Inner Profile

By Michael L. Dansinger

 The Article by HOWARD AND COLLEAGUES1 in this issue of JAMA, which reports on the largest,most ambitious randomized dietary intervention trial conducted to date, has concluded that a low-fat diet program does not produce weight gain.1 Despite the impressive features of this landmark study, the findings on longterm weight change are somewhat underwhelming.

The Womens Health Initiative (WHI),2 of which the Dietary Modification Trial is one component,3 is one of the most outstanding achievements in clinical research history.The National Institutes of Health established the WHI in 1991 to address the most common causes of death, disability,and impaired quality of life in postmenopausal women.This multimillion-dollar, 15-year project, involving 161 808 women aged 50 through 79 years, was designed to address many of the inequities in womens health research and provide practical information to women and their physicians about hormone therapy,calcium/vitamin Dsupplements, dietary patterns, and prevention of heart disease,cancer, and osteoporosis.

The Dietary Modification Trial component evaluated the effect of a low-fat (target 20% fat), highfruit/vegetable and grain diet on the prevention of breast and colorectal cancer and heart disease. Between 1993 and 1998, 48 835 postmenopausal women with a mean baseline age of 62.3 years,mean body mass index of 29.1, and a dietary fat intake of at least 32% of total calories (approximately the 50th percentile for fat intake) were randomly assigned to either the self-selected dietary control group or the low-fat dietary intervention, which aimed to change dietary patterns but did not encourage weightloss or caloric reduction (even though the vast majority of participantswere obese or overweight). The trial did provide a unique opportunity to examine long-term effects of an ad libitumlow-fat dietary pattern on body weight and the relationships between weight changes and specific changes in dietary components. The authors reported a 2.2-kg weight loss in theintervention group at year 1 (1.9 kg between groups) and a modest 0.4-kg difference between the groups at the 7.5-year

mark (P=.01). They concluded that a low-fat eating pattern does not result in weight gain in postmenopausal women.1The article by Howard et al1 is quick to focus attention on popular diets such as Atkins,4 the Zone,5 and Sugar Busters!,6 whose authors have blamed the current obesity epidemic in large part on the low-fat (high-carbohydrate) eating pattern advocated by most authorities during much of the past quartercentury.7,8 Does the recent study refute allegations hat the low-fat dietary approach caused weight gain on a national scale? Perhaps it does to some extent. On the other hand, despite

some successes,9-12 overall the low-fat dietary approach has been a failure with the US public, which is in desperate need of effective

obesity treatment and prevention strategies.

Did the WHI trial designers miss an opportunity to choose a better dietary intervention? Should they have encouraged specific caloric reductions in verweight and obese women? The intervention group reported a significant reduction in total fat intake of 9 percentage points (38.8% to 29.8% of calories as measured by food frequency questionnaire)with little or no change in the control group, suggesting a rather successful dietary intervention (although

not close to the 20% target). But even though the women who reduced fat intake the most maintained some modest weight loss, absent an explicitly targeted caloric reduction this approach apparently had very little effect on mean body weight long term and presumably little effect on caloric intake.

Given what was known about nutrition at study inception,the low-fat, highfruit/vegetable and grain diet seems to have been a straightforward choice. The same cannot necessarily be said for the absent caloric restriction advice for overweight and obese participants. Weight loss was not a treatment goal, but perhaps it should have been.Is it time to admit defeat? Is US society doomed to be one in which few individuals maintain normal body weight and one third of adults are obese?13 This study by Howard et al1 does little to reassure skeptics, and some see no hope on the horizon. Many believe humankind does not have the selfcontrol to counterbalance the forces that create a predictable wave of obesity in technologically advancing societies.Some believe national governments will never enact the bold policy changes that could make a dent in the obesity rates,such as substantially altering food advertising practices and creating economic incentives for vigorous adherence to lifestyle recommendations. Even modest steps such as limiting advertising of unhealthy food during childrens television programming or placing small taxes on unhealthy foods are met

Michael L. Dansinger provides articles about medicine conference. Despite the impressive features of this landmark study, the findings on longterm weight change are somewhat underwhelming

Learn Beauty Tips That Bring Out Your Natural Look

Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction

By Michael L. Dansinger

 Popular Diets have become increasingly prevalent and controversial.1 More than 1000 diet books are now available,2 with many popular ones departing substantially from mainstream medical advice.3 Cover stories for major news magazines, televised debates,and cautionary statements by prominent medical authorities4,5 have fueled public interest and oncern regarding the effectiveness and safety of such diets.6-8 Although some popular diets are based on long-standing medical advice and recommend restriction of portion sizes and calories (eg, Weight Watchers),9 a broad spectrum of alternatives has evolved. Some plans minimize carbohydrate intake without fat restriction (eg, Atkins diet),10 many modulate macronutrient balance and glycemic load (eg, Zone diet),11 and others restrict fat (eg, Ornish diet).12 Given the growing obesity epidemic,13 many patients and clinicians are interested in using popular diets as individualized eating strategies for disease prevention.14 Unfortunately, data regarding the relative benefits, risks, effectiveness, and Context The scarcity of data addressing the health effects of popular diets is an important public health concern, especially since patients and physicians are interested in using popular diets as individualized eating strategies for disease prevention.

Objective To assess adherence rates and the effectiveness of 4 popular diets (Atkins,Zone, Weight Watchers, and Ornish) for weight loss and cardiac risk factor reduction.

Design, Setting, and Participants A single-center randomized trial at an academic medical center in Boston, Mass, of overweight or obese (body mass index: mean,35; range, 27-42) adults aged 22 to 72 years with known hypertension, dyslipidemia,or fasting hyperglycemia. Participants were enrolled starting July 18, 2000, and randomized to 4 popular diet groups until January 24, 2002.

Intervention A total of 160 participants were randomly assigned to either Atkins(carbohydrate restriction, n=40), Zone (macronutrient balance, n=40), Weight Watchers(calorie restriction, n=40), or Ornish (fat restriction, n=40) diet groups. After 2 months of maximum effort, participants selected their own levels of dietary adherence.

Main Outcome Measures One-year changes in baseline weight and cardiac risk factors, and self-selected dietary adherence rates per self-report.

Results Assuming no change from baseline for participantswhodiscontinued the study,mean (SD) weight loss at 1 year was 2.1 (4.8) kg for Atkins (21 53% of 40 participants completed, P=.009), 3.2 (6.0) kg for Zone (26 65% of 40 completed, P=.002), 3.0(4.9) kg for Weight Watchers (26 65% of 40 completed, P_.001), and 3.3 (7.3) kg for Ornish (20 50% of 40 completed, P=.007). Greater effects were observed in study completers.

Each diet significantly reduced the low-density lipoprotein/high-density lipoprotein (HDL) cholesterol ratio by approximately 10% (all P_.05), with no significant effects on blood pressure or glucose at 1 year. Amount of weight loss was associated with selfreported dietary adherence level (r=0.60; P_.001) but not with diet type (r=0.07; P=.40).For each diet, decreasing levels of total/HDL cholesterol, C-reactive protein, and insulin

were significantly associated with weight loss (mean r=0.36, 0.37, and 0.39, respectively)with no significant difference between diets (P=.48, P=.57, P=.31, respectively).

Conclusions Each popular diet modestly reduced body weight and several cardiac risk factors at 1 year. Overall dietary adherence rates were low, although increased adherence was associated with greater weight loss and cardiac risk factor reductions for each diet group.

Michael L. Dansinger provides articles about health medicine. Popular Diets have become increasingly prevalent and controversial.

beauty tips

You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.