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The Science of Why Caloric Restriction Fails

The body responds by increasing hunger and decreasing energy expenditure

Dr. Jason Fung
Better Humans

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The noted scientist Ancel Keys, who would later play a crucial role in shaping current nutritional orthodoxies, sought to study the effects of caloric reduction in the famous Minnesota Starvation Experiment, published in 1950. With World War II raging, many millions of people were on the verge of starvation and this experiment was an attempt to understand the effects on the human body.

One of the first problems was finding volunteers. As an alternative to going to war, conscientious objectors were recruited (I think they weren’t volunteering as much as they were ‘volun-told’). Eventually, 36 such ‘volunteers’ participated in this study.

Ancel Keys estimated that these subjects were eating roughly 3,200 calories per day. They were put onto a ‘semi-starvation’ diet of 1,560 calories per day with foods similar to those available in war-torn Europe at the time — potatoes, turnips, bread, and macaroni. They were then monitored for 20 weeks after the semi-starvation period.

What happened to them? Here, we can divide the effects into physical and psychological effects.

Physical effects

Coldness, incessant hunger, weakness, exhaustion, dizziness, muscle wasting, and hair loss were some of the symptoms. Heart volume shrank by 20%. Heart rate slowed. Body temperature dropped.

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