Want to Lose Weight? Just Eat Less, Diet Study Suggests

WEDNESDAY Feb. 25, 2009 -- If you want to lose weight, it doesn't seem to matter what type of diet plan you choose. What really matters is that you just eat less.

A study in the Feb. 26 issue of the New England Journal of Medicine compared a variety of diet plans -- which emphasized varying degrees of fat, protein and carbohydrates -- and found that any eating plan that causes you to consume fewer calories will help you lose weight.

"This study has a very practical, useful message," said study author Dr. Frank Sacks, a professor of cardiovascular disease prevention at the Harvard School of Public Health. "It doesn't really matter much the specific type of diet -- see what suits you best. The focus should be on reducing calories. That's what really counts."

Intense debates have raged over what type of diet plan is best. Study results on low-fat diets and high-protein diets have been mixed, with none providing conclusive evidence, according to background information in Sacks' study.

To try to answer the question of what works best, Sacks and his colleagues recruited 811 overweight people, about 40 percent of them men, from two cities -- Boston and Baton Rouge, La.

They were randomly assigned to follow one of four diets:

  • Low-fat, average-protein diet made up of 20 percent fat, 15 percent protein and 65 percent carbohydrates.
  • Low-fat, high-protein diet of 20 percent fat, 25 percent protein and 55 percent carbohydrates.
  • High-fat, average-protein plan containing 40 percent fat, 15 percent protein and 45 percent carbohydrates.
  • High-fat, high-protein diet of 40 percent fat, 25 percent protein and 35 percent carbohydrates

All groups were told to keep saturated fat to no more than 8 percent of their daily intake of calories and to try to consume at least 20 grams of dietary fiber daily. The physical activity goal was set at 90 minutes a week.

Everyone received both group and individual counseling for the two-year study period, and they entered diet and exercise information into a computer program that provided feedback on how well they were meeting their dietary goals. About 80 percent of the participants completed the study.

After six months, participants in each group had lost an average of about 13 pounds. After two years, the average weight loss was down to 6 or 7 pounds. The study participants reported similar satisfaction with their diets.

Health measures, such as blood pressure and cholesterol levels, were also similar between the groups.

"On average, no one diet was better than another," Sacks said. The bottom line if you want to lose weight, he said, is to "eat a heart-healthy diet and be very careful about how much you eat."

This might not be the end of the debate, however. In an accompanying editorial, Martijn Katan, a nutrition professor at VU University in Amsterdam, pointed out that although the researchers had anticipated that the contents of the diets would vary greatly, the actual differences in content between the plans averaged just 1 percent or 2 percent.

So, he says, he doesn't believe that the study settles the issue of diet vs. diet.

Rather, this is yet another study that shows how difficult it is to lose weight and keep it off, he said, because even these people, involved in an intensive intervention, tended to gain the weight back.

"Losing weight and keeping it off can be as tough as kicking a drug habit," Katan said. "The most important determinant of success might not be the composition of the diet. It might be whether your community promotes exercise and curbs high-calorie foods."

More information

To learn more about weight loss and nutrition, visit the government's Weight-control Information Network.

Posted: February 2009


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