OBJECTIVES: To determine whether the attenuation in risk of death due to excess body fat seen in most studies of older adults may be due to confounding, the relationship between adiposity and mortality was examined in adults who never smoked, were free of major chronic diseases, and maintained stable weight over long periods.
DESIGN: Prospective cohort study.
SETTING: The Adventist Health Study and Adventist Mortality Study in California.
PARTICIPANTS: Six thousand thirty adults aged 25 to 82 who had never smoked and had no history of coronary heart disease, cancer, or stroke.
MEASUREMENTS: During 29 years of follow-up, anthropometric data were collected at baseline and 17 years later, and mortality surveillance continued for 12 years thereafter. Data were analyzed using survival analysis with attained age as the time variable.
RESULTS: Instantaneous hazard plots indicated that men with a body mass index (BMI) greater than 22.3 kg/m2 and women with a BMI greater than 27.4 kg/m2 had a greater mortality risk through the ninth decade than those with lower BMI. For men aged 75 to 99 who maintained stable body weight, a BMI greater than 22.3 kg/m2 was associated with a 3.7-year (95% confidence interval (CI)=1.1–6.3) shorter life expectancy and significantly greater mortality (hazard ratio (HR)=1.88, 95% CI=1.16–3.04, for BMI=22.3–27.3 kg/m2; HR=2.00, 95% CI=1.01–3.97 for BMI>27.3 kg/m2; reference, BMI≤22.3 kg/m2). For women aged 75 to 99 who maintained stable body weight, a BMI greater than 27.4 kg/m2 was associated with a 2.1-year (95% CI=0.5–3.8) shorter life expectancy and significantly greater mortality (HR=1.12, 95% CI=0.80–1.58 for BMI<20.6 kg/m2; HR=1.41, 95% CI=1.05–1.89 for BMI>27.4 kg/m2; reference, BMI 20.6–27.4 kg/m2).
CONCLUSION: Excess body fat maintained after the seventh decade decreases life expectancy but appears to be less lethal in women.