How dieting can make you depressed as well as fat

A cautionary tale of calorie restriction brought to you by conscientious war objectors in Minnesota

A study recently published in the British Medical Journal suggests that there is a link between low-calorie diets and depressive symptoms.

This observational study is essentially just an analysis of the dietary habits and depression scores of over 28,000 adults in the US. Although the results tell us nothing definitive about cause and effect, they do provide scope for further investigation.

But is there any need? It’s already been done, and at great personal cost to those involved.

An experiment took place in the 1940s that revealed in detail what happens to both mind and body when energy intake is restricted for an extended period of time.

It was not the sort of study that would gain ethical approval today. And to carry out a risk assessment would have taken longer than the trial period. But hey, those were the days, when nobody cared about ethics or risky outcomes.

The aim of the Minnesota Starvation Experiment was to gain insight into the physical and psychological effects of food restriction in starved, war-weary civilians in Europe. World War II brought hunger to millions, and scientists were keen to know how to help people recover from the effects of starvation.

This experiment had two important findings. The first was that eating less leads to weight loss in the short term, but weight gain in the long term, which is depressing enough.

The second was that you risk not only becoming depressed but also somewhat out of your mind.

Thirty-six men were involved. Many came from the Historic Peace Churches (Mennonite, Brethren, and Quaker), and all expressed strong convictions about nonviolence, but wanting to make a meaningful contribution during the war.

Participation in the trial was offered as an alternative to military service, and although over 400 men volunteered, only those who were deemed to have the mental and physical capacity to see through the experiment were selected.

There’s a red flag, if ever there was one.

In November 1944, these 36 young men took up residence in buildings of the University of Minnesota football stadium, which effectively served as a secure clinic for a year.

First, they completed a twelve-week control phase, during which they were allowed a normal diet consisting of 3,200 calories a day.

The control phase was followed by a six-month period of ‘semi-starvation’, with each man allowed 1,570 daily calories, split into two meals, breakfast and lunch.

When the six months were up, there was a rehabilitation period of three months, when the men were allowed 2,000 to 3,200 calories daily.

Finally, there was an 8 week stretch of unrestricted calorie intake.

The food they ate throughout was the food available during the war: potatoes, root vegetables, bread and macaroni. Every week the men worked 15 hours in the laboratory, walked 22 miles, and spent 25 hours engaged in various educational activities.

If you consider that the recommended daily energy intake for men is 2,500 calories you’d be forgiven for thinking that these volunteers were hardly starved. Quite a cushy alternative to fighting a war, you might think.

Not so cushy, as it turned out.

The basal metabolic rate of these men decreased by 40%. Muscle mass also decreased by 40% and the pace of weight loss eventually ground to a halt.

Psychologically, the men experienced apathy, irritability and depression. There were some disturbing changes in personality, when they became possessive about their food, guarding it from others. Some started chewing gum to excess, sometimes two or three sticks at once until their mouths became sore. Others took up smoking to get some relief from their hunger.

They became self-absorbed and anti-social, lost their sense of humour and grew obsessed with food and eating.

Nearly 20% showed ‘severe character neurosis’, with two of the participants becoming borderline psychotic.

Dieting had driven them crazy with hunger, had altered their personalities and left them exhausted.

So you’d assume that arriving at the final, ‘all you can eat’ phase of the experiment must have felt like ascension into food heaven to those poor wretches. But cruelly, it turned out to be a descent into a lower circle of hell, with some of the men describing this phase as even more torturous than the calorie restriction period.

They could not stop eating, but still felt hungry all the time. They ate almost continuously - over 5,000 and sometimes as many as 10,000 calories per day - and consequently gained weight. This weight was in the form of fat, not muscle, and most of the men completed the trial weighing 10% more than they did at the beginning.

The war ended in Europe on May 8th 1945, but not for these volunteers who were only halfway through the starvation phase. For them, the battle with food restriction didn’t end until October that year.

In 2003–2004, 18 of the original 36 participants were still alive and agreed to be interviewed about their experiences.

Although none of them regretted going through with the trial, they never forgot how brutal it was. Even when it ended, it was far from over. One of the participants recalled being hospitalised to have his stomach pumped after an overeating episode. He wasn’t the only one who took to binge-eating - another remembered being sick on the bus after eating too much. Another participant described the year following the end of the experiment as a ‘year-long cavity’ that had to be filled.

Reading about this experiment in a variety of journals I was struck by the lack of comment on the macronutrient content of the diet provided throughout. It was as if calories were all that mattered.

The daily diet was virtually entirely carbohydrate based, with a stark absence of protein and fat. That would largely explain the muscle loss and physical fatigue. It would also explain the mental health symptoms: the brain cannot function properly without fat and protein. Plus, the inevitable swings between high and low blood sugar would certainly have been a major factor in both mental and physical symptoms. These men must have been severely malnourished, as well as everything else.

---

This experiment should be viewed as a warning not only against calorie restriction, but against fat and protein restriction.

In hindsight, it had disaster written all over it. But just as disastrous is the absence of lessons learned from the experience by those experts whose job it to provide dietary guidance to people aiming to lose weight.

In the US, the Academy of Nutrition and Dietetics recommends as a general guidance that men wishing to lose weight should consume 1,500-1,800 calories a day, and women 1,200 – 1,500 calories.

Meanwhile obesity rates continue to rise exponentially.

So the next time you are told that all you have to do to lose weight is eat less and move more, remember those brave volunteers who already tried that, so you don’t have to.

If you enjoyed reading about the Minnesota experiment, you might also enjoy this. It’s the true story of a morbidly obese man who ate absolutely nothing - seriously - for over a year. He successfully lost weight without losing his mind.

The Curious Case of the Man Who Ate Nothing For Over a Year

It’s not something to be recommended, though. Here’s how to do it in a more measured, healthy and realistic way.

Why “Eat Less, Move More” Doesn’t Work for Weight Loss