Starvation Mode
"People concerned with starvation mode are concerned that, by lowering their calorie intake drastically, their body's metabolism will lower dramatically to compensate. Starvation mode is a myth. It was popularised due to the Minnesota Starvation Experiment in which subjects were given 50% of their daily calorie intake for months. The result being that they lost weight until they had almost no weight left to lose and their bodies simply could not get the calories anywhere. Concisely put: starvation mode happens when you are, quite literally, wasting away and not when you have a simple caloric deficit. Your body will make up for it with fat stores, which is what they're there for. More on how to stay out of "starvation mode""
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