Four Weeks of Time-Restricted Feeding Combined with Resistance Training Does Not Differentially Influence Measures of Body Composition, Muscle Performance, Resting Energy Expenditure, and Blood Biomarkers

Recently, interest in time-restricted feeding (TRF) has increased from reports highlighting improvements in body composition and muscular performance measures. Twenty-six recreationally active males were randomly assigned to either TRF (n = 13; ~22.9 years; 82.0 kg; 178.1 cm; 8 h eating window, 25% caloric deficit, 1.8 g/kg/day protein) or normal diet (ND; n = 13; ~22.5 years; 83.3 kg; 177.5 cm; normal meal pattern; 25% caloric deficit, 1.8 g/kg/day protein) groups. Participants underwent 4-weeks of supervised full body resistance training. Changes in body composition (fat mass (FM), fat free mass (FFM), and body fat percentage (BF%)), skeletal muscle cross sectional area (CSA) and muscle thickness (MT) of the vastus lateralis (VL), rectus femoris, (RF), and biceps brachii (BB) muscles, resting energy expenditure (REE), muscular performance, blood biomarkers, and psychometric parameters were assessed. Significant (p < 0.05) decreases were noted in BM, FM, BF%, testosterone, adiponectin, and REE, along with significant increases in BP1RM, LP1RM, VJHT, VJPP, VLCSA, BBCSA, and BBMT in both groups. Plasma cortisol levels were significantly elevated at post (p = 0.018) only in ND. Additionally, FFM was maintained equally between groups. Thus, a TRF style of eating does not enhance reductions in FM over caloric restriction(definition) alone during a 4-week hypocaloric diet.