Background: In samples of African Americans and the elderly adults, obesity is often not found to be a risk factor for mortality. These data contradict the evidence linking obesity to chronic disease in these groups. Our objective was to determine whether obesity remains a risk factor for mortality among long-lived black adults.
Methods: The Adventist Health Study 2 is a large prospective cohort study of Seventh-day Adventist church members who are encouraged by faith-based principles to avoid tobacco, alcohol, and meat consumption. We conducted an attained age survival analysis of 22,884 U.S. blacks of the cohort-half of whom attained an age of 58-108 years during the follow-up (adult life expectancy of 84 years in men, 89 years in women).
Results: Women in the highest body mass index quintile (>33.8) experienced a significant 61% increase (hazard ratio [95% CI] = 1.62 [1.23, 2.11] relative to the middle quintile) in mortality risk and a 6.2-year (95% CI = 2.8-10.2 years) decrease in life expectancy. Men in the highest body mass index quintile (>30.8) experienced a significant 87% increase (hazard ratio [95% CI] = 1.87 [1.28, 2.73] relative to the middle quintile) in mortality risk and 5.9-year (95% CI = 2.1- 9.5 years) decrease in life expectancy. Obesity (>30) was a significant risk factor relative to normal weight (18.5-24.9) in never-smokers. Instantaneous hazards indicated excess risk from obesity was evident through at least age 85 years. The nonobese tended to follow plant-based diets and exercise vigorously.
Conclusions: Avoiding obesity promotes gains in life expectancy through at least the eighth decade of life in black adults. Evidence for weight control through plant-based diets and active living was found in long-lived nonobese blacks.
Keywords: African American; Aging; BMI.; Black*; Caribbean; Obesity; Southern.