BACKGROUND: Lifestyle interventions have been shown to improve physical function over the short term; however, whether these benefits are sustainable is unknown. The long-term effects of an intensive lifestyle intervention (ILI) on physical function were assessed using a randomized post-test design in the Look AHEAD trial. METHODS: Overweight and obese (body mass index ≥ 25 kg/m(2)) middle-aged and older adults (aged 45–76 years at enrollment) with type 2 diabetes enrolled in Look AHEAD, a trial evaluating an ILI designed to achieve weight loss through caloric restriction and increased physical activity compared to diabetes support and education (DSE), underwent standardized assessments of performance-based physical function including a 4- and 400-m walk, lower extremity physical performance (expanded Short Physical Performance Battery, SPPB(exp)), and grip strength approximately 11 years postrandomization and 1.5 years after the intervention was stopped (n = 3,783). RESULTS: Individuals randomized to ILI had lower odds of slow gait speed (