Hormones Linked to Weight Gain After Dieting

The triumph of weight loss after endlessly counting calories and sweating off pounds through vigorous exercise can be short-lived. Dieters have long-known that successful weight loss is hard earned, and many struggle to keep off those unwanted pounds, and eventually lose the battle without ever knowing why. But a group of Australian researchers may have uncovered at least a partial explanation for the failure of many to remain trimmer post-diet though long-term weight maintenance.

Findings of a new study from the University of Melbourne and Australia’s La Trobe University have revealed that for at least a year after dieting, a combination of hormonal changes endlessly signal the body to not only slow down metabolism, but also to increase the appetite.

A dieter’s own biology sets up a treacherous plan for failure to remain trim without a fight, supporting the belief of many experts that dieters who gain back weight have not just given in to old habits. Details of the findings appear in the New England Journal of Medicine.

A number of previous studies have found that when overweight people shed extra pounds, the body forcefully responds with hormonal changes that greatly affect appetite and satiety.

According to the study authors, the body kicks in with “multiple compensatory mechanisms encouraging weight gain.” As an example, loss of body fat decreases the levels of a hormone produced by fat cells, known as leptin. The hormone drop causes the body to signal the brain that energy stores are running low, which leads to a decrease in metabolism and and increase in appetite.

Although the triggers are nature’s way of promoting survival under the right conditions, for those who need to lose weight, the body ends up working against the dieter.

The study authors explain, “These mechanisms would be advantageous for a lean person in an environment where food was scarce, but in an environment in which energy-dense food is abundant and physical activity is largely unnecessary, the high rate of relapse after weight loss is not surprising.” In fact, during their research it was discovered that not only are the hormonal changes very persistent, but could actually even be permanent.

For the analysis, the researchers followed 50 people who were either overweight or obese for a period of 16 months. All of the participants had enrolled in a highly intense, ten-week diet program, during which they consumed only 500 to 550 calories per day for the first eight weeks. A total of 11 of the participants didn’t make it through this phase of the study. They either did not lose the 10 percent of body weight required to continue their participation in the study, or simply dropped out, proving just how hard it is to successfully attain weight loss.