How much protein do you actually need to build muscle?

Protein is the building block of muscle, and eating enough of it is genuinely important for muscle gain. But the fitness industry has significantly exaggerated how much is needed — and the science provides a clear, evidence-based answer that is lower than most gym advice suggests.

What the research actually says

The most comprehensive meta-analyses on protein intake and muscle gain — including a widely cited 2018 analysis published in the British Journal of Sports Medicine covering 49 studies — found that the benefits of protein for muscle growth plateau at approximately 1.62 grams per kilogram of body weight per day. Beyond this threshold, additional protein does not meaningfully increase muscle gain. The upper end of the range where some additional benefit may exist is around 2.2 grams per kilogram. Beyond that, the excess protein is simply used as energy.

The 1g per pound myth

A common recommendation in bodybuilding culture is to eat one gram of protein per pound of body weight — which equates to 2.2 grams per kilogram. This has become so deeply embedded in fitness culture that it feels like established science, but the evidence does not support it as a meaningful threshold for muscle growth. It is not harmful to eat this amount, but it is not necessary. Most people would build just as much muscle eating considerably less.

Timing and distribution

How you distribute protein across the day matters more than most people realise. Research suggests that muscle protein synthesis is optimised by consuming roughly 0.3 to 0.4 grams of protein per kilogram of body weight per meal — spread across 3 to 5 meals. Consuming all your daily protein in one or two sittings is less effective than spreading it out. This is because muscle protein synthesis has a ceiling per meal — beyond a certain amount, the excess amino acids are simply oxidised for energy rather than used for muscle repair and growth.

Protein quality

Not all protein sources are equal. Animal proteins — meat, fish, eggs, dairy — tend to have complete amino acid profiles and high leucine content, which is particularly important for triggering muscle protein synthesis. Plant proteins are often lower in leucine and may be missing one or more essential amino acids. This does not mean plant-based diets cannot support muscle gain — they can — but it means plant-based eaters may benefit from eating at the higher end of the protein range and combining protein sources to ensure a complete amino acid profile.

The bottom line

Aim for 1.6 to 2.2 grams of protein per kilogram of body weight per day, spread across 3 to 5 meals. For most people, this is significantly less than gym culture suggests, and it is achievable without protein supplements — though supplements are a convenient way to hit targets if whole food intake is difficult. Protein matters enormously for muscle gain. But more protein beyond the research-supported ceiling does not build more muscle — it just costs more.