Fasting enhances the beneficial metabolic outcomes of exercise; however, it is unknown whether body composition is favorably modified on the short term. A baseline–follow-up study was carried out to assess the effect of an established protocol involving short-term combined exercise with fasting on body composition. One hundred seven recreationally exercising males underwent a 10-day intervention across 15 fitness centers in the Netherlands involving a 3-day gradual decrease of food intake, a 3-day period with extremely low caloric intake, and a gradual 4-day increase to initial caloric intake, with daily 30-min submaximal cycling. Using dual-energy X-ray absorptiometry analysis, all subjects substantially lost total body mass (−3.9 ± 1.9 kg; p < .001) and fat mass (−3.3 ± 1.3 kg; p < .001). Average lean mass was lost (−0.6 ± 1.5 kg; p < .001), but lean mass as a percentage of total body mass was not reduced. The authors observed a loss of −3.9 ± 1.9% android fat over total fat mass (p < .001), a loss of −2.2 ± 1.9% gynoid over total fat mass (p < .001), and reduced android/gynoid ratios (−0.05 ± 0.1; p < .001). Analyzing 15 preselected singlenucleotide polymorphisms in 13 metabolism-related genes revealed trending associations for thyroid state–related singlenucleotide polymorphisms rs225014 (deiodinase 2) and rs35767 (insulin-like growth factor1), and rs1053049 (PPARD).In conclusion, a short period of combined fasting and exercise leads to a substantial loss of body and fat mass without a loss of lean mass as a percentage of total mass.

DXA scan, male subjects, SNPs,
International Journal of Sport Nutrition and Exercise Metabolism
Department of Internal Medicine

Paoli, G.D., van de Laarschot, D., Friesema, E.C.H, Verkaik, R., Giacco, A., Senese, R., … Lange, P. (2020). Short-Term, Combined Fasting and Exercise Improves Body Composition in Healthy Males. International Journal of Sport Nutrition and Exercise Metabolism, 30(6), 386–395. doi:10.1123/ijsnem.2020-0058