Effect of alternate-day fasting combined with and without voluntary running exercise on body composition and energy metabolism in young adult, normal-weight mice.

OBJECTIVES

The effects of alternate-day fasting (ADF) on body composition and metabolic function in young, healthy and nonobese, individuals remain insufficiently understood. We investigated the effects of ADF with and without voluntary running exercise on body composition, energy metabolism, and biochemical parameters in mice.

METHODS

Eight-week-old male mice were divided into ad libitum (AL) and ADF groups, which were further divided into sedentary (SED) and voluntary wheel running exercise (EX) sub-groups. An oral glucose tolerance test (OGTT) was conducted in week 6 of the experimental period. Mice were euthanized in week 7 of the experimental period, and blood and tissue samples were collected for biochemical analysis.

RESULTS

The total food intake was significantly increased in the AL-EX group and decreased in the ADF-SED group. Voluntary running distance was reduced by ADF, particularly on feeding days. Skeletal muscle mass per body weight (BW) was reduced in ADF compared with AL. The epididymal fat weight per BW was reduced in EX and increased in ADF. OGTT results revealed that ADF and EX independently improved glucose tolerance, but their combination showed no additive effect. EX increased the synthesis of mitochondrial enzymes in skeletal muscle and hepatic triglyceride content, whereas ADF led to increased hepatic fatty acid synthase levels.

CONCLUSIONS

These findings suggest that ADF does not enhance exercise-induced improvements in body composition and may attenuate some beneficial effects of voluntary exercise in healthy young adult mice, potentially because of reduced physical activity associated with ADF.