['To determine the associations between body composition at baseline and knee cartilage loss over 2.9 years in older adults.', 'A total of 395 randomly selected subjects (mean 62 years, range 51-81, 50% female) were studied at baseline and 2.9 years later. T1-weighted fat-suppressed magnetic resonance imaging of the right knee was performed to determine knee cartilage volume and tibial bone area at baseline and follow-up. Height, weight and radiographic osteoarthritis were measured by standard protocols at baseline. Fat mass and lean mass were measured by dual-energy X-ray absorptiometry at baseline.', 'Tibial cartilage volume decreased by 2.0-2.7% per annum. In multivariable analysis, annual change in medial cartilage volume was negatively and significantly associated with body mass index (β: -0.14% per kg\u2009m(-2), 95% confidence interval (CI): -0.25%, -0.02%), percentage total body fat (β: -0.19% per %, 95% CI: -0.30%, -0.07%) and percentage trunk fat (β: -0.10% per %, 95% CI: -0.19%, -0.02%), and positively associated with percentage lean mass (β: 0.20% per %, 95% CI: 0.08%, 0.32%). Change in lateral tibial cartilage volume was also significantly associated with percentage total body fat (β: -0.11% per %, 95% CI: -0.21%, -0.001%) and total lean mass (β: 0.13% per kg, 95% CI: 0.04%, 0.22%). These were independent of sex and age even though both were also significant predictors.'] Is body fat associated with increased and lean mass with decreased knee cartilage loss in older adults : a prospective cohort study?