Time-restricted feeding extends healthspan in both sexes and lifespan in male C57BL/6 J mice

Time-restricted feeding (TRF) aligned with an organism's circadian rhythm has been shown to improve health, but its long-term effects on healthspan and lifespan in mammals, especially under standard dietary conditions that do not promote obesity, remain unclear. Here, we examined the impact of 12-h and 8-h nightly TRF windows in 264 male and 264 female C57BL/6 J mice fed regular chow. TRF improved multiple health measures, including behavioral rhythmicity, body weight and composition, frailty, and disease onset. These effects were most pronounced in the 8-h TRF group, which exhibited voluntary caloric restriction in addition to time restriction. A composite Healthspan Index revealed that TRF extended healthspan in both sexes, though the benefits were more prolonged in female mice relative to their total lifespan. Median lifespan was significantly extended in male mice under 8-h TRF by 12%, whereas female mice showed no significant lifespan extension. These results demonstrate sex-specific effects of TRF on mammalian aging.