It is common knowledge that dieters often gain weight back soon after losing it, but up until now, the reason remained elusive. Why is it so hard for people to keep the weight off? A recent australian study showed that after a diet in which a person loses 10% or more of their bodyweight, levels of hormones associated with hunger drastically increase in response to the decrease in body fat. The levels of a key hormone, leptin which increases metabolism and reduces hunger, fell in response to dieting. This explains why immediately after a diet, many feel very hungry and gain their weight back. However, in a recent study, even when dieters kept the weight off for a year, leptin levels were still lower than pre-diet levels, their metabolism was slower than pre-diet, and hunger was elevated. Interestingly, when the dieters gained their weight back, their bodies returned to a more metabolically normal state, with normal levels of leptin and other hormones regulating hunger and metabolism. These results suggest that perhaps supplementing key hormones may help dieters to return to a more metabolically normal state after losing weight. One thing is clear: our bodies want to keep us fat.
Reference: Kolata, Gina. "Study Shows Why It's Hard to Keep Off Weight." The New York Times. Web. http://www.nytimes.com/2011/10/27/health/biological-changes-thwart-weight-loss-efforts-study-finds.html?_r=1&ref=health. Oct 26 2011.
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