The Minnesota Starvation Experiment
I’ve said it before and I will keep saying it – weight is not a simple balance of calories-in and calories-out. Overweight and obesity are complex, multifactorial diseases of hormone dysregulation, energy utilization and storage, genetic and epigenetic influences and a whole host of complex processes – very few processes that have anything to do with calories. Granted, severe calorie restriction for a prolonged period of time will result in weight loss in everyone that experiences it. However, the loss is not linear nor is it identical for each person that undergoes it. And it can have severe consequences.
Scientists actually studied this in the 1940’s (before medical studies were tightly controlled!) They paid a group of men to undergo a controlled starvation period and then observed what happened to these men – both physically and mentally. This later became known as The Minnesota Starvation Experiment. Here’s a cliff notes version of the study:
The researchers recruited 36 healthy men (all with normal body weight) into participating in a prolonged experiment. The research protocol called for the men to lose 25 percent of their normal body weight. The men spent the first three months of the study eating a normal diet of approximately 3,200 calories a day, followed by six months of semi-starvation at 1,570 calories a day. After the starvation period, they went through a restricted rehabilitation period of three months, during which times their calories were slowly increased, and finally an eight-week unrestricted rehabilitation period during which there were no limits on caloric intake (but what they ate was still recorded in detail).
The men were required to work 15 hours per week in the lab, walk or run 22 miles per week and participate in a variety of educational activities. Throughout the experiment, the researchers measured the physiological and psychological changes brought on by near starvation.
As expected, the participants all lost weight. Ironically, the fact that the weight loss was irregular and the calorie goals of each man had to be repeatedly adjusted seems to punch some pretty big holes in the calorie balance hypothesis. However, the most important take-away from the experiment is that the impact of their weight loss and limited food availability was profound.
The subjects all experienced the following:
Food Preoccupation: For the volunteers, the days revolved around meal times. The men dreamed about food, they fantasized about high calorie/high fat food items they couldn’t access. They spent much of their time talking about food. They became agitated if the timing of the meal schedule was changed or if a meal was delayed. Some of the men reported experiencing pleasure by watching others eat or smelling food.
Abnormal Eating Behaviors: Some men extended their eating experiences as long as they could, not wanting the pleasurable experience to end. Keep in mind, the food served was actually tasteless, cafeteria food. With unlimited access to coffee and chewing gum between meals, many of the men chewed and drank constantly; up to 40 sticks of gum and ≥ 80 ounces of coffee each day. When the men got unexpected access to food, they would binge eat, consuming thousands of calories in a seating.
Mood Changes: The mood and energy of the group quickly shifted. Where the men had once been a lively crew, discussing and debating politics & current events, they quickly became single-mindedly focused on food. They were irritable and anxious. Most of the subjects experienced periods of severe emotional distress and depression. Sexual interest was drastically reduced, and the men showed signs of social withdrawal and isolation. All participants reported a decline in concentration, comprehension and judgment capabilities.
Distorted Self Image: In spite of their significant weight loss and skeletal appearance, most of the men did not report themselves as underweight. They actually described others in comparison as “fat.” Some of the men became preoccupied with their abdominal area, expressing discomfort with bloating, constipation, and gas.
Rebound Eating: After six months of starvation and the loss of approximately 25% of their body weight, the men were observed through the re-feeding process. During the restoration phase of the experiment, the men had extraordinary calorie needs – requiring over 4000 calories per day in order to restore their weight. A subset of the men were allowed to re-feed without a controlled protocol and these men engaged in extreme overeating.
Physical Changes: In addition to significant muscle-wasting and fatigue, most of the men developed anemia, neurological deficits, and lower extremity edema (swollen ankles). There were marked declines in physiological processes reflected in reduced body temperature, respiration and heart rate. Thankfully, as the men restored their nutrition and weight, their physical symptoms and irregular behaviors appeared to normalize. There did not appear to be any enduring health problems.
You are probably wondering: why does this have to do with me and my weight?
So many people I meet are still hell-bent on the idea that all we have to do to lose weight is to decrease the amount of food we eat (calories-in) and increase our energy expenditure (calories-out). When we fail to achieve weight loss by doing that, we judge ourselves and others as “failures”. We talk about our lack of willpower and discipline.
Calorie restriction does work for a very small subset of the population – and how we all wish we could be in that subset!! However, for the rest of us, it sometimes works once (usually when we are really young and haven’t had excess weight very long) and then it stops working. After that, we get on the weight roller coaster, continually dropping or gaining weight – all the while berating ourselves for being unable to have the willpower to comply with our simple calorie-restricted plan.
Maybe it’s time to stop thinking in terms of calories
There are several things to take away from The Minnesota Starvation Experiment:
- The restriction of calories leads to a heightened interest in food and eating. It’s perfectly natural during calorie deprivation to become overwhelmingly preoccupied with food.
- Prolonged restriction of food negatively impacts mood. Food restriction leads to an increase in anxiety symptoms and obsessive thinking.
- Once under-eating is ended, it is perfectly natural for the body to overeat. There is a biological pull to regain weight.
Put these things into an environment with unlimited access to food and it’s a recipe for disaster!
One of the lectures that I give to medical professionals is titled, “Rethinking the First Law of Thermodynamics” and the framework of the lecture pokes holes in the idea that dysregulation of calories-in, calories-out is the explanation for weight gain and weight loss. We have so much science to disprove the calorie balance hypothesis. We need to change the way we think about weight gain and excess weight.
However, the idea is so ingrained in most of our brains that thinking outside that box takes some getting used to. I imagine it’s similar to people long-ago having to comprehend that the world isn’t flat. Even though the calorie-balance concept is not grounded in fact, most of us want scientific proof before we change our way of thinking. Which is fine – I’m the same way. I love proof. I love getting into the biochemical processes playing out in the human body. If you are a patient in my office, you know that we talk about hormones and neurotransmitters and all kinds of things that play a role in weight regulation.
The reason that most of us struggle with excess weight has nothing to do with willpower. We are not weak or gluttonous or slothful or lazy. Some of the most brilliant, ambitious, motivated people struggle with excess weight. Telling ourselves that story only serves to knock our self-esteem down notch after notch.
Regulation of body weight is a complex process involving more than calories!
Give that concept some time to settle in your brain and take root. Once you accept it, you can start the process of understanding what does regulate body weight and then learn how to adjust those processes to decrease excess weight or prevent future weight gain. You can use that knowledge to affect your excess weight. It might not be easy – treating disease is rarely a process filled with unicorns and rainbows – but done correctly and scientifically – it can be successful.
In my office, we never talk about calories. Some of my patients initially find this to be odd, but they typically get over it (or they stop talking to me about it because they know I will flap my hands and direct the conversation elsewhere!) If you aren’t a patient in my office, that’s fine – but next time you decide to put your efforts into dealing with excess weight, be warned. If the program begins by telling you how many calories per day you are going to eat and how many you are going to burn off at the gym, step back and decide if you want to spin your wheels doing the same old thing again. Your body is not a simple math problem. Weight regulation and dysregulation are not problems of addition and subtraction.
Your body is a beautiful machine that constantly adjusts to variations in the environment. The body adjusts to temperature changes by shivering or sweating without conscious thought. It adjusts to changes in light by dilating or constricting its pupils without conscious thought. It adjusts to varying levels of oxygen demands by adjusting its respiratory rate and tidal volume without conscious thought. If it can do all of these things, of course it can adjust its metabolism and behaviors to respond to a decrease in energy intake. Trying to hack those biological processes in an environment with unlimited access to food (not a controlled experiment like those poor men were subjected to in the 1940’s) is bound to fail.
Isn’t it time to do something designed to help you succeed?
Until next time….
stay healthy, stay grounded and keep practicing social distancing so that the most vulnerable among us stay protected
Courtney Younglove, M.D.