Most people need 1.6 to 2.2 grams of protein per kilogram of body weight per day to maximize muscle growth. For a 180-pound (82 kg) person, that works out to roughly 130 to 180 grams of protein daily. This range, supported by the International Society of Sports Nutrition and multiple meta-analyses, assumes you’re doing regular resistance training. Without that stimulus, extra protein alone won’t build muscle.
The Daily Target in Practical Terms
The ISSN’s position stand on protein and exercise places the effective range at 1.4 to 2.0 g/kg/day for most exercising people, while a widely cited 2018 meta-analysis by Morton and colleagues narrows the sweet spot to 1.6 to 2.2 g/kg/day for maximizing muscle protein synthesis specifically. These numbers are close enough that aiming for 1.6 g/kg is a solid minimum, with diminishing returns above 2.2 g/kg for pure muscle-building purposes.
To find your number: divide your weight in pounds by 2.2 to get kilograms, then multiply by 1.6 and 2.2. A 150-pound person (68 kg) needs about 109 to 150 grams per day. A 200-pound person (91 kg) needs about 145 to 200 grams. If you carry significant body fat and want a more conservative estimate, you can base the calculation on your lean body mass or goal weight instead.
There’s some evidence that going even higher, above 3.0 g/kg/day, may help resistance-trained individuals lose fat. But for building muscle tissue itself, intakes above 2.2 g/kg/day don’t appear to offer additional benefit.
How to Spread Protein Across the Day
Your body can only use so much protein at once for muscle repair. Research consistently points to 20 to 40 grams of protein per meal as the effective dose, with a more personalized target of about 0.4 to 0.55 g/kg per meal spread across four eating occasions. For most people, that means four meals of 25 to 50 grams each, spaced roughly three to four hours apart.
Younger adults appear to hit their muscle-building threshold at around 20 to 25 grams per sitting. Older adults typically need more per meal to get the same response, partly because aging muscles become less efficient at using dietary protein (a phenomenon researchers call anabolic resistance). A pre-sleep protein dose of 30 to 40 grams, particularly from slow-digesting sources like casein found in dairy, has been shown to increase overnight muscle protein synthesis and metabolic rate.
The “Anabolic Window” Is Overblown
You’ve probably heard you need to chug a protein shake within 30 minutes of your last set. A systematic review and meta-analysis published in Nutrients found that consuming protein anywhere from 15 minutes before exercise to about two hours after made no meaningful difference in lean body mass or upper-body strength. The timing of your protein matters far less than the total amount you eat over the course of a day.
There was a small signal that pre-workout protein might improve leg strength, but the evidence was based on only two studies and didn’t reach a strong level of statistical confidence. In short, if eating protein right after training fits your schedule, great. If it doesn’t, your muscles aren’t wasting away while you drive home and cook dinner.
Protein Quality: Animal vs. Plant Sources
A meta-analysis of randomized controlled trials found that protein source did not affect total lean mass or muscle strength gains when total protein intake was adequate. That said, animal protein showed a slight edge for percentage lean mass, particularly in adults under 50, where those eating animal protein gained an average of 0.41 kg more lean mass than plant-protein groups.
The key factor in protein quality is leucine content. Leucine is an amino acid that acts as a trigger for muscle protein synthesis. You need roughly 2 to 3 grams of leucine per meal to fully activate that process. Animal proteins like chicken, eggs, fish, and dairy naturally contain about 8 to 13% leucine by weight, so a 25-gram serving easily clears the threshold. Plant proteins like rice, pea, or soy tend to have lower leucine concentrations, which means you may need a slightly larger serving, around 30 to 40 grams, to get the same trigger effect. Combining different plant sources or simply eating a bit more total protein easily closes this gap.
Calorie Deficit vs. Surplus
Building muscle is easier when you’re eating more calories than you burn. A calorie surplus gives your body the energy it needs to synthesize new tissue. In this context, protein at the 1.6 to 2.2 g/kg range is generally sufficient.
If you’re trying to lose fat and gain muscle at the same time (body recomposition), protein becomes even more important. When calories are restricted, your body is more likely to break down muscle for energy unless protein intake is high enough to protect it. Most practitioners recommend pushing toward the upper end of the range, around 2.0 to 2.4 g/kg/day, during a calorie deficit. An eight-week trial in physically active middle-aged adults found that a moderate protein intake of about 1.0 g/kg/day was enough to maintain existing muscle mass, but not to build new tissue. To actually add muscle while losing fat, higher intakes combined with progressive resistance training are needed.
Protein Needs After 50
Aging muscles respond less efficiently to protein, which means older adults need to eat more of it to get the same muscle-preserving and muscle-building effect. The current recommended dietary allowance for protein doesn’t change with age, but researchers increasingly argue it should. Experts in geriatric nutrition recommend that older adults consume at least 1.0 to 1.2 g/kg/day just to maintain muscle mass, with higher intakes likely needed to build it.
Distribution matters more with age, too. Because each meal needs a higher protein dose to overcome anabolic resistance, older adults benefit from making sure every meal contains a meaningful portion of protein rather than loading it all into dinner, which is the pattern most people default to.
Is High Protein Safe?
For healthy people, high-protein diets are not known to cause medical problems. The concern about protein damaging kidneys comes from studies on people who already have kidney disease, where the extra waste products from protein breakdown can worsen kidney function. If your kidneys are healthy, intakes in the 1.6 to 2.2 g/kg range are well within safe limits.
The real risks of high-protein diets tend to come from what you eat alongside the protein, not the protein itself. Diets heavy in red and processed meats can raise LDL cholesterol and heart disease risk. Very restrictive high-protein diets that cut carbohydrates aggressively can lead to inadequate fiber intake, constipation, and headaches. Choosing a mix of lean meats, fish, dairy, legumes, and whole grains sidesteps most of these issues while still hitting your protein targets comfortably.