|Why dieters tend to regain weight|
|Friday, 28 October 2011|
As if we needed any reminder that weight loss is hard and maintaining weight loss even harder, a study has found that for at least a year, subjects who shed weight on a low-calorie diet were hungrier than when they started and had higher levels of hormones that tell the body to eat more, conserve energy and store away fuel as fat.
The report, just published in the New England Journal of Medicine, helps explain why roughly four in five dieters wind up gaining back lost pounds within a year or two of losing them — and, sometimes, pack on a few extra pounds for good measure.
It is a close look at the disheartening pattern: In the wake of weight loss, "multiple compensatory mechanisms" spring to life, the study illustrates, and work together to ensure that weight loss is reversed quickly and efficiently.
The researchers, led by Joseph Proietto of the University of Melbourne's Department of Medicine, write that more than one solution to the crisis of obesity will likely be necessary: "a combination of medications" that will have to be safe for long-term use.
The Australian study paints a "very comprehensive" and "really discouraging" picture of the breadth of the body's response to weight loss, said Dr Daniel Bessesen, an endocrinologist and obesity researcher at University of Colorado's Denver Health Medical Center. It captures just how many resources the body musters to ensure that pounds are put back on — a long list of hormones that regulate appetite, feelings of fullness after eating and how calories are used.
With names such as leptin, ghrelin, amylin, cholescystokinin and insulin, the hormones vary widely. Some are secreted from the gut, others by the pancreas or fat cells themselves. Some dial appetite up, others send word to the brain that plenty has been consumed, and still others help regulate how calories are used.
At 52 weeks after subjects had completed their crash diets and were struggling to maintain their loss, that cacophony of hormones was sending a single message, loudly, clearly and after every meal: Eat more.
And subjects were getting that message. When asked, they said they were just as hungry as they had been upon completion of their crash diets and significantly hungrier than they had been before their diets had begun.
"The high rate of relapse after dieting is not surprising," the authors concluded.
Professor Proietto said the study revealed the important roles that hormones play in regulating body weight, making dietary and behavioural change less likely to work in the long-term.
“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.
“The study shows it is the control of hunger following weight loss that needs to be managed. This may be possible with long-term pharmacotherapy or hormone manipulation but these options need to be investigated,” he said.
“Ultimately it would be more effective to focus public health efforts in preventing children from becoming obese.”
Barbara Corkey, an obesity researcher at Boston University, said that although the subjects' rapid regain of weight was no shock, the authors had turned up important evidence on how distinct hormones work individually and collectively to fight weight loss.
The result, she said, could help in devising new drugs and strategies to support dieters who just want to hang on to their losses.
LA Times: Read full article here
Long-Term Persistence of Hormonal Adaptations to Weight Loss