Skipping breakfast regimen induces an increase in body weight and a decrease in muscle weight with a shifted circadian rhythm in peripheral tissues of mice.

Meal timing is a key factor in synchronizing the circadian clock in peripheral tissues. Circadian disorders are associated with metabolic syndrome. Previously, we demonstrated that a skipping breakfast regimen (SBR) with a high-fat diet increased body weight gain in rats. In this study, we investigated whether SBR with a normal diet led to abnormal lipid metabolism and muscle metabolism in mice. Male C57BL/6 mice were fed during ZT 12-24 in the control group and ZT 16-24 in the SBR group for two weeks. SBR mice showed increased body weight gain and perirenal adipose-tissue weight. The plantar muscle weight was decreased in the SBR group compared to that in the control group. Furthermore, SBR delayed the circadian oscillations in clock-gene expression in peripheral tissues, such as the liver, adipose tissue, and muscle, as well as the oscillations in the expression of lipid metabolism-related genes in the liver and adipose tissue. These results suggest that skipping breakfast over a long period of time is associated with a risk of obesity, metabolic syndrome, and muscle loss, such as sarcopenia.