Ineffective Expansion of 15-Minute Community Life Circles: Cross-Scale Evidence from Food and Physical Activity Environments in Aging Communities

Proximity-based planning frameworks such as the 15 min city and community life circle (CLC) are widely promoted to improve age-friendly access to essential resources, based on the assumption that enlarging spatial scale improves access. This assumption remains largely untested in high-density aging cities, where neighborhood-level deprivation may persist even as aggregate access improves. Using 3737 residential communities in central Tianjin, China, this study jointly evaluates food and physical activity environments across 5, 10, and 15 min walking thresholds. We apply a three-dimensional demand–matching–spatial association framework that combines health-weighted accessibility, location quotient matching, and bivariate spatial autocorrelation. Food access shows a continuous core–periphery gradient, whereas physical activity access is fragmented and facility-dependent. Supply–demand matching shows divergent scale responses across resource domains. Aggregate accessibility increased as the CLC scale expanded. However, 45.88% of communities classified as LL at the 10 min scale remained LL at 15 min, substantially exceeding the overall LL proportion of 18.70% at the 15 min scale. Only 5.42% of communities classified as HL or LH transitioned to HH. This divergence between aggregate accessibility improvement and persistent local disadvantage is defined as ineffective expansion. Eight diagnostic types reveal a clear divide between deprived peripheries and advantage-maintenance conditions in the urban core. These findings suggest that age-friendly CLC planning should move beyond uniform service-area expansion toward type-specific, place-based interventions.