Most people need between 1.4 and 2.0 grams of protein per kilogram of body weight per day to build muscle. For a 180-pound (82 kg) person, that works out to roughly 115 to 164 grams of protein daily. The exact number depends on your age, training intensity, and whether you’re also trying to lose fat.
Daily Protein Targets by Goal
The International Society of Sports Nutrition recommends 1.4 to 2.0 grams per kilogram of body weight per day for people who exercise regularly and want to build or maintain muscle. Mayo Clinic narrows that slightly for people who lift weights or train for endurance events: 1.2 to 1.7 grams per kilogram. These ranges overlap enough to give you a reliable target.
Here’s what that looks like in real numbers for common body weights:
- 150 lbs (68 kg): 95–136 g of protein per day
- 180 lbs (82 kg): 115–164 g per day
- 210 lbs (95 kg): 133–190 g per day
If you’re trying to lose fat at the same time, you don’t need less protein. You likely need more. Keeping protein on the higher end of the range (closer to 2.0 g/kg) helps preserve the muscle you already have while your body is running on fewer calories. Cutting protein during a fat-loss phase is one of the fastest ways to lose muscle along with fat.
Why Spreading Protein Across Meals Matters
Your body can only use so much protein at once to build muscle. Research consistently shows that 20 to 40 grams of high-quality protein per meal is the effective range for triggering muscle growth. A landmark study found that a serving of beef providing 30 grams of protein was enough to maximally stimulate the muscle-building process, and eating more than that in a single sitting didn’t improve the response.
This means eating 10 grams of protein at breakfast, 15 at lunch, and dumping 65 grams into dinner (a pattern most people default to) is significantly less effective than spreading roughly 30 grams across each meal. One study comparing these two approaches found that evenly distributed protein stimulated 24-hour muscle protein synthesis to a greater extent, even when total daily protein was identical.
A practical rule: aim for 30 to 45 grams of protein at each of your three main meals, spaced about 3 to 4 hours apart. If you train in the evening, a 30 to 40 gram serving of slow-digesting protein (like cottage cheese or casein) before bed has been shown to increase overnight muscle protein synthesis without affecting fat metabolism.
The Leucine Connection
Not all protein triggers muscle growth equally, and the reason comes down to one specific amino acid: leucine. Your muscles essentially need a minimum dose of leucine to “switch on” the building process. That threshold sits around 2 to 3 grams of leucine per meal. Younger adults can hit it with about 20 grams of animal protein. Older adults typically need closer to 30 to 40 grams to cross the same threshold.
Animal proteins like eggs, chicken, fish, dairy, and beef are naturally rich in leucine. A chicken breast or a scoop of whey protein easily delivers 2 to 3 grams. Plant proteins tend to be lower in leucine, which is part of why they produce a weaker muscle-building signal gram for gram.
Adjustments for Age
If you’re over 50, your muscles become harder to stimulate with the same dose of protein. This phenomenon, sometimes called anabolic resistance, means your body needs a louder signal to trigger the same growth response. A 22-year-old might need only 0.2 grams of protein per kilogram per meal to maximize muscle building. A 70-year-old needs roughly double that: 0.4 grams per kilogram per meal. For a 165-pound person over 50, that translates to about 30 grams of protein per meal as a minimum.
Stanford Lifestyle Medicine recommends that adults over 50 aim for 1.2 to 1.6 grams per kilogram of body weight daily, which is roughly double the standard federal recommendation of 0.8 grams. The federal guideline was designed to prevent deficiency, not to support muscle growth, so it falls short for anyone actively trying to build or preserve muscle tissue.
Plant Protein vs. Animal Protein
You can absolutely build muscle on plant-based protein, but it requires more planning. Research published in The Journal of Nutrition confirms that soy and wheat protein produce a lower muscle-building response compared to animal sources like whey or beef. There are a few reasons for this. Plant proteins are generally less digestible, meaning fewer of the amino acids you eat actually reach your muscles. They’re also lower in leucine and other essential amino acids, so they’re less efficient at flipping that muscle-building switch.
The workaround is straightforward: eat more total protein if your sources are primarily plant-based. Combining different plant proteins (rice and beans, for example) helps fill in amino acid gaps. If you eat a fully plant-based diet and want to optimize muscle growth, aiming for the higher end of the protein range (closer to 2.0 g/kg) and prioritizing leucine-rich plant sources like soy, lentils, and peanuts will help close the gap with animal protein.
Can You Eat Too Much?
For healthy people, there’s no strong evidence that protein in the 1.4 to 2.0 g/kg range causes harm. Harvard Health suggests keeping intake below about 2.0 grams per kilogram of ideal body weight for the average healthy person who isn’t a competitive athlete. Beyond that, the returns for muscle building diminish and some risks start to appear.
Very high protein diets are associated with a higher risk of kidney stones. If your extra protein comes primarily from red meat and saturated fat, there’s also an elevated risk of heart disease and colon cancer over the long term. These risks aren’t about protein itself but about the food sources and the quantities involved. Hitting 1.6 g/kg from a mix of chicken, fish, eggs, dairy, and legumes is a very different health profile than hitting 3.0 g/kg from processed red meat.
Putting It All Together
For most people lifting weights and eating enough calories, the practical target is 1.6 grams of protein per kilogram of body weight per day. That sits comfortably in the middle of every major guideline and is enough to support muscle growth without overcomplicating your diet. Split that total across three to four meals, with each meal delivering at least 30 grams of protein. Prioritize protein sources rich in essential amino acids, and if you’re over 50 or eating mostly plants, nudge the numbers upward. The actual foods matter less than consistency: hitting your target day after day is what drives results.