A Surprising Lesson about Caloric Intake from a Classic Study

Our entire training staff read an article published in the Journal of Nutrition that chronicled and provided historical context for the famed “Minnesota Starvation Experiment.”  This study commenced in 1944 toward the end of WWII.  Ancel Keys, a physiologist at the University of Minnesota conducted the most exhaustive study in human history on the topic of human starvation.  The aim of the study was to learn what happens to humans when they are systematically starved.  Equally as important, Keys (and the War Department) wanted to identify a prudent way to re-feed or re-fuel the massive populations of starved POW’s as the war seceded.  The end result was a 1385-page text titled “The Biology of Human Starvation.”

The study’s design was relatively simple.  Keys took 36 volunteers from a pool of 200 (conscientious objectors to the war) and starved them.  The study could be broken down into three steps:

• A 3-month period of “normalizing” body weight.  Subjects either increased or decreased caloric intake until they achieved a “normal” body weight (that is, they couldn’t be over weight or under weight heading into the next portion of the study).
• A 6-month starvation period.  Subjects were systematically starved until they lost 25% of their total body weight.  
• A refueling period in which subjects were restored to normal body weight.

The results of the study were fascinating and at times, horrific.  The subjects lost massive amounts of weight, suffered depression, hysteria, reduced sex drive, and in 2 cases, were hospitalized for hysteria.  And let me repeat… they lost massive amounts of weight during this 6-month period.  Photos from the study depict nothing short of walking skeletons.

Here is the most interesting aspect of the entire study (and the greatest take home message for us today pertaining to fat loss).  When our staff read how many calories each subject consumed, we were almost in disbelief (and everyone I have shared this with has been in disbelief as well)… 1800 calories per day.  This study reveals the almost staggering reality of what a slightly reduced caloric intake can do over time.  Over the last 10 years, I have worked with hundreds of clients who ascertain that they consume 1500 calories per day but they still can’t lose weight.  In reality, if they were actually only consuming 1500 calories per day, not only would they lose weight, they would actually be starving.  They would be so skinny that they could barely function.  In reality, a woman who thinks she is consuming 1500 calories per day is more likely averaging 2500-3000 per day.  This study, one of the most tightly controlled nutrition experiments in human history, illuminates the fundamental concept that if you reduce your caloric intake, you will lose weight… a lot of it.  Additionally, you don’t need to reduce your caloric intake as low as the vast majority of the population would assume.  Also of note was the content of the diet.  The 1800-calorie diet was comprised almost completely of carbohydrate (because this represented the diet’s that POW’s were receiving).  This flies in the face of the popular misnomer that carbohydrates make us fat.  
An interesting side note, the term “K-rations” comes from Ancel Keys.