AsianScientist (Oct. 28, 2011) – Obese people may regain weight after dieting due to hormonal changes that persist for more than a year, a University of Melbourne and Austin Health study published in the New England Journal of Medicine has shown.
Worldwide, there are more than 1.5 billion overweight adults, including 400 million who are obese. In Australia, it is estimated more than 50 percent of women and 60 percent of men are either overweight or obese.
Although restriction of diet often results in initial weight loss, more than 80 percent of obese dieters fail to maintain their reduced weight.
In this study, 50 overweight or obese adults with a BMI of between 27 and 40 and an average weight of 95 kg were enrolled in a ten-week weight loss program using a very low energy diet.
Levels of appetite-regulating hormones such as leptin, ghrelin, gastric inhibitory polypeptide, and insulin were measured at baseline, at the end of the program and one year after initial weight loss.
Results showed that following initial weight loss of about 13 kg, the levels of hormones that influence hunger changed in a way which would be expected to increase appetite.
Changes to hormonal levels were sustained for at least one year, and participants regained around 5 kg during that year.
Professor Joseph Proietto from the University of Melbourne and Austin Health, a senior author on the study, said that the observed hormonal changes gave clues to why people relapse after losing weight.
“Our study has provided clues as to why obese people who have lost weight often relapse. The relapse has a strong physiological basis and is not simply the result of the voluntary resumption of old habits,” he said.
Although health promotion campaigns recommended obese people adopt lifestyle changes such as to be more active, Prof. Proietto said that they were unlikely to lead to reversal of the obesity epidemic, and that prevention was more effective in the long term.
“Ultimately it would be more effective to focus public health efforts in preventing children from becoming obese,” he said. “The study also suggests that hunger following weight loss needs to be addressed. This may be possible with long-term pharmacotherapy or hormone manipulation but these options need to be investigated.”
The article can be found at: Sumithran P et al. (2011) Long-Term Persistence of Hormonal Adaptations to Weight Loss.
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Source: University of Melbourne.
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