(Philadelphia., PA) --
A three-center study led by researchers at the Weight
and Eating Disorders Program of the University of
Pennsylvania School of Medicine reports the results
of the first controlled trial of the Atkins Diet. The
Atkins Diet limits carbohydrates but permits unrestricted
amounts of protein and fat. Compared to a conventional,
high- carbohydrate, low-calorie approach, Atkins dieters
lost twice as much weight at 3 and 6 months but there
was no difference between the groups at one year. Despite
the lack of differences in weight loss at one year,
the Atkins dieters had significantly greater increases
in good cholesterol (HDL) and greater decreases in triglycerides.
The study, to be published in the May 22 issue of the
New England Journal of Medicine, was led by Gary
Foster, PhD Associate Professor of Psychiatry and
Clinical Director of the Weight and Eating Disorders
Program at the University of Pennsylvania Medical Center.
Samuel Klein, MD, of Washington University in St. Louis,
and James Hill, PhD, and Holly Wyatt, MD, of the University
of Colorado, were the lead investigators at the other
centers. The study investigated 63 obese men and women
who were 44 years of age and weighed an average of 216
pounds.
All participants met with a registered dietitian at
0, 3, 6 and 12 months. Those in the Atkins group were
given a copy of Dr. Atkins New Diet Revolution
and asked to follow the diet as described. The conventional
diet group was given instructional materials on a 1200-1500
calories/day (women) or 1500-1800 calories /day (men)
diet that consisted of 60% carbohydrate 25% fat, and
15% protein based on the Food Guide Pyramid. Atkins
participants lost an average of 14.7 pounds compared
with 5.8 pounds in the conventional group at 3 months;
15.2 pounds versus 6.9 pounds at 6 months; and 9.5 versus
5.4 pounds at 12 months. At one year, Atkins participants
had greater increases in HDL cholesterol (18% vs. 3%)
and greater reductions in triglycerides (-28% vs. 1%)
than did those following a conventional diet. Neither
group showed changes in LDL (bad) cholesterol at one
year .
"Obesity is a national public health problem, and we
need to evaluate alternative weight loss approaches
aggressively. Widely recommend low carbohydrate approaches
may be premature, but our initial findings suggest that
such diets may not have the adverse effects that were
anticipated," Foster stated. "The real issue is whether
low carbohydrate approaches help patients maintain their
weight loss better than conventional approaches. It
will also be important to determine whether the effects
of the diet on cholesterol are the same during weight
maintenance as they are during weight loss," Foster
also cautioned.
Results of this first, randomized, controlled study
of the Atkins diet suggest that low- carbohydrate diets
may not be as harmful as anticipated. "Larger and longer
studies are needed to assess the long-term safety and
efficacy of low-carbohydrate approaches in the management
of obesity. These preliminary data suggest that weight
losses will be comparable to conventional approaches
over a one-year period, but there may be some favorable
effects of a low-carbohydrate approach in terms of triglycerides
and HDL (good) cholesterol," Foster said.
This study was funded through grants from the National
Institutes of Health (NIH), General Clinical Research
Centers at the University of Pennsylvania, Washington
University and the University of Colorado. Others who
participated in the study at Penn were Brian McGuckin,
EdM, Research Coordinator; Philippe Szapary, MD, Assistant
Professor of Medicine, and Daniel Rader, MD, Associate
Professor of Medicine.
Similar findings for a low-carbohydrate diet by another
group of Penn faculty working at the Philadelphia Veterans
Affairs Medical Center were also reported in the May
22 issue of the New England Journal of Medicine.
In their 6-month study, Frederick Samaha, MD, and colleagues
found that a low-carbohydrate diet was associated with
greater weight losses, reductions in triglycerides and
improvements in insulin sensitivity compared to a low-calorie,
high-carbohydrate diet in 132 patients who were 53 years
old and weighed 288 pounds.
Foster and his colleagues at the Washington University
and the University of Colorado are currently enrolling
participants for a large, NIH-funded, five-year study
of low- and high-carbohydrate diets.
"This larger study of 360 participants will help us
more fully assess the benefits and risks of low-carbohydrate
diets on bone mass, kidney function, arterial function
and exercise tolerance," Foster said.
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