The first time I read about the Minnesota Starvation Experiment I was amazed to see how many similarities these participants experienced regarding eating disorders. This experiment is one of the best examples to show us what happens when we restrict foods and how our body reacts to starvation. In this post, I want to show you how the eating disorder develops with dieting and restricting.
During the World War II many people didn’t die because if the bombs and bullets, but because of starvation. In Minneapolis, Minnesota, Dr. Ancel Keys wanted to help those people and conducted an experiment. He wanted to know the physiology of starvation. How and what is the best way to recover from starvation. Knowing the best rehabilitation methods could ensure the health of the population and thereby help democracy grow in Europe after the war.
The design of the study was simple: to starve some subjects and then to refeed them. To achieve this in a controlled, scientific fashion, Keys envisioned a year-long study divided into three parts: an initial three-month control period during which the food intake of the participants would be standardized, followed by six months of starvation, and then three months of rehabilitation.
Keys selected 36 physically and mentally strong men from over 400 volunteers.
For the next twelve weeks — the control period of the experiment — Keys standardized their diet, allowing them 3200 calories a day, while simultaneously putting them through a battery of tests to gather data on variables such as their heart size, blood volume, hearing, vision, fitness, body fat and even sperm count. He also ordered the men to maintain an active lifestyle, working jobs in the lab and walking a minimum of 22 miles a week.
After the first twelve week period, Keys cut the calories from 3200 to 1570 a day. This was the start of a starvation phase of the experiment and it lasted for six months. In today’s society, I think it is very common to suggest somebody to lose weight at 1570 calories a day. Some may say that it is an even healthy number to lose weight. And of course, the number of calories for women would be even lower.
“A patient may choose a diet of 1,000 to 1,200 kcal/day for women and 1,200 to 1,500 kcal/day for men … Experience reveals that lost weight usually will be regained unless a weight maintenance program consisting of dietary therapy, physical activity, and behavior therapy is continued indefinitely. After 6 months of weight loss treatment, efforts to maintain weight loss should be put in place. If more weight loss is needed, another attempt at weight reduction can be made. This will require further adjustment of the diet and physical activity prescriptions.” (1) – The National Institutes of Health
So what the above quote basically says is that you need to reduce your calories to the same level as in the Minnesota Starvation Experiment and if you cannot continue doing it you will regain the lost weight. So starve indefinitely or it won’t work! Great! This is extremely disturbing for me because of the results Keys got while keeping the men at those low number of calories as I soon explain. And keep in mind that this is not even a full starvation, it is a semi-starvation.
And some may argue that it is not as same as with overweight people. Overweight people have more fat to lose, right?
Eating less does not create the need to burn body fat. Instead, it creates the need for the body to slow down. In the absence of adequate energy, our body also uses catabolism (destruction of cells throughout your body) to survive. In the Journal of the American Medical Association, George L. Thorpe, MD, a physician within the American Association itself, wrote that eating less makes us lose weight, not “by selective reduction of adiposis [body fat], but wasting of all body tissues…therefore, any success obtained must be maintained by chronic undernourishment.” (2) It is not practical or healthy to keep ourselves “chronically under-nourished,” so we don’t. Instead, we yo-yo diet. And that is why eating less is not an effective long-term fat loss approach.
When you under-eat, starve yourself, or diet, your body will literally start to eat itself to get energy. It will catabolize your organs, bones, and other body tissues to survive. It will not only take energy from your fat stores, like dieters think but from your entire body. That’s why diets never work and will never result in health. Even if you’re overweight, your body needs enough food to lose weight, to get back to your healthy set-point weight. I know that might sound crazy to you if you’re used to dieting, but that’s how it works. You cannot deprive your body of getting adequate energy and expect your body to do more work – even weight loss requires energy so it can happen healthfully. Yes, you can force your body to lose weight by eating less, but it won’t be sustainable!
But let’s get back to the Minnesota study…So this significant reduction of calories had a very fast effect on men’s health. They saw a remarkable decline in strength and energy. Keys marked a 21 % reduction in their strength measured with a back lift dynamometer. The men also complained that they felt cold and tired. They lost complete interest in subjects that used to interest them like politics and world events. Even sex and romance lost their appeal. Instead, they suddenly became so interested in food.
Some men started to read cookbooks and obsessively stare food pictures and started to collect recipes. This is a very common thing that happens when people start to diet – suddenly food becomes their first priority.
When you restrict something you seem to want it even more. By restricting you actually give it more attention. Eating is very intuitive part of our lives and people without eating disorders just eat as a part of their natural instincts. But people who diet or restrict foods have constant obsessions around it. What to eat, how much, when? If I eat this for breakfast, then what will I have for lunch? How do I prepare it? How many calories does it have? How much fat? Is it healthy, „clean“, pure? Do I need to burn it off later?
I have definitely been there. Constant thoughts about foods are inevitable when you restrict and deprive yourself. The more you try to control your food, the more it starts to control you! And it’s very interesting that some men without any interest in food before the experiment actually became professional chefs after the experiment!
„Meal times became the high point of their day. They grew irritable if they weren’t served their food exactly on time, or if they had to wait too long in line. Although the food was quite bland, to the men it tasted delicious. They lingered over the food, savoring every bite. Often they “souped” their meals — mixing everything with water to make it seem as if there was more.“ (3)
All men were very committed when they had begun the experiment and they knew it was all for a good cause – to help the starving people around the world – but cheating became a huge problem in this experiment.
„The stress proved too much for one of the men, twenty-four-year-old Franklin Watkins. He began having vivid, disturbing dreams of cannibalism in which he was eating the flesh of an old man. On trips into town (before the buddy system had been implemented), he cheated extravagantly, downing milkshakes and sundaes. Finally, Keys confronted him, and Watkins broke down sobbing. Then he grew angry and threatened to kill Keys and take his own life. Keys immediately dismissed Watkins from the experiment and sent him to the psychiatric ward of the university hospital. There, after a few days on a normal diet, Watkins appeared entirely normal again, so the hospital released him. Watkins’ breakdown occurred just a few weeks into the starvation phase of the experiment.“ (3)
As you can see, even though we know that the weight loss can have a good reason (to improve one’s health, for example), but if it comes to dieting, the actual appetite and hunger cues can go out of control and our physical and mental health suffers badly. Eating more after dieting is a natural instinct and it is very hard to force ourselves eat less. It is not about having no self-control or willpower. No wonder 95% of all diets inevitably fail and 99.5% of dieters gain all the weight back after only five years. (4)
Keys also found that the participants heart rate fell significantly. From 55 beats per minute to 35. This was their metabolism slowing down and it was a sign of their body trying to conserve calories. They also didn’t have regular bowel movements and reported just having one per week. Their blood volume dropped ten percent, and their hearts shrank in size. The men developed edema (water retention). Their ankles, knees, and faces swelled — an odd physical symptom considering their otherwise skeletal appearance.
In eating disorders it is very common to retain water and if you start to recover you can have a significant amount of water retention on your body. This is a sign of your body trying to protect you and heal. It is normal to gain 10-15 pounds in a matter of days in eating disorder recovery.
There was also a decrease in basal metabolic rate (BMR). BMR is the amount of energy (calories) the body requires at rest (i.e. no physical activity) in order to carry out normal physiological processes. It accounts for about two-thirds of the body’s total energy needs, with the remainder being used during physical activity. At the end of semi-starvation, the men’s BMRs had dropped by about 40% below normal. This drop, as well as other physical changes, reflects the body’s extraordinary ability to adapt to low caloric intake by reducing its need for energy. One volunteer described that it was as if his “body flame [were] burning as low as possible to conserve precious fuel and still maintain life process” (Keys et al., 1950, p. 852). This is also a sign of metabolic damage or metabolic adaptation in response to a lack of food, or scientifically known as the adaptive thermogenesis (5) some [misinformed] people say does not exist…
Other effects included dizziness, muscle soreness, reduced coordination, and ringing in their ears. But the creepiest change, which occurred in all of the men, was a whitening of their eyeballs as the blood vessels in their eyes shrank. The skin of some of the men developed a coarse, rough appearance, as a result of the hardening of their hair follicles. From the men’s point of view, the most uncomfortable change was the lack of body fat. It became difficult for them to sit down for long periods of time because their bones would grind against the seats.
If you are interested to know about all the starvation symptoms that come through calorie restriction/dieting and how you can actually develop ALL eating disorder symptoms (mental and physical) then please see my video HERE.
Another interesting thing that happened to these men during the semi-starvation period was that even though they were extremely skinny, even skeletal, they didn’t see themselves as being too skinny. Rather they saw that everybody else were just too fat compared to them (body dysmorphia). This is also a very common mindset in eating disorders. The body image and idea of a healthy weight becomes distorted.
The refeeding period
After six months the refeeding period started. Keys divided men into four groups, which received 400, 800, 1200 or 1600 more calories than they had in starvation. He did this to observe the optimum amount of calories for them. But for the men in lowest calorie groups still saw almost no improvement, they still felt hungry all the time and had no signs of recovery. Even after providing them with extra vitamin and protein supplements they didn’t improve, they just needed more calories! He eventually concluded that in order to recover from starvation, a person needs around 4000 calories a day to rebuild their strength.
During rehabilitation, metabolism again speeded up, with those consuming the greatest number of calories experiencing the largest rise in BMR. The group of volunteers who received a relatively small increment in calories during rehabilitation (400 calories more than during semi-starvation) had no rise in BMR for the first three weeks. But for those who consumed larger amounts of food caused a sharp increase in the energy burned through metabolic processes. This is why responding to your full hunger in recovery is important. Your body’s recovery speeds up. You can watch my video about the Health Benefits of Extreme Hunger.
The changes in body fat and muscle in relation to overall body weight during semi-starvation and rehabilitation are of considerable interest. While weight declined about 25%, the percentage of body fat fell almost 70%, and muscle decreased about 40%. Upon refeeding, a greater proportion of the “new weight” was fat; in the eighth month of rehabilitation, the volunteers were at about 100% of their original body weight, but had approximately 140% of their original body fat!
This is how by dieting you will increase your body fat levels over time. It’s our bodies way to protect us from future deprivation. Your body does not know you just want to lose weight to look good but indicates that you are facing a period of starvation and therefore slows down its functions and produces an extra amount of fat in case of next famine period.
„The last meal of the study was served on October 20, 1945. The men were subsequently free to depart and eat as they pleased. However, 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.“ (3)
This last example is so true in eating disorder recovery and I think the most important one! You need to eat unrestrictively and as much as you want. In recovery, this kind of insatiable appetite is known as extreme hunger. Read more HERE.
How did the men feel about their weight gain during rehabilitation? Those subjects who gained the most weight became concerned about their increased sluggishness, general flabbiness, and the tendency of fat to accumulate in the abdomen and buttocks.
These complaints are similar to those of many bulimic and anorexic patients as they gain weight. Besides their typical fear of weight gain, they often report “feeling fat” and are worried about acquiring distended stomachs. During the rehabilitation period some men of this experiment did gain more weight back than they had before, but in time, they lost all the excess weight because they did not restrict again. They gained back their original weight plus about 10%; then, over the next 6 months, their weight gradually declined. By the end of the follow-up period, they were approaching their pre-experiment weight and fat levels. This is how the body weight and fat levels balance out over time by itself.
Keys report highlighted the degree to which what we eat can alter both the mind and the body. However, he also drew an optimistic lesson from the experiment. His data revealed that starvation didn’t appear to have any significant, long-term negative impacts on health. The human body had evidently been designed by evolution to withstand long periods without food.
Almost sixty years later, in 2003, 19 of the original 36 volunteers remained alive. Of these survivors, 18 were interviewed as part of an oral history project about the experiment. They admitted that there had been some lingering after-effects of the experiment. For instance, for many years, they were haunted by a fear that food might be taken away from them again. But overall, they uniformly praised the experience as one of the most important events in their lives. And they insisted that if they were young men again, they would do it again.
In conclusion, I want to stress that the effects of restriction and deprivation to our body is indeed significant and dangerous. One of the most important fact to realize about eating disorders is that prolonged dietary restriction can lead to serious physical and psychological complications. By restriction and deprivation of food, you will create all the eating disorder symptoms. This is just the effect of starvation – it will affect our physical and mental health. Our body slowly starts to shut down even in semi-starvation (as we saw here – 1570 calories a day). And shockingly that’s a number of calories most „diet experts“ recommend as a „healthy amount to lose weight“.
If we restrict we start to have uncontrollable food obsessions, binge eating and other abnormal eating behaviors we see in people with various eating disorders. Also, we develop all the common mental eating disorder symptoms because a malnourished brain is a profoundly malfunctioning organ. Our brain cannot work properly when we are starved.
Yes, starvation may not have negative effects on our body and mind long term if we recover but that can happen only when we do not deprive ourselves and start to eat enough again. So keep in mind – your body can recover and balance out only if you recover and never restrict again.
(1) Clinical Guidelines on the Identification, Evaluation and Treatment of Overweight and Obesity in Adults (1998), Obesity Education Initiative, National Institutes of Health, National Heart, Lung, and Blood Institute, online book, accessed February 5, 2016, LINK HERE.
(2) G. L. Thorpe, “Treating Overweight Patients,” Journal of the American Medical Association, PubMed, as cited in Bailor, A Calorie Myth.
(4) Spinardi, Josie, How to Have Your Cake and Your Skinny Jeans Too: Stop Binge Eating, Overeating and Dieting for Good, Get the Naturally Thin Body You Crave from the Inside Out (2013), Kindle version, accessed February 5, 2016.
Cover image from HERE.