In fact, women actually lost a little weight when they consistently ate few fats and lots of fruits, vegetables, and grains. The finding is yet another gem mined from the huge Women's Health Initiative study.

Barbara Howard, PhD, of MedStar Research Institute in Washington, and colleagues signed up nearly 50,000 postmenopausal women aged 50-79 for the WHI Dietary Modification Trial. The majority of the women were overweight or obese and were eating diets that got 39% of calories from fat.

Forty percent of the women got intensive training and support in eating a low-fat diet with five or more servings of fruits and vegetables and six or more servings of grains. This training included 18 group counseling sessions in the first year and four sessions per year for the rest of the study. The other 60% of the women were handed a copy of U.S. dietary guidelines.

None of the women -- in either group -- was told to eat less or exercise more. In fact, they weren't specifically told to lose weight.

Even so, in the first year the women trained to eat a healthy diet lost about 5 pounds. After seven and a half years, they still weighed about a pound less than the women in the group who did not receive special training.

Restricting fat intake does not lead to weight gain, Howard and colleagues conclude. Long-term recommendations to achieve a diet lower in total and saturated fat with increased consumption of fruits, vegetables, and whole grains, and without focus on weight loss, do not cause weight gain.