were haunted by a fear that food might be taken away from them again for many years following the study.
What does this have to do with my diet?
As you’d probably guess we can’t repeat the Minnesota starvation study today – it would be highly unethical. But we can take some lessons away from the study that apply to today’s diets.
Any period of malnourishment, from short term starvation to 6 months as in the study, or even longer as in the case of years long eating disorders can have an effect on the body and mind. Any of the symptoms above can occur to varying degrees – if you recognise any of them in yourself maybe your body is experiencing slight starvation.
And on the flip side, participants in the study took around a year to recover with some professional help and a focus on consuming calories.
Keys noted that after the starvation study calories must be abundant otherwise extra protein, vitamins and minerals will not help with rehabilitation.
I’ll leave you with this quote:
“I don't know many other things in my life that I looked forward to being over with any more than this experiment. And it wasn't so much … because of the physical discomfort, but because it made food the most important thing in one's life … food became the one central and only thing really in one's life. And life is pretty dull if that's the only thing. I mean, if you went to a movie, you weren't particularly interested in the love scenes, but you noticed every time they ate and what they ate.” - Harold Blickenstaff (2)