['To compare levels of physical function, across levels of body mass index (BMI), among middle- to older-aged women.', 'Cross-sectional study. Physical function, body weight and other covariates were measured in 1992.', "56510 women aged 45-71 y, free of cardiovascular disease and cancer, participating in the Nurses' Health Study.", 'The four physical function scores on the Medical Outcomes Study (MOS) Short Form-36 (SF36) Health Survey: physical functioning, vitality, bodily pain and role limitations.', 'After adjusting for age, race, smoking status, menopausal status, physical activity and alcohol consumption, there was a significant dose-response gradient between increasing levels of BMI in 1992 and reduced function. For example, women with a BMI between 30-34.9 kg/m2 averaged: 9.0 point lower physical functioning score (95% Confidence interval (CI) -9.5, -8.5), 5.6 point lower vitality score (95% CI: -6.1, -5.1), and 7.0 point lower freedom from pain score (95% CI: -7.6, -6.4). These declines represent an approximate 10% loss of function compared to the reference category of women with BMIs ranging from 22.0-23.9 kg/m2. For the same BMI comparison, heavier women were at 66% increased risk of limitations in ability to work or perform other roles (RR = 1.66; 95% odds ratio (OR) CI: 1.56, 1.76). These findings were replicated when the sample was restricted to women who had maintained their BMI over a ten year period.'] Are lower levels of physical functioning associated with higher body weight among middle-aged and older women?