How much protein do you actually need to build muscle?

The evidence-led answer

The short answer

If you do resistance training and want to build muscle, total protein across the whole day is what matters. Pooled trial data suggests the gains from adding more protein flatten out at around 1.6 g of protein per kilogram of bodyweight per day, about 112 g for a 70 kg person, with a lot of variation between individuals. Eating well above that is not harmful in healthy people, but it does not build extra muscle. Most people can hit the target from ordinary meals; a protein shake is a practical way to close a gap, not something you have to buy.

Why protein matters for training

Muscle is constantly being broken down and rebuilt. Resistance training is the signal to build; dietary protein supplies the raw material. Do one without the other and you get less of a result. Protein is one input, not the whole equation, it only makes sense alongside training hard enough, often enough.

How much, the number and the range

The most cited synthesis is a 2018 systematic review, pooled analysis and meta regression of 49 randomised trials. Adding protein produced a small increase in one rep max strength (+2.49 kg) and in fat free mass (+0.30 kg) over the training period. A breakpoint analysis found no further gain in fat free mass once total protein intake reached about 1.62 g/kg/day, with a wide confidence interval, the ceiling is a rough centre of a broad range, not a precise threshold. Practical position stands put the useful daily range at roughly 1.4 to 2.0 g/kg/day.

How the answer changes for different people

• Older adults: the evidence for an added protein supplement is mixed, not a reason to automatically aim above a general training range. Ten Haaf 2018 found no added benefit in non-frail older adults, most of whom already ate enough protein; Ma 2025 reported benefits alongside resistance training. These reviews require appraisal together rather than treating either result as universal. Findings in people with diagnosed sarcopenia concern a different population. Low intake, frailty or diagnosed muscle loss should be discussed with a clinician or dietitian rather than handled as a generic training adjustment.
• Trained vs untrained: resistance trained people get more out of added protein than beginners. A new lifter's progress is driven mostly by the training itself.
• Energy intake is the precondition: in a 10 day trial with a large (40%) energy deficit, muscle protein synthesis fell regardless of whether protein was 1.2 or 2.4 g/kg/day, resistance exercise, not extra protein, blunted the drop. Protein cannot fully offset a big energy deficit. This article is not about weight loss or calorie deficit strategies.

Food or powder?

At a matched daily total, whole food protein and supplemental protein appear broadly interchangeable for building muscle, the supplement is a convenience, not a separate mechanism. A shake (around 20 to 25 g per serving) is genuinely useful when appetite is low, you are travelling, or a day is otherwise going to fall short, not as a default. A portion of a protein food at each meal usually gets most people to the target.

Timing and spreading it out

Daily total comes first. After that, spreading protein across roughly 3 to 4 meals is a reasonable default; the exact grams per meal matter less than hitting the total. The anabolic window right after training is much wider than supplement marketing implies.

Is more better? Is it safe?

• More muscle? No. Above the ~1.6 g/kg/day region, extra protein has not been shown to add fat free mass.
• Kidneys: in healthy adults, higher protein diets did not adversely affect measured kidney filtration in a 2018 pooled analysis. This does not apply to people who already have kidney disease or reduced kidney function.

Who should check with a clinician first

This article is general information, not medical advice. Talk to a doctor, dietitian, or pharmacist before making a large change to protein intake if you have kidney disease or reduced kidney function, are pregnant or breastfeeding, have a chronic health condition, or take medication that affects the kidneys. If food, eating, or hitting macros feels stressful or controlling, that is worth talking to a professional about, this article is about training support, not a set of eating rules.