To build muscle effectively, most people need about 1.6 grams of protein per kilogram of body weight per day. For a 180-pound (82 kg) person, that works out to roughly 130 grams daily. Going higher, up to 2.2 g/kg/day, falls within the confidence interval for maximizing gains, but the evidence suggests returns diminish sharply beyond that 1.6 g/kg threshold.
The Daily Target That Matters Most
A large meta-analysis of resistance training studies found that protein supplementation stopped producing additional muscle growth beyond 1.6 g/kg/day. The International Society of Sports Nutrition sets a slightly wider range of 1.4 to 2.0 g/kg/day as sufficient for most exercising individuals. In practical terms, here’s what 1.6 g/kg looks like at different body weights:
- 140 lbs (64 kg): ~102 g protein per day
- 160 lbs (73 kg): ~117 g protein per day
- 180 lbs (82 kg): ~131 g protein per day
- 200 lbs (91 kg): ~146 g protein per day
- 220 lbs (100 kg): ~160 g protein per day
These numbers assume you’re at a roughly normal body fat percentage. If you’re carrying significant extra body fat, basing the calculation on your goal weight or lean body mass gives a more useful figure.
One situation where going higher makes sense: cutting weight. When you’re eating fewer calories than you burn, your body is more likely to break down muscle for energy. During a calorie deficit, protein intakes of 2.3 to 3.1 g/kg/day help preserve lean mass. That’s substantially more protein than you’d need while eating at maintenance or in a surplus.
How Much Protein Per Meal
Your body can only use so much protein at once to stimulate muscle repair. For younger adults, about 20 to 40 grams of high-quality protein per meal (roughly 0.25 to 0.4 g/kg of body weight) is enough to maximize that post-meal muscle-building response. Eating 60 or 80 grams in a single sitting isn’t wasted, since your body still absorbs and uses the amino acids, but the muscle-building signal doesn’t scale up proportionally.
The key amino acid driving that signal is leucine, which acts as a trigger for muscle protein synthesis. You need roughly 1.7 to 3.5 grams of leucine per serving to flip that switch. Most animal proteins hit that threshold easily in a 25 to 30 gram serving. Plant proteins can get there too, but you may need a slightly larger portion or a blend of sources to match the leucine content.
Spacing your protein across three to four meals, roughly three hours apart, appears to optimize the muscle-building response throughout the day. This matters more than obsessing over a post-workout window. If your total daily intake hits the target and you’re spreading it reasonably across meals, you’re covering your bases.
Plant Protein vs. Animal Protein
Multiple studies comparing plant-based proteins (rice, pea, soy) to whey protein have found no meaningful differences in body composition or strength gains when the total protein and essential amino acid content are matched. Whey doesn’t have unique muscle-building properties beyond its amino acid profile. The practical takeaway: if you eat enough total protein from plant sources and get adequate essential amino acids, you can build muscle just as effectively.
That said, some research has found slight advantages for whey or milk protein over soy in isolation. The likely explanation is the lower leucine density in certain plant proteins. If you rely heavily on plant-based sources, aiming for the higher end of the daily range (closer to 2.0 g/kg) or choosing leucine-rich options like soy and pea protein can close any gap.
Protein Needs After Age 50
Older adults face what researchers call anabolic resistance: the same dose of protein that triggers a strong muscle-building response in a 25-year-old produces a blunted response in someone over 60. The difference is significant. Older adults need roughly 68% more protein per meal to achieve the same muscle-building stimulus as younger people. That translates to about 40 grams of high-quality protein per meal, compared to 20 grams for younger adults.
The standard dietary recommendation of 0.8 g/kg/day was designed to prevent deficiency, not to support muscle maintenance in aging bodies. Current evidence supports 1.0 to 1.5 g/kg/day as a more appropriate target for older adults who want to maintain or build muscle. For a 160-pound older adult, that’s 73 to 109 grams per day, ideally split into meals of at least 35 to 40 grams each.
Pre-Sleep Protein
Eating protein before bed can extend the muscle-building window into overnight hours, especially if you trained that evening. In studies using 30 to 40 grams of slow-digesting protein (like casein, found in cottage cheese and casein supplements) before sleep, overnight muscle protein synthesis rates increased meaningfully. When that pre-sleep protein was combined with an evening resistance training session, the muscle-building response was 37% higher than pre-sleep protein alone.
This doesn’t mean a bedtime protein shake is mandatory. It’s most useful if you train in the evening or if you’re struggling to hit your daily protein target across regular meals. A cup of Greek yogurt or cottage cheese before bed is a straightforward way to add 20 to 30 grams without much effort.
Is Too Much Protein Harmful?
For healthy adults with normal kidney function, protein intakes in the 1.6 to 2.2 g/kg range have no established negative effects on kidney health. Even intakes above 3.0 g/kg/day have been studied in resistance-trained individuals without evidence of kidney damage.
The concern is different for people with existing kidney issues. Anyone with a single kidney or reduced kidney function is generally advised to stay below 1.2 g/kg/day. If you have any history of kidney problems, that’s worth discussing with your doctor before adopting a high-protein diet.
Beyond safety, the practical question is whether very high protein intakes help. The evidence points to diminishing returns. Going from 0.8 to 1.6 g/kg makes a large difference for muscle growth. Going from 1.6 to 2.5 g/kg makes little to no additional difference in muscle size, though it may slightly help with fat loss. For most people, the sweet spot sits right around 1.6 g/kg, with the upper end of 2.2 g/kg serving as a reasonable ceiling for those who want extra insurance.