Training Status Impacts Metabolic Response to A High-Protein Weight Loss Diet in Recreationally Resistance-Trained Females.

This study investigated the effects of a novel high-protein diet template on postprandial metabolism and body composition (e.g., waist and hip circumference, body fat (%), fat mass, fat-free mass) in recreationally resistance-trained females. Fifteen females adhered to an eight-week high-protein dietary intervention (~1.5-1.6 g·kg·day) administered via template format. Pre- and post-intervention visits included anthropometrics, measurement of body composition, and an acute high-fat meal challenge. The high-fat meal challenge (61% fat) consisted of fasting postprandial blood glucose, resting metabolic rate (RMR), fat and carbohydrate oxidation assessed at 60-, 120-, and 180-minutes. Participants were split into high (HTF; 5-6 days·week of resistance training; = 8) and low-training frequency (LTF; 2-3 days·week of resistance training; = 7) groups. All metabolism data were assessed as absolute (kcal or g) and relative (kcal or g·kg·FFM·minutes) to fat-free mass. Post-intervention, there was a significant reduction in HTF waist circumference ( 0.044), LTF body fat % ( 0.012), and LTF fat mass ( 0.014). Post-intervention, HTF females had significantly lower absolute RMR area under the curve (AUC) than LTF females ( 0.036). LTF females had higher absolute fat oxidation AUC compared to HTF females' pre-intervention ( 0.048) but a significant decrease in absolute ( 0.050) and relative ( 0.050) fat oxidation AUC post-intervention. LTF females had a significant increase in absolute ( 0.032) and relative ( 0.029) carbohydrate oxidation AUC pre- to post-intervention ( 0.032). For blood glucose, no significant differences between groups were detected ( > 0.05). These findings suggest that a novel high-protein diet template elicits a metabolic shift favoring carbohydrate oxidation in females engaging in low-frequency resistance training but did not alter fat and carbohydrate metabolism in females engaging in HTF resistance training.