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Jan 9, 2012

Hormones Contribute to Weight Gain After Calorie-Restriction Diet

Across the world today, more than 1.5 billion adults are overweight and 400 million are obese.  More than 50 percent of women and 60 percent of men in Australia are estimated to be overweight or obese.  In one Australian study looking at weight loss after dieting, it was reported that over 80 percent of dieters who are obese fail at keeping their weight off permanently.  While they may make initial progress in losing weight through dieting, it appears that hormonal processes cause the weight to come back.  

In a small scale study of 50 overweight or obese adults, participants were enrolled in a 10-week weight loss program based on a calorie-restriction diet.  All participants had a body mass index (BMI) between 27 and 40, and an average weight of 209 pounds (95 kg).  Circulating hormones, including leptin, ghrelin, peptide YY, gastric inhibitory polypeptide, glucagon-like peptide 1, amylin, pancreatic polypeptide, cholecystokinin, and insulin, were measured at baseline (prior to weight loss), at 10 weeks (after completion of program), and at 62 weeks.  Participants were also asked to give subjective appetite ratings.      

With initial weight loss of approximately 30 pounds (13 kg), results of the study indicated that hormone levels tended to change in such a way following the initial weight loss that appetite was expected to increase.  These hormone levels were found to remain steady for a minimum of one year, and participants tended to regain about 11 pounds (5 kg) over the one-year period.  Subjective ratings of hunger also remained elevated.    

This study emphasizes the important role that hormones can play in regulation of body weight.  Professor Joseph Proietto from the University of Melbourne and Austin Health concluded, "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." 

Although hormones are known for playing a major role in regulation of body weight, it seems important to point out here that this particular study incorporated significant calorie restriction as part of the weight loss program.  Not all methods of dieting for weight loss are considered equal, therefore, it should not be assumed that all diets will provide the same results.      

The study above was published in the New England Journal of Medicine.  

Shana McQueen, N.D.