In the early 1940s, reports started coming out of Europe that a lot of people were going hungry. Some of this was from the expected food disruptions caused by war. But there were other, more unsettling reports of huge numbers of people being held in camps, where they were slowly being worked and starved to death. The US government wanted to know more about how starvation worked and how best to help these civilians recover in the post-war years.
A team of doctors and scientists came up with a plan. For one year they would take a group of volunteers (drawn from a pool of conscientious objectors who owed the Army service) through an experience similar to that of an internment camp. The subjects would see their caloric consumption cut in half, while still being required to do manual labor and 22 miles (35km) of walking a week. After 6 months of starvation, the men would then be taken back up to their normal caloric levels. Each step of the way the subjects were analyzed for both physiological and psychological changes.
In November 1944, 36 subjects arrived at the University of Minnesota to begin their year-long study. This became known as the Minnesota Starvation Experiment. Entire books have been written on this landmark study, but I want to draw out the main points that apply to our lives in the modern world, especially if you’re looking to lose weight.
A group photo of the Minnesota Starvation Experiment participants. Subjects lost about 1/4 of their body weight on a diet that restricted their calories to about half of their daily requirements for 6 months (roughly 1500 calories per day).
The Myth of “Starvation Mode”
In the last decade, a popular counterculture has risen up against dieting by reducing calories. One of the core beliefs of this movement is that when the body consumes less energy than it uses, it enters “starvation mode.” In this supposed starvation mode, your body’s self-defense mechanisms kick in, your metabolism slows, and you stop losing weight, even as calories decrease. In this way, reducing calories can permanently damage your metabolism, making you more likely to gain weight in the future.
The Minnesota Starvation Experiment gives us detailed data about exactly what happens when a body faces caloric restriction for weeks on end. When the body is deprived of calories, it does indeed show reduced metabolic activity. But the majority of this slowdown can be attributed to the loss of physical mass. A body that has lost ¼ of its mass has ¼ less tissue to maintain, and as a result requires less energy to do it.
The second biggest factor in reduced metabolic rate is that the starving men engaged in far less spontaneous physical activity, idling for hours a day in a kind of fugue state.
The body in starvation resists all non-essential activity.
At the deepest point of the starvation, the subjects were showing a metabolic underperformance of 20% under what would be expected for their weight. For example, if it was expected they would burn 100 calories per hour, they would only burn 80. This was after six straight months of the most severe caloric restriction possible without threat of death.
At no point did the subjects stop losing weight. At no point did a switch get flipped where their bodies started using a different metabolic process. The weight loss occurred in predictable curves, and occurred across all subjects regardless of genetic background or body shape.
When the refeeding portion of the experiment began, the subject’s metabolisms picked up as expected, right along with their body weight. Three months later, most of the subjects were back to regular metabolic levels. Some still had reduced metabolism, but no more than 10%. Further studies have shown that after a few more weeks all participants had returned to normal metabolism.
In other words, there was no significant “starvation mode” that the body entered into. If anything, the starvation mode was a reduced willingness to move without a good reason, which is a trait of starvation that we see across the animal kingdom. In evolutionary terms this steady metabolism makes sense. If a body was so easily sabotaged by a single season of low food availability, we wouldn’t have survived for very long through the ups and downs of life in the wild. Entering starvation mode isn’t an issue you need to worry about with a normal diet intervention.
However, the Minnesota Starvation Experiment showed conclusively that an overly restrictive diet DOES have major drawbacks. They’re not the metabolic issues that people are worried about, but the psychological damage that occurs during starvation.
This is Your Brain on Starvation
When calories dropped to half of their daily needs, all of the Minnesota subjects showed immediate and severe changes in mood and behaviour. Where once the men had been social and cheerful, they quickly became apathetic and irritable. They found conversation tedious, and withdrew into themselves, with a favorite pastime being going to watch movies alone.
As the weeks of starvation passed, food became the primary focus of the men’s days. They began exhibiting strange ritualistic behavior at meal times, holding food in their mouths for several minutes, cooing at their meals, arranging the food over and over again, and slowly licking their plates clean.
In between meals, the men would fantasize about food, discuss food, and pore through cookbooks. All other aspects of life fell away and their next meal became the dominant priority of their waking hours.
Subjects began collecting food magazines and cookbooks to gaze at between meals.
When the 12 week period of refeeding began, these psychological issues didn’t go away. Preoccupation with food continued, antisocial behavior remained, and irritability became outright aggression. In the most disturbing moment of the experiment, a subject chopping wood brought the axe down on three of his own fingers in a state identified as “semi-starvation neurosis.”
After 3 months, the worst of these psychological tics had passed, but all the subjects still reported disordered eating. Many had started eating continuously, with some bingeing on food to such a point that they required stomach pumping and hospitalization. The men had difficulty distinguishing between normal healthy hunger and the pain of true starvation. Years later many of the subjects still reported an uneasy relationship with food.
This experience echoes the stories told by nearly everyone who goes through severe caloric restriction, whether by choice or not. Talking with bodybuilders prepping for a competition and MMA fighters cutting to make weight, I’ve heard the same issues come up — low energy, irritability, a preoccupation with food, and an inability to go back to normal eating once the event has passed.
What we can learn from the Minnesota Starvation Experiment
This landmark study and the many that have followed in its footsteps give us some clear takeaways on how to lose weight properly.
- Calories in / Calories out is the law of the land.
In this experiment, the researchers were able to predict the subjects weight loss with great precision, simply by knowing which foods were being eaten and in what quantity. The amount of airtime given to small hormonal or metabolic differences between people is vastly overblown. The amount of calories you eat will be 99% of how much mass you carry. Believe it.
- The body can handle severe caloric restriction, but the mind can’t.
On paper, it seems so simple. You want to lose weight, and if you eat 1000 less Calories than you need a day, you’ll hit your target in just a few weeks. Your body will be able to roll with those punches, but your mental health and quality of life will suffer immensely. You’ll be lethargic, joyless, isolated, and develop disordered eating patterns which can dog you for years to come.
Do you want to finally reach your target weight, but find that you take no pleasure in it because you’ve broken your brain in the process? No way!
- If you want to lose weight, you MUST take it slow.
A caloric deficit of 200 Calories a day is as fast as I’d want anyone to go. Even with that mild number you’ll be feeling your mind drifting towards food more frequently, and might have episodes of irritability along the way.
If you want to sustainably lose body mass give yourself the benefit of time and a plan. As we like to say at Kenzai, you have 365 beautiful days a year to work on the project that is your wellness. It’s about a lot more than mere weight loss. You want to be leaner, stronger, and more mentally fit. The path towards that goal does not pass through severe caloric restriction. It’s a journey of smart portion control, consistent exercise, and intellectual curiosity. That’s how we design our programs at Kenzai, and that’s what will get you the results you want both on and off the scale.
- Don’t make yourself a starvation test subject.
Steer clear of diets that promote intense fasting, cleansing, or detoxing. These are all just fancy ways to package severe caloric restriction. Don’t let the 36 men of the Minnesota Starvation Experiment’s sacrifices go in vain. Learn from them and lose weight correctly.
- Finally, appreciate the beauty of not starving.
The zen teacher Thich Nhat Hanh has a great quote about toothaches.
“When we’re having a toothache, we know that not having a toothache is a wonderful thing. Yet when we don’t have a toothache, we’re still not happy. A non-toothache is very pleasant.”
Are you feeling the gnawing pain of starvation at the moment? No? Isn’t that a wonderful feeling?
Chances are you’ve never had to experience real starvation in your life. Take a breath now and realize how fortunate that is. Not-starving is a state where you can enjoy your life and accomplish your goals, without every other thought being about your next chance at a bite of food. Despite the enormous wealth the world generates each day, there are still pockets on Earth where people are feeling that gnawing, preoccupying hunger. And unlike the men in the Minnesota experiment, they don’t have medical supervision and an end date on the calendar. If you want to do something to help, check out The Hunger Project, one of the top ranked global charities for hunger relief.
In Japan, every meal is commenced with the phrase “Itadakimasu.” This translates to “I am now receiving this gift,” and is an acknowledgement of all the plants, animals, and people that were needed to bring that food to your plate. Keep this spirit as you make your way through the meals of the day. Not-starving is a gift that keeps you mentally and physically balanced year after year.
Patrick Reynolds // Kenzai Founder