Ask five different people how much protein you need to build muscle and you'll likely get five different answers, ranging from modest recommendations to numbers that would require several kilograms of chicken breast a day. The research on this question is actually fairly well-established, even if gym culture has a habit of rounding up.
The Core Number: 1.6-2.2g Per Kilogram of Bodyweight
The bulk of research on resistance-trained individuals converges on a range of roughly 1.6 to 2.2 grams of protein per kilogram of bodyweight per day for maximizing muscle protein synthesis. Below this range, you're likely leaving muscle growth on the table; above it, additional protein produces increasingly diminishing returns.
More protein beyond roughly 2.2g/kg does not appear to meaningfully accelerate muscle growth in most trained individuals — the body can only make productive use of so much at a time.
For a 75kg person, this works out to roughly 120-165g of protein per day — a genuinely achievable number through a combination of whole food and, if needed, a protein supplement to close any gaps.
Why the Range Exists, Not Just a Single Number
Several factors shift you toward the higher or lower end of the range:
- Calorie deficit: when cutting, protein needs trend toward the higher end (2.0-2.2g/kg) to help preserve muscle mass
- Training experience: more advanced lifters may benefit from slightly higher intakes than beginners, who tend to respond well even at the lower end of the range
- Body composition: the range is most accurate relative to lean body mass rather than total bodyweight, meaning higher body-fat individuals may not need to scale protein linearly with total weight
What About Very High-Protein Diets?
Some popular advice pushes protein intake well above 3g/kg, often based on the reasoning that "more is always better" for muscle. The research doesn't strongly support this for most people — intakes beyond roughly 2.2g/kg generally don't produce meaningfully faster muscle growth, and the extra protein is simply used for energy or, if calories are already in surplus, has no unique advantage over other macronutrients for that purpose.
Practical framing: think of 1.6g/kg as the point where most of the muscle-building benefit is already captured, and 2.2g/kg as a reasonable ceiling that covers extra margin for people in a deficit or with higher training demands — not a floor you must clear before results happen.
Protein Distribution Across the Day
Beyond the daily total, how you spread protein intake across the day appears to matter for maximizing muscle protein synthesis. Research suggests roughly 0.3-0.4g/kg per meal, spread across 3-5 meals or servings, is more effective at stimulating muscle protein synthesis repeatedly throughout the day than concentrating the same total into one or two very large servings.
Do Vegetarians and Vegans Need More Protein?
Plant protein sources are generally slightly less efficiently utilized for muscle protein synthesis than animal sources, largely due to differences in amino acid profiles (particularly leucine content) and digestibility. This doesn't mean vegetarians and vegans can't build muscle effectively — it means the practical daily target may sit slightly higher (some research suggests up to 10-20% more), and combining varied plant protein sources (legumes, grains, soy) helps cover a more complete amino acid profile.
Building a Realistic Daily Protein Plan
A practical approach for most trained individuals:
- Calculate your target using 1.6-2.2g/kg of bodyweight (higher end if cutting)
- Prioritize whole food protein sources across 3-5 meals per day
- Use a whey or plant protein supplement to close any remaining gap, rather than as the primary source
- Reassess as bodyweight or training goals change, since the target shifts with them
- Most research supports 1.6-2.2g of protein per kilogram of bodyweight per day for maximizing muscle growth.
- Protein needs trend higher within that range during a calorie deficit to help preserve muscle mass.
- Intakes well beyond 2.2g/kg generally don't produce meaningfully faster muscle growth for most people.
- Spreading protein across 3-5 meals appears more effective than concentrating it into one or two large servings.
- Vegetarians and vegans may benefit from a slightly higher target and a varied mix of plant protein sources.
Is it harmful to eat more protein than I need?
For most healthy individuals, moderately exceeding your protein target isn't harmful — it's simply used for energy rather than providing extra muscle-building benefit. People with existing kidney conditions should consult a doctor about appropriate intake.
Can I build muscle on less than 1.6g/kg of protein?
Some muscle growth is still possible below this range, particularly for beginners, but research suggests it's a less efficient use of your training effort compared to hitting the 1.6-2.2g/kg range.
Do I need a protein supplement to hit my target?
Not necessarily — whole foods can cover your full target. A supplement is simply a convenient, calorie-efficient way to close gaps when whole food alone falls short of your daily number.