Gender and Age Variations in Obesity in the Jackson Heart Study

In 2013-2014 in the U.S., the prevalence of obesity (body mass index (BMI)≥30 kg/m2) among African Americans was 38.2% in men and 57.2% in women, decreasing after age 60 in men but not in women. We used data from the Jackson Heart Study (JHS) to examine gender- and age-variations in prevalence of obesity as defined by BMI, waist circumference (WC), and waist-to-height ratio (WHtR). Based on data from JHS Visit 3 (2009-2013), we conducted a cross-sectional analysis of prevalence of obesity defined by BMI (≥30), WC (>88 cm among women and >102 cm among men), and WHtR (>0.5) by age and gender. We used logistic regression to evaluate associations of obesity defined by BMI (ref: BMI<25), WC (ref: ≤88 cm for women and ≤102 cm for men) and WHtR (ref: ≤ 0.5) with gender and age, adjusted for physical activity. JHS Visit 3 participants (n=3680) were 64% female and had a mean age of 62.2 years. Prevalence of obesity defined by BMI for age groups 20-49, 50-59, and ≥60 years was 67%, 67%, and 59%, respectively (p=0.005) among women; and 58%, 48%, and 40% respectively (p<0.001) among men. For the same age groups, the prevalence of obesity defined by WC was 82%, 83%, and 83%, respectively (p=0.732) for women, and 48%, 51% and 47%, respectively (p=0.540) for men; and by WHtR was 91%, 94%, and 94%, respectively (p=0.127) for women, and 87%, 87%, and 89%, respectively (p<0.001) for men. Age- and physical activity-adjusted odds ratio (aORs) for obesity among women compared to men were 2.2 (95% CI: 1.8-2.7) when based on BMI, 5.2 (95% CI: 4.5-6.1) when based on WC, and 2.0 (95% CI: 1.5-2.5) when based on WHtR. For women, physical activity-aOR for obesity per 1-year increment in age was 0.96 (95% CI: 0.95-0.97) when based on BMI but did not differ from the null when based on WC or WHtR. For men, similar physical activity-aORs for obesity per 1-year increment were observed. For both women and men, prevalence of obesity defined by BMI decreased with age but not when defined by WC or WHtR. Age-related decreases in obesity defined by BMI may not reflect decreases in obesity defined by WHtR.