Muscle Protein Synthesis
Muscle protein synthesis is the process by which amino acids are incorporated into skeletal muscle protein, and net muscle gain occurs only when synthesis exceeds breakdown across the day. Two stimuli dominate: mechanical tension from resistance training, which sensitises muscle to amino acids for up to 24 hours, and leucine-containing protein feeding, which activates the mTORC1 pathway. Around 2.5 to 3 grams of leucine per meal — roughly 25 to 40 grams of a high-quality protein — is sufficient to maximally stimulate the response in most adults, and older adults need the higher end because of anabolic resistance. Total daily protein around 1.6g per kg captures nearly all the available benefit, with little added from higher intakes. Beyond protein, creatine monohydrate is the only supplement with consistent evidence for increased lean mass and strength; HMB, BCAAs and testosterone-boosting products do not deliver in trained populations eating adequate protein.
TL;DR
Resistance training plus 1.6g protein per kg daily drives muscle protein synthesis. Creatine adds a real increment; almost every other supplement does not.
Why It Matters
Muscle mass predicts functional independence, metabolic health and mortality. Sarcopenia begins in the fourth decade and accelerates after 60, making the protein plus resistance training combination increasingly important with age.
How to Measure
DEXA is the practical standard for lean mass, with bioimpedance an accessible but less precise alternative. Function matters more than composition: grip strength dynamometry, five-times sit-to-stand, and gait speed are validated and strongly outcome-linked. Track strength progression in key lifts as the most useful day-to-day marker.
Biomarkers
Optimization Protocol
Resistance train each major muscle group two to three times weekly, taking sets close to failure and progressing load over time — this is the non-negotiable stimulus. Consume 1.6g protein per kg bodyweight daily, distributed across three to four meals of 25-40g each, with the higher end for adults over 60. Include a protein-containing meal within a few hours of training. Add creatine monohydrate 3-5g daily, which reliably increases training volume and lean mass. Ensure adequate total energy: muscle gain is very difficult in a substantial deficit.
Lifestyle Levers
- •Resistance training 2-3 times weekly with progressive overload
- •1.6g/kg daily protein
- •25-40g protein per meal
- •Creatine monohydrate 3-5g daily
- •Adequate sleep
- •Sufficient total energy intake
Supporting Supplements
Pea Protein
A legitimate whey alternative for muscle protein synthesis when total daily protein is adequate; gains require resistance training.
Casein Protein
The overnight window is real and casein is the right tool for it — but it only matters once total daily protein is already adequate.
Whey Protein
Whey maximises the acute muscle protein synthesis response better than any other common protein — but the chronic advantage largely vanishes once total daily protein is matched.
Supporting Research
Frequently Asked Questions
Typical Timeframe
8-12 weeks for measurable lean mass change; strength improves within weeks through neural adaptation
Measurable Metric
Lean body mass, grip strength, and one-repetition maximum strength
Research Summary
My Notes
Sign in to add personal notes
This information is for educational purposes only. Always consult a healthcare professional before starting any supplement regimen.