European Journal of Applied Physiology · 8 authors, 10 centres
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This study compared progressive energy restriction (PER) versus severe energy restriction (SER) in resistance-trained women performing concurrent training for 8 weeks. Both diets led to significant fat loss (PER: -1.7 kg, SER: -1.2 kg) with no significant loss of fat-free mass or strength. PER may offer better adherence and a slightly greater fat loss effect, making it a practical alternative for body composition improvement.
**Background:** Severe energy restriction (SER) is commonly used for rapid fat loss but may compromise fat-free mass (FFM) and performance, especially in athletes. Progressive energy restriction (PER) may mitigate these losses and improve adherence. However, few studies have compared these strategies in resistance-trained women. This study aimed to evaluate the effects of an 8-week concurrent training (CT) program combined with either PER or SER on body composition and strength in trained women.
**Methods:** Fourteen women (mean age 29.5±3.8 years, BMI 23.8±2.8 kg/m²) with >2 years of resistance training experience were randomly assigned to PER (n=7) or SER (n=7). Both groups performed a high-volume CT program (6 sessions/week: 4 resistance training sessions with supersets and 2 cardio sessions). The PER group started at 40 kcal/kg FFM and progressively reduced to 25 kcal/kg FFM over 8 weeks, while the SER group consumed a constant 25 kcal/kg FFM. Protein intake was high in both groups (~2.5-2.6 g/kg FFM/day). Body composition was assessed by DXA, with FFM corrected for fat-free adipose tissue (FFAT). Strength was measured via 1-RM squat and bench press, and power via countermovement jump (CMJ). Statistical analyses included paired t-tests, effect sizes (Hedges' g), and repeated-measures GLM.
**Key Results:** Both groups significantly reduced fat mass: PER by -1.7±0.4 kg (P<0.001, ES=-0.39) and SER by -1.2±0.6 kg (P=0.002, ES=-0.20). Body mass also decreased significantly (PER: -2.3±0.7 kg, P<0.001; SER: -1.6±1.2 kg, P=0.013). After correcting FFM for FFAT, no significant changes were observed in either group (PER: -0.3±0.1 kg, P=0.071, ES=-0.06; SER: -0.2±0.1 kg, P=0.578, ES=-0.04). Strength-related variables showed no significant changes: bench press (PER: -0.9±1.1 kg, P=0.095; SER: -0.9±4.6 kg, P=0.610), squat (PER: +0.6±4.3 kg, P=0.708; SER: +2.8±4.6 kg, P=0.159), and CMJ (PER: +0.5±2.1 cm, P=0.568; SER: -0.1±2.1 cm, P=0.944). No between-group differences were found for any variable. Notably, the SER group did not fully adhere to the prescribed 25 kcal/kg FFM, consuming an average of 29.5 kcal/kg FFM, while the PER group adhered more closely to their progressive targets.
**Clinical Implications:** Both PER and SER effectively reduced fat mass while preserving FFM and strength in resistance-trained women undergoing concurrent training. PER showed a modestly greater effect on fat loss (ES=-0.39 vs -0.20) and may promote better dietary adherence due to its gradual approach. Given the small sample size and lack of statistical significance between groups, these findings are preliminary. However, PER appears to be a viable and potentially more flexible strategy for body composition improvement in trained women, with lower risk of non-adherence compared to severe restriction. Future research with larger samples and longer durations is warranted to confirm these observations.