Atkins results leave dieters and researchers at a loss
People on the low-carbohydrate regimen dropped pounds and improved
cholesterol levels, fueling the debate over the long-term safety of this
weight-loss approach.
By
Susan J. Landers, AMNews staff. Dec. 23/30, 2002.
Additional information
Washington -- Patients at the Duke Diet & Fitness Center in Durham,
N.C., were perhaps hoping for thick steaks when they asked Eric C. Westman,
MD, about changing their low-fat menu. But their desire could also have
been motivated by a surprising finding made by Dr. Westman, an associate
professor of medicine at Duke University Medical Center, and colleagues
that a low-carbohydrate but high-fat diet, long thought by many to be the
nemesis of healthy living, might not be so bad after all.
The researchers compared the low-carbohydrate diet popularized by
cardiologist Robert Atkins, MD, with a low-fat diet, and found that
subjects on the Atkins diet lost more weight and realized greater
improvements in their cholesterol levels than did subjects on a low-fat
diet.
Those findings, presented at a recent meeting of the American Heart
Assn., left many dieters puzzled and some physicians crying foul.
Despite his findings, Dr. Westman is still counseling patients that a
low-fat diet paired with a program of exercise is the best plan for
sensible weight loss and heart health. As for his study, "The results are
encouraging, but not conclusive," he said.
Dr. Westman is currently seeking funding to continue his research and
other studies are also putting the Atkins diet to the test. The National
Institutes of Health has begun a five-year study to determine if the
Atkins weight-loss plan is not only effective but also safe for the heart.
People on a low-carbohydrate diet lost more weight than those on a
low-fat diet.
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For his randomized, controlled study, Dr. Westman enrolled 120 people
and placed half on a low-calorie, low-fat diet. The other half followed
the low-carbohydrate, high-protein diet developed by Dr. Atkins decades
ago. The research, which has been submitted for publication, was funded by
an unrestricted grant from the Atkins Center for Complementary Medicine in
New York City.
Food logs kept by participants showed their fat intake on the Atkins
diet was about 60% of the calories they consumed. This compares to 30% on
low-fat diets. The Atkins group was also provided with several dietary
supplements, including fish oil.
All subjects were advised to exercise although most didn't report much
physical activity, said Dr. Westman. All participants also attended
meetings that were modeled on those held by Weight Watchers, he said. At
the meetings, participants were weighed, filled out forms and discussed
their progress.
How can it be?
At the end of the six months, the researchers found that participants
on the Atkins diet lost an average of 31 pounds compared to an average of
20 pounds for the low-fat dieters.
Those following the Atkins diet also had an 11% increase in
high-density lipoprotein compared to a 1% increase for those on the
low-fat diet.
The fact that those on the Atkins diet lost weight is not that
surprising. It can likely be explained by the tried-and-true method for
losing weight: Eat less.
People on a low-carbohydrate diet improved cholesterol levels more
than those on a low-fat diet.
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There is also a diuretic effect to the diet so some of the weight loss
can be attributed to water loss, said Dr. Westman, who also speculated
that the body might use more energy processing the higher amount of
protein being consumed.
However, given what is known about high fat and cholesterol, "How can
you eat all this fat and yet have your serum fat go down?" Dr. Westman,
and many others, wondered.
For one thing, there is the possibility that the weight loss prompted a
drop in cholesterol, Dr. Westman said.
Another possibility is that the low-dose fish oil supplements, which
were taken by the Atkins dieters, had a pronounced beneficial effect on
cholesterol levels.
But, the long-term safety of the Atkins diet poses another set of
questions that future studies must answer.
"There is clearly short-term danger," said Neal Barnard, MD, president
of the Physicians Committee for Responsible Medicine, a Washington,
D.C.-based, nonprofit organization that promotes preventive medicine,
conducts clinical research studies and promotes alternatives to animal
research. One recently published study showed the Atkins diet produced
changes in the body that increased the likelihood of kidney stones, he
noted.
Increased risks of osteoporosis and colon cancer have been linked to
low-carb diets.
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The Atkins diet can also lead to unacceptably high calcium losses and
an increased risk of osteoporosis, he said. High-meat diets have also been
linked to an increased risk of colon cancer, said Dr. Barnard.
The heart association also took issue with the study, noting that it
was small and, in six months, could not adequately assess the long-term
health risks posed by the Atkins diet.
"People should not change their eating patterns based on one very
small, short-term study," said American Heart Assn. President Robert O.
Bonow, MD. "Instead, we hope that the public will continue to rely on the
guidance of organizations such as the American Heart Assn. that look at
all the very best evidence before formulating recommendations."
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ADDITIONAL INFORMATION:
Weblink
Atkins Center for Complementary
Medicine. (http://atkinscenter.com/)
American Heart Assn.
(http://www.americanheart.org/)
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Copyright 2002 American Medical Association. All
rights reserved.
