New NHLBI clinical guidelines for obesity and overweight: will they promote health?

Abstract

The purpose of this study was to assess the justification, on the basis of mortality, of the new National Heart, Lung, and Blood Institute (NHLBI) guidelines on obesity and overweight and to discuss the health implications of declaring all adults with a body mass index of 25 through 29 "overweight." The relationships between NHLBI body mass index categories and mortality for individuals older than 31 years were analyzed for 6253 Alameda County Study respondents aged 21 through 75 years. Time-dependent proportional hazards models were used to adjust for changes in risk factors and weight during follow-up. Adjusted relative risks of mortality for 4 NHLBI categories compared with the category "normal" indicated that only being underweight or moderately/extremely obese were associated with higher mortality. Specific risk varied significantly by sex. Our results are consistent with other studies and fail to justify lowering the overweight threshold on the basis of mortality. Current interpretations of the revised guidelines stigmatize too many people as overweight; fail to account for sex, race/ethnicity, age, and other differences; and ignore the serious health risks associated with low weight and efforts to maintain an unrealistically lean body mass.