Truth: This erroneous obesity myth is based on one of the first things you'll hear in a college nutrition class: the 3,500-calorie rule. This rule states that if you cut out 3,500 calories from your diet, you’ll lose one pound, and if you eat an extra 3,500 calories (beyond what you burn), you’ll gain one pound. The problem is that the rule is based on short-term experiments in men on very low-calorie-diets. In real life, it just doesn't work that way. You don't keep losing weight at the same rate over time, because, as weight is lost, the energy your body needs changes.
"The one myth [that hurts perhaps people the most is] the 3,500 calorie rule," Krista Casazza, a co-author of the New England Journal of Medicine paper and an assistant professor in the department of nutritional sciences, University of Alabama, told TakePart. "It can, in some instances, make or break a weight loss effort at the individual level...We're told that if you cut your calories by 3,500 you'll lose a pound. But that assumes everything stays exactly the same.” But, she says, the body adapts to any change, including weight loss, making sustained weight loss not such an easy equation.
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