Suitability of a 10% fat diet for use in time-restricted feeding experiments with C57BL/6 mice

Background: There is growing interest in the possible role of circadian rhythms in feeding behavior and their effect on diet-induced obesity. However, it is unclear whether widely used purified diets are suitable for use as normal control diets for rodents undergoing time-restricted feeding studies. In the present study, we compared the effects of 4% and 10% fat diets on body mass gain and food consumption during time-restricted feeding (TRF). Methods: Ad libitum -fed male C57BL/6J mice had free access to AIN-93M (4% fat) or modified 10% fat diets, whereas TRF groups were only able to consume one of these diets twice daily, at ZT23:00–01:00 and ZT11:00–13:00, for 5 weeks. Results: Total energy consumptions by the TRF-4% and TRF-10% fat groups were 26.5% and 18.6%, respectively, less than that of the ad libitum -fed groups. The body mass gains by the 4% and 10% fat diet groups fed ad libitum were similar, but the gain by the TRF-4% fat group was markedly lower than that of the TRF-10% fat group. In addition, whereas the body mass gain by the TRF-10% fat group was similar to that of its ad libitum equivalent, the gain by the TRF-4% fat group was much lower than that of the equivalent ad libitum -fed group. Conclusion: We showed for the first time that a 10% fat diet (21.9% kcal from fat) is suitable for the maintenance of body mass gain during TRF of C57BL/6 mice. Keywords: ad libitum feeding, fat content, mouse, time-restricted feeding