Below-normal weight may confer health benefits

NEW YORK (Reuters Health) - Even among men and women with normal weights and who are physically active, there are "statistically significant and clinically important" health benefits from minimizing their body weight, new research shows.

The risk of high blood pressure, high cholesterol, and diabetes all increase significantly with increasing body mass, report researchers from the Ernest Orlando Lawrence Berkeley National Laboratory, California in the current issue of the journal Arteriosclerosis, Thrombosis and Vascular Biology.

Dr. Paul T. Williams and colleagues also report that larger waist circumference increased the risk of high blood pressure, high cholesterol and diabetes in normal-weight men.

The findings are based on a group of 29,139 men and 11,985 women, who were runners with mostly normal weights. These subjects were monitored for more than 7 years.

During follow-up, 2,342 men (8.53 percent) and 499 women (4.26 percent) developed high blood pressure; 3,330 men (12.2 percent) and 599 women (5.14 percent) were diagnosed with high cholesterol; and 197 men (0.68 percent); and 28 women (0.23 percent) became diabetic.

Higher body mass index - the ratio of height to weight -- and waist circumference at the trial enrollment significantly increased the likelihood of normal-weight men and women developing high blood pressure and high cholesterol, and diabetes.

Williams and his associates point out, however, that the overall risks remain relatively low compared with those for overweight or obese individuals.

The lowest risk of developing high blood pressure and high cholesterol were among men and women with body mass indexes between 18.5 and 20 - indicating weights in lowest range with the normal-weight category, but not those whose leanness was "excessive and unhealthy."

The risk of developing diabetes among subjects with a BMI of 22.5 to 25 was more than 100 percent higher than among those with a BMI less than 22.5. The upper range of normal BMI is 24.9.

Williams and colleagues note that "although 36 percent of U.S. men and 42 percent of U.S. women are of normal weight, the health implications of greater weight in ostensibly normal-weight individuals are seldom acknowledged."

"Designating obesity as unhealthy does not require that we currently regard all normal weight as equally healthy," Williams and colleagues add. "Public health priorities can recognize temporal trends toward greater obesity in Americans and still acknowledge the health benefits of promoting greater leanness among normal-weight men and women."

SOURCE: Arteriosclerosis, Thrombosis and Vascular Biology, August 2007.