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A new hormone linked to weight loss
The future of weight loss may involve tricking your brain into thinking you have a smaller stomach.
While actual stomach-shrinking surgery, also known as stomach stapling and gastric bypass, allows very obese patients to lose hundreds of pounds and keep them off, the results are less magical for those who fight to keep their weight down through exercise and dieting.
Why is it that so many dieters inevitably regain lost weight?
New research suggests that it is the body's hormones that may make this "pound rebound" so difficult to overcome. Blame the newly discovered appetite-stimulating hormone ghrelin, say scientists.
The hormone, which is secreted in the stomach, sends "feed me" messages to the brain that fluctuate throughout the day, depending on how full the stomach is. Ghrelin initiates normal mealtime hunger -- rising shortly before meals and dropping soon after.
Why Gastric Bypass Surgery Succeeds
A study in this week's New England Journal of Medicine reports that ghrelin could play a key role in long-term weight regulation.
A team at the Veterans Affairs Puget Sound Healthcare System and the University of Washington compared blood samples of 13 obese subjects, before and after six months on a low-fat, low-calorie diet, with those of five patients who had undergone gastric bypass surgery.
While dieters lost 17 percent of their body weight, their ghrelin levels simultaneously rose by 24 percent. In contrast, gastric bypass patients dropped 36 percent of their body weight yet saw their ghrelin levels plummet 72 percent lower than those in the diet group.
So stomach-reduction patients may have hormones, or rather the lack thereof, on their side.
And unlike ghrelin levels in the diet group, those in the surgery group did not oscillate in relation to meals. In fact, "ghrelin levels not only failed to rise but dropped profoundly," says Dr. David Cummings, the study's lead researcher and endocrinologist at VA Puget Sound Healthcare System and the University of Washington in Seattle.
Cummings explains the reason for the dramatic difference: The objective of gastric bypass surgery is to shrink the stomach to only 5 percent of its original size by rewiring the course of food through the digestive system. The tiny new stomach pouch can hold only two teaspoons of food, which then travels into the very first part of the small intestine.
It is the presence of ingested food and nutrients that activate the ghrelin cells in the stomach. The permanent absence of food in this organ ultimately suppresses ghrelin production.
Why Diet and Exercise Fail
After diet-induced weight loss, researchers observed a rise in blood-ghrelin levels. In addition to increasing food intake, they discovered that the pesky hormone also slows down the body's metabolic rate. Ghrelin, it seems, is on a mission to maintain body weight.
Over the course of evolution, natural selection has developed genes that in times of feast "put meat on the bones," and in times of famine decrease metabolism in an attempt to increase body weight, says Cummings. And although times have changed, it seems our genes have not. Ghrelin appears to be part of the body's built-in defense mechanism to protect against famine and starvation.
This preservation phenomenon could be why "weight loss occurs fast at first but then slows as the body fights vigorously to regain this predetermined set point," says Dr. Michael Meguid, Nutrition editor-in-chief and director of surgical research at the State University of New York's Upstate Medical University in Syracuse, N.Y.
Ghrelin triggers hunger, says Frank Chae, assistant professor surgery and head of obesity surgery at the University of Colorado Health and Sciences Center in Denver. "Hunger is the chief reason for which most dieters quit dieting and regain the excess weight," he says.
The Future of Weight Loss
So are all conventional dieters doomed to failure because of increased ghrelin? Not necessarily, say researchers, who believe the discovery holds great potential for the future of weight loss.
One possibility is the development of a ghrelin "antagonist," a drug that, like gastric bypass surgery, blocks the production of ghrelin. Cummings believes that such a drug could be an attractive alternative to gastric bypass, and perhaps a treatment for those who are even modestly overweight.
But other experts warn that you may want to wait before indulging in that box of doughnuts.
To begin, many obese individuals report that their eating binges are often unrelated to hunger or actual sensations of stomach emptiness. Rather, the motivation is often triggered by an environmental cue such as a TV commercial or an internal cue such as stress, anger or boredom, says Dr. Mark S. Greenberg, neuropsychologist at Harvard Medical School and the Massachusetts Institute of Technology's Clinical Research Center in Cambridge, Mass.
Greenberg therefore believes that "any comprehensive approach to weight loss/control will have to reckon with these 'non-nutritional' episodes of ingestion, and not just up- or down-regulate the hunger/satiety circuits."
And he's not alone in the belief that while drugs may help, they can't do it alone. "Medications have always been the great hope for weight control but their track records have been controversial," says Chae.
"Drugs and pills are never and probably will never be the only answer," agrees Connie Diekman, director of nutrition at Washington University in St. Louis. "Healthy eating and regular physical activity are essential to weight control and disease prevention, making that part of the weight equation a constant."
www.ABCNews.go.com
The future of weight loss may involve tricking your brain into thinking you have a smaller stomach.
While actual stomach-shrinking surgery, also known as stomach stapling and gastric bypass, allows very obese patients to lose hundreds of pounds and keep them off, the results are less magical for those who fight to keep their weight down through exercise and dieting.
Why is it that so many dieters inevitably regain lost weight?
New research suggests that it is the body's hormones that may make this "pound rebound" so difficult to overcome. Blame the newly discovered appetite-stimulating hormone ghrelin, say scientists.
The hormone, which is secreted in the stomach, sends "feed me" messages to the brain that fluctuate throughout the day, depending on how full the stomach is. Ghrelin initiates normal mealtime hunger -- rising shortly before meals and dropping soon after.
Why Gastric Bypass Surgery Succeeds
A study in this week's New England Journal of Medicine reports that ghrelin could play a key role in long-term weight regulation.
A team at the Veterans Affairs Puget Sound Healthcare System and the University of Washington compared blood samples of 13 obese subjects, before and after six months on a low-fat, low-calorie diet, with those of five patients who had undergone gastric bypass surgery.
While dieters lost 17 percent of their body weight, their ghrelin levels simultaneously rose by 24 percent. In contrast, gastric bypass patients dropped 36 percent of their body weight yet saw their ghrelin levels plummet 72 percent lower than those in the diet group.
So stomach-reduction patients may have hormones, or rather the lack thereof, on their side.
And unlike ghrelin levels in the diet group, those in the surgery group did not oscillate in relation to meals. In fact, "ghrelin levels not only failed to rise but dropped profoundly," says Dr. David Cummings, the study's lead researcher and endocrinologist at VA Puget Sound Healthcare System and the University of Washington in Seattle.
Cummings explains the reason for the dramatic difference: The objective of gastric bypass surgery is to shrink the stomach to only 5 percent of its original size by rewiring the course of food through the digestive system. The tiny new stomach pouch can hold only two teaspoons of food, which then travels into the very first part of the small intestine.
It is the presence of ingested food and nutrients that activate the ghrelin cells in the stomach. The permanent absence of food in this organ ultimately suppresses ghrelin production.
Why Diet and Exercise Fail
After diet-induced weight loss, researchers observed a rise in blood-ghrelin levels. In addition to increasing food intake, they discovered that the pesky hormone also slows down the body's metabolic rate. Ghrelin, it seems, is on a mission to maintain body weight.
Over the course of evolution, natural selection has developed genes that in times of feast "put meat on the bones," and in times of famine decrease metabolism in an attempt to increase body weight, says Cummings. And although times have changed, it seems our genes have not. Ghrelin appears to be part of the body's built-in defense mechanism to protect against famine and starvation.
This preservation phenomenon could be why "weight loss occurs fast at first but then slows as the body fights vigorously to regain this predetermined set point," says Dr. Michael Meguid, Nutrition editor-in-chief and director of surgical research at the State University of New York's Upstate Medical University in Syracuse, N.Y.
Ghrelin triggers hunger, says Frank Chae, assistant professor surgery and head of obesity surgery at the University of Colorado Health and Sciences Center in Denver. "Hunger is the chief reason for which most dieters quit dieting and regain the excess weight," he says.
The Future of Weight Loss
So are all conventional dieters doomed to failure because of increased ghrelin? Not necessarily, say researchers, who believe the discovery holds great potential for the future of weight loss.
One possibility is the development of a ghrelin "antagonist," a drug that, like gastric bypass surgery, blocks the production of ghrelin. Cummings believes that such a drug could be an attractive alternative to gastric bypass, and perhaps a treatment for those who are even modestly overweight.
But other experts warn that you may want to wait before indulging in that box of doughnuts.
To begin, many obese individuals report that their eating binges are often unrelated to hunger or actual sensations of stomach emptiness. Rather, the motivation is often triggered by an environmental cue such as a TV commercial or an internal cue such as stress, anger or boredom, says Dr. Mark S. Greenberg, neuropsychologist at Harvard Medical School and the Massachusetts Institute of Technology's Clinical Research Center in Cambridge, Mass.
Greenberg therefore believes that "any comprehensive approach to weight loss/control will have to reckon with these 'non-nutritional' episodes of ingestion, and not just up- or down-regulate the hunger/satiety circuits."
And he's not alone in the belief that while drugs may help, they can't do it alone. "Medications have always been the great hope for weight control but their track records have been controversial," says Chae.
"Drugs and pills are never and probably will never be the only answer," agrees Connie Diekman, director of nutrition at Washington University in St. Louis. "Healthy eating and regular physical activity are essential to weight control and disease prevention, making that part of the weight equation a constant."
www.ABCNews.go.com
