Federal study of diets concludes: Eat less

Confronted by competing claims, scientists want data

By Elizabeth Cohen
CNN Medical Correspondent

WASHINGTON (CNN) -- Walk into any book store, and you'll be bombarded with weight loss books, some claiming low-fat diets will help you shed pounds, others touting high-protein diets.

A study out Wednesday from the federal government concludes that both kinds of popular diets work -- at least in the short-term -- not because they have any special secrets, but simply because both types of diets force you to eat fewer calories.

"The main thing in weight loss is calories in versus calories out," said Judith Stern, professor of nutrition and internal medicine at the University of California-Davis, who reviewed the report by the U.S. Department of Agriculture. "People go on fad diets and think, 'This one will be different,' but it never is and their weight rebounds and they move on to the next fad diet."

The USDA set out last year to study popular diets because of the huge number of diet books -- the agency said a search on Amazon.com yielded 1,214 -- and the relative dearth of scientific information on whether these diets work.

"Surveys consistently show that most Americans are trying to lose or maintain weight," according to the report. "The proliferation of diet books is nothing short of phenomenal."

The next step, according to the USDA report, is to conduct studies pitting protein diets against low-fat diets to see which works better long-term for weight loss and health promotion.

Researchers have applauded the USDA's decision to scientifically study popular diets.

"The whole point of science is to help people sort out conflicting science, and nowhere is there more conflicting claims than in the area of diet," said Dr. Dean Ornish, an advocate of low-fat diets. "It's important to bring together good scientists. Good scientists say, 'Show me the data.'"

U.S. to unveil new dietary guidelines next week
May 26, 2000

USDA's Food Safety and Inspection Service
Center for Food Safety and Applied Nutrition
FTC Consumer Alert on diet claims

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