The prediction of successful aging by midlife body mass index (BMI) and waist circumference (WC) was examined. BMI/WC were assessed in 4869 persons (mean age 51.2, range 42-63 in 1991/1993) and survival and successful aging (alive, no chronic disease at age >60 years, not in the worst age- and sex-standardized quintile of cognitive, physical, respiratory,cardiovascular, and mental health) ascertained over a 16-year follow-up, analyzed using logistic regression adjusted for sociodemographic factors and health behaviors. 507 participants died, 1008 met the criteria for successful aging. Those with BMI ≥ 30 kg/m(2) had lower odds of successful aging (odds ratio or OR) = 0.37; 95% confidence interval or CI: 0.27, 0.50) and survival (OR = 0.55; 95% CI: 0.41, 0.74) compared to BMI between 18.5 and 25 kg/m(2) . Those with a large WC (≥102/88 cm in men/women) had lower odds of successful aging (OR = 0.41; 95% CI: 0.31, 0.54) and survival (OR = 0.57; 95% CI: 0.44, 0.73) compared with those with a small waist (<94/80 cm in men/women). Analysis with finer categories showed lower odds of successful aging starting at BMI ≥ 23.5 kg/m(2) and WC 82/68 cm in men/women. Optimal midlife BMI and WC for successful aging might be substantially below the current thresholds used to define obesity.