Time restricted feeding (TRF) reduces body weight and improves glucose tolerance in animals and humans. This study examined the effects of 10-hours of TRF initiated from lights off (zeitgiber ZT12) or after a 4-hour phase delay (akin to breakfast skipping) in mice fed a standard laboratory diet (SLD) or high-fat diet (HFD).
Eight-week old C57BL6J male mice (N=192) were provided with SLD or HFD (43% calories from fat) for 4-weeks before randomisation to one of three groups within the same diet for a further 8-weeks: ad libitum (AL); 10-hour TRF initiated at ZT12 (TRFe); 10-hour TRF initiated at ZT16 (TRFd). An oral glucose tolerance test (1g/kg body weight, N=7-8/group), body composition by echoMRI (N=6/group) and metabolic monitoring over 24 hours (Promethion system, SABLE, N=4-6/group) were carried out before tissue harvest at six time points (ZT0, 4, 8, 12, 16 and 20, N=5-6/time point). Statistics were performed by two-way ANOVA with bonferroni as post-hoc.
Body weight was reduced in TRFe and TRFd mice that were fed SLD (P<0.001) or HFD (P<0.001) and was further reduced in TRFe vs TRFd (P≤0.021). TRFe and TRFd reduced fat mass in HFD group only (P≤0.001), with significantly lower fat mass in TRFe vs TRFd (P=0.003). Glucose tolerance was improved in TRFe and TRFd mice vs AL (P≤0.04) in both diet groups, but there was no difference between TRFe and TRFd. Fasting glucose, fasting insulin and insulin AUC were lower in TRFe and TRFd vs AL mice fed HFD only (P<0.05). Energy expenditure adjusted body weight¾ was not different between groups; however, activity was increased in TRF mice.
Delaying the initiation of TRF reduced weight and fat mass losses, but did not significantly impact improvements that were observed in glucose metabolism. Further exploration of delaying TRF to increase patient acceptability is warranted.