To build muscle, most people need between 1.6 and 2.2 grams of protein per kilogram of body weight per day. That means a 75 kg (165 lb) person should aim for roughly 120 to 165 grams of protein daily while following a consistent resistance training program. This range is well above the general Recommended Dietary Allowance of 0.8 g/kg, which is designed to prevent deficiency, not to optimize muscle growth.
The Evidence-Based Range for Muscle Growth
A large meta-analysis published in the British Journal of Sports Medicine, which pooled data from 49 studies, found that protein supplementation beyond 1.62 g/kg/day produced no further gains in fat-free mass during resistance training. However, because individual responses vary, the confidence interval of that finding stretched from 1.03 to 2.20 g/kg/day. That’s why researchers suggest aiming for around 2.2 g/kg/day if your goal is to maximize every possible advantage.
The International Society of Sports Nutrition lands in a similar place, recommending 1.4 to 2.0 g/kg/day for most exercising individuals looking to build or maintain muscle. In practical terms, the difference between 1.6 and 2.2 g/kg is modest for most people. For someone weighing 80 kg, it’s the difference between 128 and 176 grams per day. Starting at 1.6 g/kg gets you the majority of the benefit; pushing toward 2.2 g/kg is a reasonable margin of safety if you want to leave nothing on the table.
Why the RDA Falls Short
The RDA of 0.8 g/kg/day represents the minimum intake needed to meet basic nitrogen balance in sedentary adults. It was never designed with muscle building in mind. If you weigh 70 kg and eat only 56 grams of protein per day (the RDA), you’re providing enough to maintain normal bodily functions but nowhere near enough to fuel the repair and growth that resistance training demands. Doubling or tripling the RDA is not excessive for someone training regularly. It’s the baseline for progress.
Higher Needs During Fat Loss
When you’re eating fewer calories than you burn, your body is more likely to break down muscle for energy. Protein intake needs to increase to counteract this. Research on athletes recommends 1.6 to 2.4 g/kg/day during a caloric deficit, with some evidence supporting intakes as high as 2.3 to 3.1 g/kg/day for resistance-trained individuals trying to preserve lean mass while cutting. Above roughly 2.4 g/kg/day, the muscle-sparing benefit appears to plateau for most people.
If you’re dieting to lose fat while keeping your muscle, erring on the higher end of the range is worthwhile. A 90 kg person cutting weight might aim for 200 grams of protein daily rather than 150.
Adjustments for Age
Older adults face a challenge: the body becomes less efficient at using dietary protein to build and repair muscle, a shift sometimes called “anabolic resistance.” The general recommendation for adults over 65 is at least 1.0 to 1.2 g/kg/day just to maintain existing muscle mass. For older adults actively training to build muscle, intakes closer to the 1.6 to 2.2 g/kg range used in younger populations are likely necessary, and some researchers suggest leaning toward the higher end to compensate for that reduced efficiency.
Muscle loss with aging (sarcopenia) accelerates after about age 50, so protein intake becomes more important, not less, as you get older.
How to Spread Protein Across Meals
Your body can only ramp up muscle repair so fast after a single meal. Research shows that muscle protein synthesis maxes out at around 30 grams of protein per sitting in younger adults, with meals containing 30 to 45 grams producing the strongest association with leg lean mass and strength. Eating 80 grams in one meal and 20 grams in another is less effective than distributing protein more evenly.
A practical target: three to four meals per day, each containing at least 30 grams of protein. For someone aiming at 160 grams daily, that might look like four meals of 40 grams each. This pattern keeps the muscle-building signal elevated throughout the day rather than spiking it once and letting it fade.
Plant-Based Protein Requires a Higher Intake
Plant proteins generally contain less of the amino acid leucine, which plays a central role in triggering muscle repair. They’re also digested and absorbed differently than animal proteins. To compensate, younger adults eating exclusively plant-based diets may need at least 20% more protein per meal to achieve the same muscle-building response as omnivores. For older adults, that gap widens to roughly 30% more.
In practice, this means a plant-based eater should aim for at least 30 grams of protein per meal (closer to 40 grams for those over 60) and may benefit from targeting the higher end of the daily range, around 2.0 to 2.2 g/kg/day or above. Combining complementary protein sources (grains with legumes, for instance) and choosing higher-leucine plant options like soy can help close the gap.
Is There an Upper Limit?
For muscle-building purposes, returns diminish sharply above about 2.2 g/kg/day when you’re eating enough total calories. Some research has explored intakes above 3.0 g/kg/day in resistance-trained individuals and found potential benefits for fat loss without negative effects on blood markers, but these intakes don’t appear to add meaningful extra muscle compared to 2.2 g/kg.
On the safety side, very high protein diets are linked to an increased risk of kidney stones. Diets heavy in red and processed meat also carry associations with higher rates of heart disease and colon cancer, though those risks are tied more to the protein source than the amount. For most healthy people without pre-existing kidney conditions, intakes up to 2.2 g/kg/day are well-tolerated. Harvard Health suggests keeping total protein at or below 2.0 g/kg of ideal body weight for the average healthy person not engaged in serious strength training.
Quick Reference by Goal
- General muscle building: 1.6 to 2.2 g/kg/day
- Muscle building during fat loss: 2.0 to 2.4 g/kg/day
- Maintaining muscle (older adults): 1.0 to 1.2 g/kg/day minimum
- Plant-based dieters: add roughly 20% to the above targets
- Per meal target: 30 to 45 g across 3 to 4 meals
These ranges assume consistent resistance training. Protein without a training stimulus won’t build muscle on its own. The two work together: training creates the demand, and protein supplies the raw material.