low-carbohydrate diet may help obese people shed some weight faster
than a standard low-fat diet, but over time there may not be a big
difference, according to the findings from two studies published in the
May 22nd issue of The New England Journal of Medicine.
In one study, Dr. Frederick Samaha, from the Philadelphia Veterans
Affairs Medical Center, and colleagues found that obese volunteers who
consumed a low-carbohydrate diet for 6 months lost 5.8 kg, compared
with only 1.9 kg for people on a low-fat diet (p = 0.002).
In a second study, obese people on a low-carbohydrate diet lost nearly
4% more body weight after 6 months than volunteers on a conventional
diet, lead author Dr. Gary D. Foster, from the University of
Pennsylvania in Philadelphia, and colleagues note.
However, by the end of the 1-year study period, the weight loss
differences between the two groups had largely disappeared, suggesting
that low-carbohydrate diets are no better than conventional diets at
helping obese people lose weight.
"The average weight loss was greater in the low-carbohydrate groups
than in the low-fat groups, but the difference was no longer
significant at 12 months in the trial in which follow-up lasted that
long," Dr. James Ware, from Harvard University in Boston, wrote in a
Dr. Ware also noted that the weight lost in each study was relatively
small compared with the volunteers' size. The average starting weight
among the volunteers in the first study was about 130 kg. The baseline
weight of subjects in the second study was about 98 kg.
In the United States, about 45% of women and 30% of men are on a diet.
More than 60% of Americans are overweight and more than 30% are obese.
Low-carbohydrate diets have been criticized because their high fat
content may increase the risk of heart disease, kidney problems and
Findings from the 12-month study indicate, however, that triglyceride
levels fell further and HDL cholesterol levels rose higher with the
low-carbohydrate diet than with the low-fat diet.
Still, Dr. Samaha's team notes that further "studies evaluating
long-term cardiovascular outcomes are needed before a
carbohydrate-restricted diet can be endorsed."
Referrence: N Engl J Med 2003;348:2074-2090