by Playfuls Staff |
7th March 2007
Premenopausal women who were assigned to follow the Atkins
diet for one year lost more weight when compared to women who were assigned to
follow the Zone, Ornish and LEARN diets, according to a study [more] in the
March 7 issue of JAMA.
Overweight and obesity are well-documented problems in the United States.
National dietary weight loss guidelines (a diet low in calories and fat, high
in carbohydrates) have been challenged, particularly by supporters of
low-carbohydrate diets. However, limited evidence has been available to
effectively evaluate other diets, according to background information in the
article.
Christopher D. Gardner, Ph.D., of Stanford
University Medical
School, Stanford, Calif.,
and colleagues examined the effects of four diets-3 popular and substantially
different diets and 1 diet based on national guidelines-representing a spectrum
of carbohydrate intake, on weight loss and related metabolic variables in
overweight and obese premenopausal women. The diets were Atkins (very low in carbohydrate),
Zone (low in carbohydrate), LEARN (Lifestyle, Exercise, Attitudes,
Relationships, and Nutrition; low in fat, high in carbohydrate, based on
national guidelines), and Ornish (high in carbohydrate). The study, which
included 311 overweight/obese (body mass index, 27-40) nondiabetic,
premenopausal women, was conducted from February 2003 to October 2005.
Participants were randomly assigned to follow for 12 months the Atkins (n =
77), Zone (n = 79), LEARN (n = 79), or Ornish (n = 76) diets and received
weekly instruction for 2 months, then an additional 10-month follow-up.
Besides weight loss, the participants were also measured for
lipid profile (low-density lipoprotein, high-density lipoprotein, and
non-high-density lipoprotein cholesterol, and triglyceride levels), percentage
of body fat, waist-hip ratio, fasting insulin and glucose levels, and blood
pressure. Outcomes were assessed at months 0, 2, 6, and 12.
The researchers found that weight loss was greater for women
in the Atkins diet group compared with the other diet groups at one year.
Average 12-month weight loss was 10.4 lbs for Atkins, 3.5 lbs. for Zone, 5.7
lbs. for LEARN, and 4.8 lbs. for Ornish. At 12 months, measurements for lipids
and levels of insulin, glucose and blood pressure for the Atkins group were
comparable with or more favorable than the other diet groups.
"Concerns about adverse metabolic effects of the Atkins
diet were not substantiated within the 12-month study period. It could not be
determined whether the benefits were attributable specifically to the low
carbohydrate intake vs. other aspects of the diet (e.g., high protein intake).
While questions remain about long-term effects and mechanisms, these findings
have important implications for clinical practice and health care policy.
Physicians whose patients initiate a low-carbohydrate diet can be reassured
that weight loss is likely to be at least as large as for any other dietary
pattern and that the lipid effects are unlikely to be of immediate concern. As
with any diet, physicians should caution patients that long-term success
requires permanent alterations in energy intake and energy expenditure,
regardless of macronutrient content," the authors conclude.
