In 1944, Dr. Ancel Keys conducted The Minnesota Starvation Experiment, the most complete experiment of starvation ever done.
36 young healthy men were selected. For the first three months, they got a standard diet of 3200 calories per day. Over the next six months, calories were restricted to 1570. However, calories were adjusted to reach a target weight loss of 24 percent, around 2.5 pounds (1.1 kilograms) per week. Some men were given less than 1000 calories per day.
They also walked 22 miles per week as exercise.
With such calorie restriction, the men experienced profound physical and psychological changes
- Cold sensation, even on a sunny summer day
- Strength dropped 21 percent
- Heart rate slowed considerably
- Body temperature dropped to an average of 95.8 F
- Physical endurance dropped by half
- Blood pressure dropped
- The men become extremely tired and dizzy
- They lost hair
Psychologically they were devastated, showing a lack of interest in everything except for food.
Some man hoarded cookbooks and utensils. They were constantly hungry and thinking about food, unable to concentrate or dedicate to any mental task.
What was happening?
The men were eating and burning around 3000 calories a day. Then, suddenly, calories were reduced to 1500 per day, less in some cases. All body functions that needed energy experienced an immediate 30 to 40 percent reduction.
Body temperature dropped to an average of 95.8 F: Calories are needed to heat the body, so fewer calories lowered the body temperature. e
Heart rate slowed considerably: Calories are needed for the heart to pump blood. Less calories available means a slower heart rate.
Physical endurance dropped by half: Calories are needing to move the body. With fewer calories available movement was reduced, resulting in weakness during physical activity.
Unable to concentrate or dedicate to any mental task: Our brains needs calories to function. Fewer calories were available so cognition was reduced.
Hair loss: Calories are needed to grow hair. Less calories meant that lost hair was not being replaced
This is the way our body reacts to less available energy. Energy and air are critical for our body to function, and without either of them we will die.
If we reduce calorie intake our body adapts to the available energy, because if we continue to use the same amount as before we would soon would burn our stored energy (fat) than protein stores (muscle), and then we would die.
If we consume 1500 calories per day, the body adapts to burn only 1500 (or a little less for a safe margin), so we achieve a balance and we don’t need to use our stored energy (fat).
Our body gets into economy mode and uses less energy for each function, reducing the energy output.
You feel lousy, cold, and tired but you survive; that’s the most important thing.
The men in the Minnesota Starvation Experiment should have lost 78 pounds (35 kilograms), but they only lost 37 pounds (16.8 kilograms). As the body adapts to the available calorie intake, the only way to lose more weight was with a more severe calorie restriction.
What happened after?
Once calorie intake was restored to normal values, they regained weight quickly and, in only 12 weeks, their weight was higher than prior to the experiment.
Reduced muscle mass and a slower metabolism meant that the extra calories they were now consuming were more readily converted to fat. Also, as a preventative measure, their recently-starved bodies were primed for energy storage and they did so very effectively.
How Calorie Reduction Works?
Let’s say a man or a woman normally eats 2000 calorie per day. Following their doctor’s orders, they adopt a low-fat, portion-controlled, calorie-restricted diet, reducing the daily calorie intake to 1500 calories, 500 fewer calories than before.
Their body starts to adapt, and the total used energy also drops to 1500 calories. First symptoms: they feel lousy, cold, tired, hungry, irritable, and depressed, but they continue the sacrifices to achieve their weight loss goals.
In the beginning weight loss is fast, but as their body adapts to the calorie restriction, calorie expenditure decreases to match the 1500 calories per day and bodyweight plateaus. They continue to make the necessary sacrifices, following the diet as prescribed, but one year later things haven’t improved. Bodyweight starts to slowly increase, even though they continue to follow the diet.
Tired of feeling so lousy the diet is abandoned and our dieter goes back to eating 2000 calories per day. Since their metabolism has slowed to output 1500 calories per day, all the extra calories will be stored as fat, so her weight quickly increases.
Does this scenario sound familiar?
Accused of lacking willpower, our dieter feels like a failure after so many sacrifices.
The truth is that it’s not really failure. What happened is the expected, natural outcome during severe calorie restriction. Calorie restriction doesn’t work in the long term for weight loss.
Imagine that you’re running a coal-fired power plant. Every day to generate energy for the city you receive and burn 2000 tons of coal. You also have a warehouse to store some coal, just in case you need it.
One day, you only get 1500 tons. Should you continue to burn 2000 tons of coal every day? If we did, we would quickly run out of energy and the city would go into total shut down, and we certainly get fired for doing a lousy job.
nA better choice would be to only burn 1500 tons, or maybe a little less to keep a safe margin. Probably some lights would go off but there wouldn’t be a massive blackout, and we would keep our job. As long as we continue to get only 1500 tons of coal we continue to burn only 1500 tons.
Less Calories Less Energy Used
The assumption of fewer calories produces more weight loss is simply not true. The Minnesota Starvation Experiment and other experiments have shown how our bodies adapt and find a balance between calories in and calories out.
You lose weight with calorie restriction in the first few months, but as soon as you finish the diet you will regain all the weight you have lost. In the process, you feel tired, lousy and depressed.
The Weight Loss Fallacy: Eating Less Move More
Dietician, Governments, and Doctors, have been screaming “Eat Less, Move More” as the way to lose weight. But it’s simply not true; it doesn’t work like that.
Losing weight triggers two important responses:
-Reduced total energy expenditure
-Hormonal signals amplify the efforts to acquire more food
Our body adapts to the available energy input and it uses hormones to amplify hunger signals. That’s why the subjects of the Minnesota experiment became so obsessed with food that they started to build kitchen-related tools and all their thoughts were how to get food.
The same thing happens when we are full after eating; our body silences our hunger hormones.
The Sustainable Solution for Weight Loss
There is not a single solution that will work for all of us. Instead, we must find our own solution. The one that works for us.
In my recent article, I explain why diets don’t work and all diets are doomed to fail. You can find it here.
There are proven steps that will help you to lose weight or avoid weight gain. Examples include things like avoiding high sugar beverages, processed or junk food, taking daily walks, skipping breakfast, eating low-carb meals, reducing alcohol consumption, and ditching refined sugar from your diet.
In our newsletter, I share these and other tips about what you can do to lose weight and improve your well-being. There’s no magic formula, but there are steps and strategies that work instead. It’s a journey we all share but we all have our own path to follow.
I’ve recently shared how I’ve lost weight and have been able to keep my exact same weight without restricting my food choices or reducing my calories. Again, this has been working for me for more than one year, but maybe is not something sustainable for you. Learning and experimenting is always the best way. You can find my article here.
I’m here to help you to find the direction for your next step.
Subscribe to our Newsletter and receive one email every Sunday with weight loss tips and tricks to boost your well-being. It’s free and you can unsubscribe anytime you want.
The Obesity Codebook, available at Amazon.com.