Is Starvation Mode Real? Here's What The Science Says

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What 36 Starving Men Can Teach Us About Fat Loss

I don’t know many other things in my life that I looked forward to being over more than this experiment. And it wasn’t so much … because of the physical discomfort, but because it made food the most important thing in one’s life … food became the one central and only thing really in one’s life. And life is pretty dull if that’s the only thing.
— Harold Blickenstaff, Study Participant

There’s a lot of misinformation and misunderstanding about what starvation mode is, what it does and how it works.

Most people wrongly believe that starvation mode will cause them to;

  • Stop losing weight

  • Regain weight

  • No longer be in a calorie deficit

The truth is that starvation mode as most people see it is not something you need to worry about.

What follows is a true story.

The Minnesota Starvation Experiment

November 1944, World War II is raging but all is quiet in the hallways of the University of Minnesota Football stadium as 36 young men are shown to their new home for the next year.


They volunteered in response to a poster to be part of an experiment that was to be conducted by Dr. Ancel Keys and his team of scientists (1).

A copy of the poster the men responded to.

A copy of the poster the men responded to.

At the time, the effects of hunger and starvation were rampant in heavily rationed countries and whilst there was anecdotal evidence of its effects there was little to no actual scientific literature.

Keys and his team set out to change this.

Over 200 individuals applied to take part in his study but in the end, only 36 were chosen, they were chosen on the basis of their good physical and mental health as well as their ability to bond with others in difficult circumstances.

The aim of the experiment was to monitor the physical and psychological effects of semi-starvation on the men whilst also examining the most effective way to help individuals recover and rehabilitate after starvation.

Note: If starvation mode as most people see is the correct definition then we would expect to see most if not all participants lose some weight before plateauing or even gaining weight during the study.

Ancel’s study required the men to lose 25% of their body weight and was split into 4 phases.

  1. Three months of eating a normal maintenance diet of 3,200 calories a day

  2. Six months of semi-starvation using a calorie restricted diet of 1,570 calories a day*

  3. Three months of restricted rehabilitation consisting of 2,000 – 3,200 calories a day

  4. Eight weeks of unrestricted rehabilitation where no limits were placed on calories**

*Several participants were kicked out of the study for cheating on their diet.

**Only 12 of the 36 stayed on for the non-compulsory 4th phase. During this period of unrestricted eating, they often consumed 5,000 calories a day with one man eating 11,500 on one day.

During the entirety of the study participants were required to walk 3 miles a day as well as work in the lab for 15 hours week and participate in educational activities for 25 hours a week.

What Did They Find?

They found that prolonged semi-starvation led to emotional distress and depression in most men.

They also noticed that all men lost interest in sex, became obsessed with meals time and frequently got irritated if meals were not served on time.

However, most importantly to this discussion, the researchers found that during phase 2, although there was a marked decline in the subject’s basal metabolic rate all men lost weight and continued to lose weight throughout this period.

In fact, they kept on losing weight until they got all the way down to 5% body fat and could no longer lose any more weight without risking serious health implications (2).

The dramatic weight loss of participants in the study

The dramatic weight loss of participants in the study

Does this mean you should use semi-starvation to lose weight?

Hell No!

You should never do this BUT there are 2 important points we can take from this study:

  1. If you’re in a calorie deficit you will lose weight

  2. Your caloric needs will decrease as you lose weight

What This Means For You

The results of this study are clear.

  • To lose weight you must be in a sustained calorie deficit.

  • However, the longer you’re in a calorie deficit the more your weight loss will slow down

This means if you want to lose fat you first need to be in a calorie deficit;

  • Bodyweight in lbs x 12 = calorie deficit

You then need to work to overcome the decrease in energy expenditure and daily caloric needs which happen as a result of a prolonged calorie deficit.

Fortunately, there are several well-documented strategies to reset your weight loss;

  1. Recalculate your calories

  2. Incorporate regular refeed days

  3. Use a strategic diet break

By following these 2 guidelines you’ll be able to continue losing weight over the long-term.

Perhaps The Most Fascinating Thing...

Almost 60 years after the Minnesota Experiment, 19 of the 36 original participants were still alive and 18 were interviewed in an oral history project conducted from July 2003 through February 2004.

A letter was sent to each participant, inviting him to take part in a tape-recorded, structured interview. After oral consent was obtained, 14 participants were interviewed in their homes or offices, and 4 were interviewed by telephone.

Perhaps most interesting of all is that all things considered…

“the participants agreed that if the clocks were turned back, they would again make the same decision to participate, even after having experienced the physical sacrifice required.”

Takeaway Point

In this incredible story of 36 men who sacrificed a year of their lives and risked their mental and physical health, we can learn a lot about fat loss and ‘starvation mode’.

Through the results of this study, we can see that fat loss is the outcome of a sustained calorie deficit.

However, we also learnt that a prolonged calorie deficit gives rise to changes in the body that reduce daily energy expenditure and a decrease in caloric needs over time.

Therefore, successful weight loss involves the creation of a calorie deficit and the successful negation of the inherent decrease in calorie needs.

This is what 36 men can teach us about fat loss.

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