Summary -

Key Takeaways Explained for a Non-Medical Audience

– Protein supplementation during resistance training significantly increases one-repetition maximum strength by about 2.5 kg versus control.

– Fat‑free mass increases by approximately 0.3 kg with additional protein during prolonged training.

– Muscle fiber cross-sectional area and mid‑femur muscle size both show measurable increases with protein supplementation.

– Benefits of supplementation diminish with advancing age, indicating less efficacy in older adults.

– Individuals experienced in resistance training derive greater gains—up to 0.75 kg more fat-free mass—versus novices.

– A breakpoint around 1.6 g protein per kg body weight per day marks the threshold beyond which further protein intake yields no additional muscle gains.

– Data span 49 randomized controlled trials with a combined total of 1,863 participants, strengthening generalizability.

– Meta-regression methods reinforce that resistance training itself is the dominant driver, with protein acting as a potent enhancer.

– Cross-sectional muscle hypertrophy and strength benefits appear consistent across studies with varied designs and durations.

– The dose-response relationship supports tailoring intake relative to training status and age.

– Excessive protein beyond the plateau level provides limited incremental benefit and may burden metabolic processing unnecessarily.

– Lower basal protein intake individuals benefit most from supplementation up to the plateau.

– Protein quality and timing were less central to conclusions than total daily intake within optimal range.

– Sustainable training plus targeted protein intake yields maximal adaptation efficiency.

– Personalized nutrition that factors in age and training status is key for optimizing outcomes.