Comparison of two nutritional protocols in body re-composition of resistance-trained participants

This study aimed to compare the effects of two high-protein nutritional protocols (isocaloric and moderate energy deficit), combined with a structured resistance training program, to a control condition that followed the same training program without dietary intervention or supervision, on body recomposition outcomes. One protocol generated a caloric deficit and the other protocol used an isocaloric diet. Thirty participants (23.0 ± 3.4 years, 174.3 ± 8.0 cm, 80.3 ± 16.0 kg, 26.3 ± 4.5 kg·m− 2) were randomized into one of three nutritional conditions: an isocaloric diet group (ISO = 10), energy deficit group (DEF = 10) or a control group without nutritional supervision. Participants in ISO and DEF performed resistance training 4 days a week for 10 weeks and consumed nutritional protocols that contained the same amounts of protein but with different amounts of total calories. Body composition was assessed by dual X-ray densitometry at baseline and post-study. DEF reduced fat mass (FM; Δ = − 2.94 kg; p < 0.001) and fat-free adipose tissue (FFAT; Δ = − 0.47 kg; p = 0.016), while ISO showed smaller decreases (FM: Δ = − 1.41 kg; p = 0.051; FFAT: Δ = − 0.25 kg; p = 0.054). Fat-free mass (FFM) increased in both ISO (Δ = 0.97 kg; p < 0.001) and DEF (Δ = 1.04 kg; p = 0.009), as did FFM adjusted for FFAT (FFM − FFAT; ISO Δ = 1.22 kg; p = 0.002; DEF Δ = 1.50 kg; p < 0.001), whereas the control group showed no meaningful changes (all p ≥ 0.778). The Time × Group interaction was significant for FFM (p = 0.034) and FFM − FFAT (p = 0.006), but not for FM or FFAT (p > 0.05). Both a moderate energy deficit and a maintenance-calorie high-protein diet can elicit body recomposition when compared to habitual practice, suggesting that elevated protein intake (2.5 g·kg⁻1·d⁻1) may facilitate simultaneous improvements in fat mass and FFM. These findings challenge the traditional model of energy balance.