The Science of Dietary Protein Requirements
Dietary proteins are polypeptides composed of amino acids, including the nine Essential Amino Acids (EAAs) like leucine that the human body cannot synthesize endogenously. Protein drives Muscle Protein Synthesis (MPS), cellular repair, hormonal signalling, and immune defense.
RDA vs. Optimal Athletic Intake
The Recommended Dietary Allowance (RDA) of 0.8 g/kg represents the statistical threshold required to prevent pathological nitrogen deficiency in sedentary adults. However, for active adults, resistance trainees, and older populations combating sarcopenia, optimal metabolic function requires considerably higher thresholds.
Muscle Hypertrophy Thresholds
A landmark 2018 meta-analysis published in the British Journal of Sports Medicine (Morton et al.) demonstrated that protein intakes up to 1.62 g/kg/day (with individual upper limits around 2.2 g/kg/day) maximize resistance training adaptations. Intakes beyond this plateau yield diminishing returns for muscle hypertrophy.
Protein Timing & Leucine Trigger
Spreading total protein evenly across 3 to 5 meals throughout the day (providing ~20-40g of high-quality protein containing at least 2.5-3.0g of leucine per serving) ensures continuous activation of the intracellular mTORC1 pathway, promoting optimal recovery and net nitrogen balance.