The biological process of building new muscle protein, stimulated by resistance exercise and dietary protein intake.
Updated Sep 26, 2026
Muscle protein synthesis (MPS) is the process your body uses to build new muscle protein. Its main triggers are resistance exercise and enough protein, especially leucine-rich protein. That's why strength training and adequate protein together help you keep or build lean mass during GLP-1 treatment better than either one alone.
After a protein-containing meal, the rate of MPS climbs, peaks, and then levels off. It's near-maximally stimulated at roughly 0.4 g/kg of body weight per meal, and eating far more in one sitting adds proportionally less. Your body still absorbs the extra protein, though. The ceiling applies to the rate of muscle building, not to absorption, and that's where the "30g of protein per meal" myth goes wrong. What reliably drives MPS is hitting your daily protein total and training your muscles. See strength training and protein, fat, and carbohydrates.
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Related terms
Resistance training (progressive overload) — Exercise that loads your muscles against resistance and is made gradually harder over time (progressive overload) to keep or build muscle and strength.
Sarcopenia — The age- or illness-related loss of muscle mass and strength — a risk to monitor for during rapid weight loss.
Lean mass — Body weight from everything other than fat: mostly muscle, plus organs and water, and in the broad sense bone. On a DXA report, lean mass usually leaves bone out.
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