strongernow
09-17-2004, 07:26 PM
Cut the string of yo-yo diets
Weight fluctuation may affect health
If you are thinking of going on a diet, you might want to think hard about two strategies:
How to take the weight off.
How to keep it off.
Yo-yo dieting, in which someone repeatedly loses and regains at least 10 pounds, may have a lasting negative impact on the immune system, making it harder to fight everything from colds to infections to cancers.
The findings, from research done at the Fred Hutchinson Cancer Research Center in Seattle, are considered preliminary.
They were drawn from a small sample of 114 overweight, but otherwise healthy sedentary, postmenopausal women who reported on their weight-loss history for the previous 20 years.
Blood tests showed that the "natural killer cell" activity was higher among women in the group who kept their weight fairly stable over the years and didn't yo-yo diet. Natural killer cells, or NK cells for short, are a vital part of the immune system that recognizes and kills tumor cells and other targets.
The findings add to other recent studies of postmenopausal women that cite negative effects of yo-yo dieting.
Last year another small study found that post-menopausal yo-yo dieters were much more likely to have reduced myocardial blood flow to their heart, regardless of their current weight.
Those who gain or lose at least 10 pounds over a yearlong period at least five times over their lifetime may be setting themselves up for heart problems after menopause, researchers at the VA/Ann Arbor Healthcare System and the University of Michigan Health System concluded.
Four years ago, another study found that chronic dieters who lose and regain weight appear to have lower levels of high-density lipoprotein (HDL) — the "good" cholesterol — thus increasing their risk of heart disease.
This study, led by Dr. Noel Bairey Merz of Cedar-Sinai Medical Center in Los Angeles, studied 445 women at four institutions.
Because of their small size and other factors, none of these studies can be called anything but preliminary and intriguing.
"If the results of our cross-sectional study could be confirmed in an ongoing longitudinal study, the public health impact could be substantial for the estimated 50 percent of American women who are currently dieting and recently have attempted to lose weight, often without long-term success," said Dr. Cornelia Ulrich, a molecular and nutritional epidemiologist at the Hutchinson Cancer Research Center.
Girls and women in a quest for thin-as-fashion-model figures are susceptible to using crash diets that often result in the weight going back on when they can no longer maintain rigid eating regimes.
But weight loss by those who are truly overweight benefits them by lowering their blood pressure, reducing their risk of diabetes, protecting their joints and preventing certain cancers, experts agree.
So what should people who need to lose weight do?
Clinical nutritionist Erin Shade, author of the Hutchinson center study, said, "I would encourage people to lose weight gradually and to think about changes in lifestyle. It will put less stress on their immune system and they will be more likely to keep the weight off."
"Someone on a crash diet probably is not getting enough" nutrients of various kinds and that may be why their immune functions may suffer damage, Shade said.
A panel of experts of the National Institutes of Health concluded nine years ago after looking at more than 40 studies that there was no evidence that weight cycling, or yo-yo dieting, was harmful.
Such panels "are looking for compelling evidence," Shade said. Most of the previous studies were from the 1980s.
Shade and other researchers believe that more study of weight cycling is needed, especially since obesity is increasing worldwide, prompting many to try crash diets.
Weight fluctuation may affect health
If you are thinking of going on a diet, you might want to think hard about two strategies:
How to take the weight off.
How to keep it off.
Yo-yo dieting, in which someone repeatedly loses and regains at least 10 pounds, may have a lasting negative impact on the immune system, making it harder to fight everything from colds to infections to cancers.
The findings, from research done at the Fred Hutchinson Cancer Research Center in Seattle, are considered preliminary.
They were drawn from a small sample of 114 overweight, but otherwise healthy sedentary, postmenopausal women who reported on their weight-loss history for the previous 20 years.
Blood tests showed that the "natural killer cell" activity was higher among women in the group who kept their weight fairly stable over the years and didn't yo-yo diet. Natural killer cells, or NK cells for short, are a vital part of the immune system that recognizes and kills tumor cells and other targets.
The findings add to other recent studies of postmenopausal women that cite negative effects of yo-yo dieting.
Last year another small study found that post-menopausal yo-yo dieters were much more likely to have reduced myocardial blood flow to their heart, regardless of their current weight.
Those who gain or lose at least 10 pounds over a yearlong period at least five times over their lifetime may be setting themselves up for heart problems after menopause, researchers at the VA/Ann Arbor Healthcare System and the University of Michigan Health System concluded.
Four years ago, another study found that chronic dieters who lose and regain weight appear to have lower levels of high-density lipoprotein (HDL) — the "good" cholesterol — thus increasing their risk of heart disease.
This study, led by Dr. Noel Bairey Merz of Cedar-Sinai Medical Center in Los Angeles, studied 445 women at four institutions.
Because of their small size and other factors, none of these studies can be called anything but preliminary and intriguing.
"If the results of our cross-sectional study could be confirmed in an ongoing longitudinal study, the public health impact could be substantial for the estimated 50 percent of American women who are currently dieting and recently have attempted to lose weight, often without long-term success," said Dr. Cornelia Ulrich, a molecular and nutritional epidemiologist at the Hutchinson Cancer Research Center.
Girls and women in a quest for thin-as-fashion-model figures are susceptible to using crash diets that often result in the weight going back on when they can no longer maintain rigid eating regimes.
But weight loss by those who are truly overweight benefits them by lowering their blood pressure, reducing their risk of diabetes, protecting their joints and preventing certain cancers, experts agree.
So what should people who need to lose weight do?
Clinical nutritionist Erin Shade, author of the Hutchinson center study, said, "I would encourage people to lose weight gradually and to think about changes in lifestyle. It will put less stress on their immune system and they will be more likely to keep the weight off."
"Someone on a crash diet probably is not getting enough" nutrients of various kinds and that may be why their immune functions may suffer damage, Shade said.
A panel of experts of the National Institutes of Health concluded nine years ago after looking at more than 40 studies that there was no evidence that weight cycling, or yo-yo dieting, was harmful.
Such panels "are looking for compelling evidence," Shade said. Most of the previous studies were from the 1980s.
Shade and other researchers believe that more study of weight cycling is needed, especially since obesity is increasing worldwide, prompting many to try crash diets.