Importance: The effect of obesity on late-age survival in women without disease or disability is unknown.

Objective: To investigate whether higher baseline body mass index and waist circumference affect women's survival to 85 years of age without major chronic disease (coronary disease, stroke, cancer, diabetes mellitus, or hip fracture) and mobility disability.

Design, setting, and participants: Examination of 36,611 women from the Women's Health Initiative observational study and clinical trial programs who could have reached 85 years or older if they survived to the last outcomes evaluation on September 17, 2012. Recruitment was from 40 US clinical centers from October 1993 through December 1998. Multinomial logistic regression models were used to estimate odds ratios and 95% CIs for the association of baseline body mass index and waist circumference with the outcomes, adjusting for demographic, behavioral, and health characteristics.

Main outcomes and measures: Mutually exclusive classifications: (1) survived without major chronic disease and without mobility disability (healthy); (2) survived with 1 or more major chronic disease at baseline but without new disease or disability (prevalent diseased); (3) survived and developed 1 or more major chronic disease but not disability during study follow-up (incident diseased); (4) survived and developed mobility disability with or without disease (disabled); and (5) did not survive (died).

Results: Mean (SD) baseline age was 72.4 (3.0) years (range, 66-81 years). The distribution of women classified as healthy, prevalent diseased, incident diseased, disabled, and died was 19.0%, 14.7%, 23.2%, 18.3%, and 24.8%, respectively. Compared with healthy-weight women, underweight and obese women were more likely to die before 85 years of age. Overweight and obese women had higher risks of incident disease and mobility disability. Disability risks were striking. Relative to healthy-weight women, adjusted odds ratios (95% CIs) of mobility disability were 1.6 (1.5-1.8) for overweight women and 3.2 (2.9-3.6), 6.6 (5.4-8.1), and 6.7 (4.8-9.2) for class I, II, and III obesity, respectively. Waist circumference greater than 88 cm was also associated with higher risk of earlier death, incident disease, and mobility disability.

Conclusions and relevance: Overall and abdominal obesity were important and potentially modifiable factors associated with dying or developing mobility disability and major chronic disease before 85 years of age in older women.