Muscle protein synthesis, briefly
Building muscle is a constant cycle of breakdown and repair. Resistance training creates small amounts of damage in muscle fibres; your body repairs that damage using amino acids from protein, and — given enough stimulus and enough raw material — repairs it slightly stronger than before. This process is called muscle protein synthesis, and it's the reason training without enough protein produces far slower results than training with it.
How much protein actually matters here
Research on resistance-trained individuals generally supports somewhere around 1.6–2.2g of protein per kilogram of bodyweight per day for maximising muscle growth — intakes well above that don't appear to provide further benefit for most people. Our protein calculator for muscle gain adjusts within that range based on your training intensity and age.
Total calories matter as much as protein
Protein provides the raw material for muscle growth, but it's not the only requirement — building new tissue also takes energy. Trying to build muscle in a significant calorie deficit is fighting an uphill battle regardless of how much protein you eat. Most people building muscle do best eating at maintenance or in a slight surplus, with protein intake high enough to make use of that extra energy.
Does meal timing actually matter?
The idea of a narrow "anabolic window" right after training has been largely overstated in popular fitness culture — total daily protein intake matters far more than eating protein within a specific number of minutes post-workout. That said, spreading protein across 3–4 meals through the day (rather than eating most of it in one sitting) does appear to support muscle protein synthesis better than one large dose, largely because there's a practical ceiling on how much protein a single meal can effectively use for muscle building.
Common mistakes
- Eating enough protein but not enough total calories to support growth
- Eating most protein in one meal rather than spreading it across the day
- Under-eating protein on rest days, assuming it only matters on training days (muscle repair continues well after the workout itself)
- Chasing protein intakes far above 2.2g/kg, which research doesn't support as producing extra benefit
FAQs
How much protein do I need per day to build muscle?
Most research supports roughly 1.6–2.2g per kilogram of bodyweight per day for maximising muscle growth in people doing regular resistance training. Use our muscle gain calculator for a number based on your specific details.
Do I need to eat protein immediately after a workout?
Not within a narrow window, no — total daily protein intake matters far more than precise post-workout timing. Eating protein at some point within a few hours of training is sufficient for most people.
Can I build muscle without a calorie surplus?
It's possible in some cases (particularly for beginners or people returning to training), but it's generally slower and less reliable than building muscle at maintenance or in a slight surplus.
Building muscle and want meal ideas to match?
See our 40g, 50g and 60g protein meal ideas, or let HitProtein's Protein Coach suggest meals based on your goal.