Explaining Post-Diet Weight Gain

The biggest complaint amongst dieters who follow a calorie-restricted diet is that as soon as they stop the diet, they gain back most of the weight lost.

post diet weight gainWithin the first year, as many as 80% of dieters gain back the weight lost while on a diet.

To understand better why this is such a common occurrence amongst dieters, scientists out of the University of Melbourne studied appetite hormones to see if they were altered during the dieting process.

Published in the New England Journal of Medicine, the results of this study showed that these hormones indeed were affected for about a year after a calorie-restricted diet. After dieting, the hormones were supercharged and working over time to regain the weight lost. The effect of these altered hormones is increased hunger and a larger-than-normal appetite.

“Maintaining weight loss may be more difficult than losing weight,” says lead researcher Joseph Proietto, PhD, a professor of medicine at the University of Melbourne’s Heidelberg Repatriation Hospital, in Victoria, Australia. “This may be due to biological changes rather than [a] voluntary return to old habits.”

To test this theory, the scientists placed 50 overweight and obese men and women on a 10-week, calorie-restricted diet and then tested their hormone levels over a one-year period.

These blood tests showed that appetite hormones leptin, ghrelin and insulin were altered as a result of weight loss. Subjects also noted an increase in hunger throughout the morning, even after eating breakfast.

Even though the average weight lost was 30 pounds over the 10 weeks, the dieters gained back about 12 pounds over the course of the year. This was in spite of eating a well-balanced diet and exercising on a regular basis. The dieters again noted an increase in hunger pangs and blood tests showed that hormone levels were still unstable.

While these results may shock a few people, the scientists explain that this is a typical response of the body and one that has been hard-wired into our genetics as a survival technique.

“Multiple mechanisms have been developed over eons of evolution to get you to regain weight once you lose it, to tell your brain you’re hungry and to ensure that you don’t stop eating. If you don’t have those drives, you wouldn’t be alive.

Now that we live in a world where calories are so easily consumed and physical exercise—the best way to burn off those calories—is largely unnecessary for day-to-day survival, these biological drives are backfiring and contributing to obesity.” – Dr Charles Burant, Director of the University of Michigan Nutrition Obesity Research Center.

It’s not all a total loss though. Despite these increases in hunger pangs and cravings, dieters can still be successful if they arm themselves with a strong willpower and persevere to resist these cravings.

“That’s not to say that weight regain is inevitable, or that these drives can’t be overcome through willpower. Although the hormone changes noted in the study are very real physical effects, personality and psychological factors may play a role in an individual’s ability to manage chronic hunger. This may explain why some people maintain weight loss for longer than others,” he says. “Maintenance of weight loss requires continued vigilance and conscious effort to resist hunger.” – Joseph Proietto, PhD, University of Melbourne.

Researchers are using this information to develop new ways to help restore hormonal levels after dieting.

Columbia University has used leptin with great success in helping dieters to keep the weight they lost off.

“When diabetics don’t have enough insulin in their bodies, we give them back insulin in order to maintain their blood glucose,” Dr. Burant says. Researchers should be finding a way to do the same for people who have lost weight, he adds, “whether it’s with a drug, a dietary supplement, or certain nutrients—something that will stimulate the release of these hormones.”

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