In the 1940s, a groundbreaking scientific study known as the Minnesota Starvation Experiment was conducted to understand the effects of prolonged semi-starvation and how to best refeed those affected by famine. Though the name sounds extreme, the conditions were carefully controlled in a university setting—not a cruel trial, but a humanitarian effort to support post-WWII recovery. Today, this study is often referenced in discussions about extreme dieting, eating disorders, and metabolic adaptation. Here’s a breakdown of what it was, what participants were fed, and how the researchers tracked it all.

What Was the Minnesota Starvation Experiment?

Conducted between 1944–1945 by Dr. Ancel Keys at the University of Minnesota, the study aimed to:

• Understand the physical and psychological effects of semi-starvation.
• Develop effective strategies for rehabilitating war victims suffering from famine.

Participants:

• 36 healthy, young, male conscientious objectors to WWII (who volunteered as an alternative to combat service).
• All participants were physically and mentally healthy at the start of the study.

The experiment had three phases:

1. Control phase (12 weeks) – normal eating to establish baseline data.
2. Semi-starvation phase (24 weeks) – calorie restriction.
3. Rehabilitation phase (12+ weeks) – controlled refeeding.

What Were They Fed Exactly?

During the semi-starvation phase, the goal was to simulate the wartime diet of civilians in Europe. Participants were given roughly 1,570 calories per day—sometimes as low as 1,500 depending on individual needs and adjustments.

The Diet Included:

• Potatoes
• Turnips
• Cabbage
• Dark bread
• Macaroni
• Very limited meat and dairy
• Minimal fat, and almost no added sugars

This was a high-starch, low-protein, low-fat diet. The meals were intentionally bland, repetitive, and lacking in nutrient diversity. While the inclusion of bread and vegetables met basic caloric targets, the extremely limited quantity of meat is worth highlighting.

The Role of Meat — And What Happens Without It

One of the most important nutritional deficits in the experiment was the lack of adequate animal protein, especially from meat. Protein from meat is rich in essential amino acids, iron, vitamin B12, zinc, and other critical nutrients involved in:

• Maintaining muscle mass
• Supporting brain function and mood regulation
• Producing hormones and neurotransmitters
• Fueling immune system response
• Facilitating oxygen transport in the blood (via iron and B12)

These young, active men were not only restricted in calories—they were deprived of dense, bioavailable sources of nutrition. Plant-based sources of protein like bread and potatoes do not contain complete amino acid profiles or sufficient quantities of critical micronutrients, especially for bodies under physical stress.

Many of the physical and mental breakdowns the men experienced—fatigue, depression, anxiety, obsessive thoughts, cold intolerance, and even psychosis—may have been worsened by protein and micronutrient deficiencies, not just calorie restriction.

In fact, anemia and impaired cognitive function are known symptoms of B12 and iron deficiency, both of which are primarily found in red meat and organ meats. The near absence of meat in the experimental diet likely accelerated both physical degradation and mental instability.

How Was It Tracked?

The study was extremely detailed and scientific in its tracking. Here’s how researchers monitored the men:

1. Daily Weigh-ins & Body Measurements

• Weight, body fat, and muscle loss were tracked regularly.
• Body temperature, heart rate, and metabolic function were recorded.

2. Food Logs

• Every meal was weighed and recorded.
• Participants ate under supervision to ensure full compliance.

3. Psychological Testing

• Mood, behavior, cognitive function, and emotional stability were monitored.
• Participants frequently reported depression, irritability, anxiety, and obsession with food.

4. Activity & Physical Performance

• Men were required to walk 22 miles per week.
• Strength and endurance were tested regularly.

5. Medical Exams

• Doctors closely tracked cardiovascular health, digestion, and hormonal function.
• Several participants experienced edema (swelling), fatigue, and even episodes resembling psychosis.

What Were the Results?

The effects of 6 months on a 1,570-calorie/day, meat-deficient diet were dramatic:

• Average body weight dropped by 25%.
• Participants developed obsessive thoughts about food, social withdrawal, emotional distress, and loss of libido.
• Many reported difficulty concentrating, sleeping, and functioning.
• One man cut off part of his own finger—though it’s debated whether this was intentional or due to mental strain.

The absence of adequate meat likely amplified these effects. Without enough complete protein or key nutrients like B12 and zinc, the body’s physical and mental systems can quickly begin to falter—especially under stress and activity.

In the rehabilitation phase, it became clear that refeeding took time. Simply returning to a normal calorie intake didn’t lead to immediate recovery—psychological and physiological symptoms lingered. Some participants reported food obsession and emotional distress for months afterward, showing how deep the impacts of undernourishment can run.

Why Does It Matter Today?

The Minnesota Starvation Experiment is still cited in discussions about:

• The dangers of extreme calorie restriction (such as very-low-calorie diets).
• How starvation impacts mental health and food obsession.
• The long-term effects of dieting and metabolic slowdown.
• The physiology of eating disorders like anorexia nervosa.

It also serves as a reminder that calories alone aren’t the whole picture. The quality of those calories matters just as much as the quantity. A low-calorie, high-starch, meat-deficient diet—like the one used in the experiment—can quickly lead to breakdowns in both physical strength and emotional well-being.

Despite its age, the study remains one of the most comprehensive examinations of how the human body and mind respond to starvation—and how the absence of nutrient-dense foods like meat can dramatically accelerate decline.

Final Thought

The Minnesota Starvation Experiment wasn’t about weight loss—it was a humanitarian effort to understand famine. Ironically, many of its lessons now serve as a warning against the very same restrictive eating behaviors that modern diet culture often promotes. The takeaway: food is fuel, not the enemy, and the body needs enough of it—including complete proteins and essential nutrients found in meat—to function, thrive, and stay sane.