# Combining Time-Restricted Wheel Running and Feeding During the Light Phase Increases Running Intensity Under High-Fat Diet Conditions Without Altering the Total Amount of Daily Running

## TL;DR

Restricting both eating and running to the light phase increases running intensity on a high-fat diet without changing total daily running in rats.

## Contribution

Demonstrates that time-restricted feeding and activity during the light phase can counteract some negative effects of a high-fat diet.

## Key findings

- High-fat diet increased running intensity in the light-phase group but not in the dark-phase group.
- Light-phase restriction improved muscle clock rhythms more effectively than chow-fed conditions.
- Liver clock gene expression was protected against high-fat diet effects in the light-phase group.

## Abstract

Excess caloric intake and insufficient physical activity are the two major drivers underlying the global obesity and type 2 diabetes mellitus epidemics. However, circadian misalignment of caloric intake and physical activity, as commonly experienced by nightshift workers, can also have detrimental effects on body weight and glucose homeostasis. We have previously reported that combined restriction of eating and voluntary wheel running to the inactive phase (i.e., a rat model for circadian misalignment) shifted liver and muscle clock rhythms by ~12 h and prevented the reduction in the amplitude of the muscle clock oscillation otherwise induced by light-phase feeding. Here, we extended on these findings and investigated how a high-fat diet (HFD) affects body composition and liver and muscle clock gene rhythms in male Wistar rats while restricting both eating and exercise to either the inactive or active phase. To do this, we used four experimental conditions: sedentary controls with no wheel access on a non-obesogenic diet (NR), sedentary controls with no wheel access on an HFD (NR-H), and two experimental groups on an HFD with simultaneous access to a running wheel and HFD time-restricted to either the light phase (light-run-light-fed + HFD, LRLF-H) or the dark phase (dark-run-dark-fed + HFD. DRDF-H). Consumption of an HFD did not alter the daily running distance of the time-restricted groups but did increase the running intensity in the LRLF-H group compared to a previously published LRLF chow fed group. However, no such increase was observed for the DRDF-H group. LRLF-H ameliorated light phase-induced disturbances in the soleus clock more effectively than under chow conditions and had a protective effect against HFD-induced changes in liver clock gene expression. Together with (our) previously published results, these data suggest that eating healthy and being active at the wrong time of the day can be as detrimental as eating unhealthy and being active at the right time of the day.