Voluntary exercise alters high-fat food intake and meal structure across the light-dark cycle in mice.

The timing of high-fat food intake is important for metabolic health, with consumption during the inactive phase increasing the risk of weight gain and obesity. While exercise can help restore disrupted circadian feeding patterns, its influence on high-fat food intake and meal structure across the light-dark cycle remains less understood. This study examined how brief, daily voluntary exercise affects high-fat food intake and meal structure across the light and dark periods. Mice were given 30 min of running wheel access each day during the dark (active) period and had ad libitum access to high-fat food. Intake and meal structure were analyzed separately for the light and dark periods. Exercise selectively reduced food intake during the light period, with no change during the dark period. Exercise mice also spent less time eating, had smaller and shorter meals, and exhibited an improved satiety ratio during the light period. In the dark period, exercise mice ate smaller meals but compensated by eating more frequently. These findings suggest that daily exercise promotes earlier meal termination (satiation) across the light-dark cycle but improves sustained fullness between meals (satiety) only during the light period. By shifting food intake away from the light (inactive) phase, exercise may help counteract unhealthy feeding habits associated with weight gain. Understanding how exercise interacts with circadian feeding behaviors is crucial for optimizing exercise-based strategies to improve metabolic health and appetite regulation.