Last Updated: 2007-08-15 8:00:26 -0400 (Reuters Health)

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

"We have demonstrated that the odds for hypertension, high cholesterol, and diabetes all increase significantly with increasing BMI (body mass index) in both nonobese and normal-weight men and women," report researchers from the Ernest Orlando Lawrence Berkeley National Laboratory, California in the August issue of Arteriosclerosis, Thrombosis and Vascular Biology.

Dr. Paul T. Williams and colleagues also report that larger waist circumference predicted greater odds of hypertension, high cholesterol and diabetes in normal-weight men.

The findings are based on 29,139 male and 11,985 female primarily normal-weight runners followed prospectively for more than 7 years. During follow up, 2,342 men (8.53%) and 499 women (4.26%) developed hypertension, 3,330 men (12.2%) and 599 women (5.14%) were diagnosed with high cholesterol, and 197 men (0.68%) and 28 women (0.23%) became diabetic.

Higher BMI and waist circumference at baseline significantly increased the likelihood of normal-weight men becoming hypertensive and hypercholesterolemic (p < 0.0001 for both) and diabetic (p < 0.02). Similarly, baseline BMI and waist circumference were associated with a higher risk of hypertension (p = 0.05) among normal-weight women.

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

The smallest odds for hypertension and high cholesterol were among men and women with BMIs between 18.5 and 20 — a group well within the normal-weight BMI range (up to 25) but excluding those whose leanness is "excessive and unhealthy."

The risk of developing diabetes among subjects with a BMI of 22.5 to 25 was more than 100% higher than among those with a BMI less than 22.5.

Summing up, Dr. Williams and colleagues note that "although 36% of US men and 42% of US women are of normal weight, the health implications of greater weight in ostensibly normal-weight individuals are seldom acknowledged."

They add: "Designating obesity as unhealthy does not require that we currently regard all normal weight as equally healthy. 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."

Arterioscler Thromb Vasc Biol 2007;27:1811-1819.