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Wednesday, January 05, 2005 :: infoZine Staff :: page views
Study Finds That Adherence to Diet, Not Type of Diet, More Important
Factor for Losing Weight A comparison of four popular diet plans finds
that the key to losing weight may not be which diet plan a person
picks, but sticking with the plan that is chosen.

HealthChicago, IL - Journal of the American Medical Association - The
study, in the January 5 issue of JAMA, also found that popular diets
can be effective for modest weight loss and reducing several cardiac
risk factors, but overall adherence rates were low.

Popular diets have become increasingly prevalent and controversial,
according to background information in the article. Many popular plans
depart substantially from mainstream medical advice, and the
effectiveness and safety of these diets have been questioned. Data
regarding the relative benefits, risks, effectiveness, and
sustainability of popular diets have been limited.

In this one year study, Michael L. Dansinger, M.D., of Tufts-New
England Medical Center, Boston, and colleagues assessed adherence rates
and the effectiveness of four popular diets for weight loss and cardiac
risk factor reduction. The diets and their principle weight loss
strategies we Weight Watchers (restriction of portion sizes and
calories); Atkins (minimize carbohydrate intake without fat
restriction); Zone (modulate macronutrient balance and glycemic load);
and Ornish (restrict fat).

This trial included 160 overweight or obese adults aged 22 to 72 years,
with known hypertension, dyslipidemia (high cholesterol), or fasting
hyperglycemia (high blood sugar). Participants were enrolled starting
July 18, 2000, and randomized to the diet groups until January 24,
2002. Forty participants were assigned to each of the diet plans. After
2 months of maximum effort, participants selected their own levels of
dietary adherence.

Assuming no change from baseline for participants who discontinued the
study, the researchers found that average weight loss at 1 year was 4.6
lbs. for Atkins (21 [53 percent] of 40 participants completed), 7.1
lbs. for Zone (26 [65 percent] of 40 completed), 6.6 lbs. for Weight
Watchers (26 [65 percent] of 40 completed), and 7.3 lbs. for Ornish (20
[50 percent] of 40 completed). Greater effects were observed in study
completers. Each diet significantly reduced the low-density
lipoprotein/high-density lipoprotein (HDL) cholesterol ratio by
approximately 10 percent with no significant effects on blood pressure
or glucose at 1 year. Amount of weight loss was associated with
self-reported dietary adherence level but not with diet type.

For each diet, decreasing levels of total/HDL cholesterol, C-reactive
protein, and insulin were significantly associated with weight loss
with no significant difference between diets.

"...all 4 diets resulted in modest statistically significant weight
loss at 1 year, with no statistically significant differences between
diets," the authors write. "In each diet group, approximately 25
percent of the initial participants sustained a 1-year weight loss of
more than 5 percent of initial body weight and approximately 10 percent
of participants lost more than 10 percent of body weight."

"...we found that a variety of popular diets can reduce weight and
several cardiac risk factors under realistic clinical conditions, but
only for the minority of individuals who can sustain a high dietary
adherence level. Despite a substantial percentage of participants who
could sustain meaningful adherence levels, no single diet produced
satisfactory adherence rates and the progressively decreasing mean
adherence scores were practically identical among the 4 diets. The
higher discontinuation rates for the Atkins and Ornish diet groups
suggest many individuals found these diets to be too extreme. To
optimally manage a national epidemic of excess body weight and
associated cardiac risk factors, practical techniques to increase
dietary adherence rates are urgently needed," the authors write.

"One way to improve dietary adherence rates in clinical practice may be
to use a broad spectrum of diet options, to better match individual
patient food preferences, lifestyles, and cardiovascular risk profiles.
Participants in our study were not allowed to choose their dietary
assignment; however we suspect adherence rates and clinical
improvements would have been better if participants had been able to
freely select from the 4 diet options. Our findings challenge the
concept that 1 type of diet is best for everybody and that alternative
diets can be disregarded. Likewise, our findings do not support the
notion that very low carbohydrate diets are better than standard diets,
despite recent evidence to the contrary," the researchers write.

JAMA Editor's Note: This study was supported by grants from the General
Clinical Research Center via the National Center for Research Resources
of the National Institutes of Health (NIH); by a grant from the NIH; a
contract from the U.S. Department of Agriculture; and a contract from
the Human Metabolic and Genetics Core Laboratory of the Boston Obesity
Nutrition Research Center program. Dr. Dansinger was supported by a
grant from the Agency for Healthcare Research and Quality.

JAMA Editorial: The Dietary Approach To Obesity - Is It The Diet Or The
Disorder?

In an accompanying editorial, Robert H. Eckel, M.D., of the University
of Colorado at Denver and Health Sciences Center, Aurora, Colo.,
discusses the findings by Dansinger and colleagues that no one diet
plan was found most effective for weight loss.

"It seems plausible that for maintenance of reduced body mass, the
right diet needs to be matched with the right patient. Ultimately, a
'nutrigenomic' approach most likely will be helpful. At present, there
are no data to help clinicians practicably match a diet to an
individual patient's 'diet response genotype.' Even beyond this
consideration, and arguably more important, once weight loss of more
than several kilograms from baseline weight occurs, a substantial
step-up in the amount of physical activity and conscientious monitoring
as part of a more comprehensive behavior modification appear
particularly important, and likely are much more relevant adaptations
than the macronutrient composition of the diet."

"Arguably, the best treatment of obesity is prevention by careful
dietary monitoring and lifestyle and choices, along with regular
physical activity. Once overweight or obesity develops, however, the
best existing evidence points toward heeding the recently released
joint lifestyle recommendations of 3 professional organizations: the
American Cancer Society, the American Diabetes Association, and the
American Heart Association, in which the recommended macronutrient mix
is built on evidence that higher intake of fruits and vegetables, whole
grains, and fish are associated with reduced incidences of diabetes
mellitus, cancer, heart disease, and stroke. Although this dietary
approach may lead to only modest weight changes, similar to the popular
diets evaluated by Dansinger et al, physicians and other health care
professions should teach obese patients that both quality and quantity
of the diet are important, and that sustained weight loss may well be
possible with the addition of physical activity and behavioral change
strategies to a modest but persistent caloric restriction-the 'Low Fad'
approach," Dr. Eckel concludes.