Type of Diet Doesn't Matter, Cutting Calories Does

[Guest guest]

The following should be on interest

Ralph Giarnella MD

Southington Ct USA

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Type of Diet Doesn't Matter, Cutting Calories Does

By Crystal Phend, Staff Writer, MedPage Today

Published: February 25, 2009

Reviewed by Zalman S. Agus, MD; Emeritus Professor

University of Pennsylvania School of Medicine.

BOSTON, Feb. 25 -- Cutting calories is the key to weight loss regardless of

whether a diet emphasizes fat, protein, or carbohydrates, researchers found.

Four low-calorie diets -- differentiated by percentage of intake of those

nutrients -- all yielded an average loss of 7% of body weight at six months and

a 2.9 to 3.6 kg loss at two years (P>0.20 for all comparisons), M. Sacks,

M.D., of the Harvard School of Public Health, and colleagues reported in the

Feb. 26 issue of the New England Journal of Medicine.

Although protein is thought to provide more fullness per calorie than fat or

carbohydrates, the randomized trial showed no difference in satiety, hunger, or

diet satisfaction between groups.

These findings " give people lots of flexibility " and should shift focus back to

the basics, Dr. Sacks said. " Weight loss is very simplistically just reducing

the amount of calories that you take in, and any kind of healthy diet that

allows you to do that is the best. "

Action Points 

 

Dr. Sacks cautioned that the study did not test the Atkins, Mediterranean, or

other popular diets per se. " You might say we tested the science that is behind

those diets. "

Many of the claims for these diets have been based on selectively cited

short-term or animal studies of the benefits of one macronutrient over the other

for weight loss, he noted in an interview.

But the randomized trial results should be the final word in the macronutrient

debate, Dr. Sacks said. " The way forward isn't to really start tweaking dietary

composition. "

In an accompanying editorial, Martijn B. Katan, Ph.D., of VU University in

Amsterdam, agreed that community and policy initiatives should now take the

front seat.

He noted that body mass index still averaged 31 to 32 kg/m2 and was on the rise

at two years in the trial.

" Even these highly motivated, intelligent participants who were coached by

expert professionals could not achieve the weight losses needed to reverse the

obesity epidemic, " Dr. Katan wrote.

" Evidently, " he said, " individual treatment is powerless against an environment

that offers so many high-calorie foods and labor-saving devices. "

He cautioned, too, that the achieving the dietary composition targets was

difficult even in the highly supportive trial setting.

The researchers enrolled 811 overweight adults and randomized them to one of

four diets with fat, protein, and carbohydrates accounting for differing

percentages of energy as follows:

    * A low-fat, average-protein diet with 20% fat, 15% protein, and 65%

carbohydrates

    * A low-fat, high-protein diet with 20% fat, 25% protein, and 55%

carbohydrates

    * A high-fat, average-protein diet with 40% fat, 15% protein, and 45%

carbohydrates

    * A high-fat, high-protein diet with 40% fat, 25% protein, and 35%

carbohydrates

All the diets were individually targeted to restrict caloric intake by a deficit

of 750 kcal a day from baseline.

Similar foods were used for the diets along with two years of weekly group and

bimonthly individual instructional sessions.

However, Dr. Katan noted that these dietary goals were only partly achieved.

Protein intake differed by only 1% to 2% of energy rather than the intended 10%

between the high- and average-protein-diet groups and the range in carbohydrate

content between diet groups was 6% of energy instead of the planned 30%.

After the full two years, weight loss was similar whether patients' diet aimed

for high- or average-protein intake (3.6 versus 3.0 kg, P=0.22 overall and

P=0.11 among completers).

Average weight loss at two years was identical for the high- versus low-fat

diets (both 3.3 kg, P=0.94 overall and P=0.76 among completers).

Likewise, carbohydrate targets from 35% to 65% had no significant effect on

patients' ability to shed pounds.

Waist circumference changes were statistically similar between diet groups as

well.

The strongest predictor of weight loss was actually attendance at group sessions

(0.2 kg for every session attended) across diet groups (P=0.22 for difference in

slopes).

Exploring these behavioral and individual differences -- such as why the 23% of

patients who had continual weight loss through two years were so successful --

may be the real key to weight loss rather than dietary composition, Dr. Sacks

concluded.

The study was supported by grants from the National Heart, Lung, and Blood

Institute and the National Institutes of Health.

One coauthor reported conflicts of interest with Anian, Bristol-Myers Squibb,

Clarus Health, Encore Pharmaceutical, Leptos Biomedical, MDRNA, Novo Nordisk,

General Nutrition Corporation, Catalyst, Craig, Orexigen, Lithera, and

Basic Research, BAROnova, Lazard, and Biologene.

Dr. Sacks reported being a member of a group that interacts with the Obesity

Committee of the National Heart, Lung, and Blood Institute and vice-chair of the

Nutrition Committee of the American Heart Association, which advises the

Association on nutrition topics, including those related to overweight and

obesity.

Dr. Katan reported no conflicts of interest.

Primary source: New England Journal of Medicine

Source reference:

Sacks FM, et al " Comparison of Weight-Loss Diets with Different Compositions of

Fat, Protein, and Carbohydrates " N Engl J Med 2009; 360: 859-73.

Additional source: New England Journal of Medicine

Source reference:

Katan MB " Weight-Loss Diets for the Prevention and Treatment of Obesity " N Engl

J Med 2009; 360: 923-25.

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