Most people need 20 to 40 grams of protein after a workout to fully support muscle repair. The exact amount depends on your body size and age, but for an average-sized adult around 80 kg (175 lbs), 20 grams of high-quality protein is enough to maximize the muscle-building response. Larger individuals and older adults benefit from more.
The 20-to-40-Gram Window
When you finish resistance training, your muscles are primed to absorb amino acids and start rebuilding damaged fibers. Studies consistently show that consuming about 20 grams of protein after exercise maximizes the rate of muscle protein synthesis in young adults of average size. Going above that amount doesn’t meaningfully boost the repair process. One well-known study found that a 30-gram serving of beef protein fully stimulated muscle protein synthesis, and a larger serving produced no additional benefit.
That said, 20 grams is an average, not a universal number. A more personalized approach uses body weight: aim for roughly 0.31 grams of protein per kilogram of body weight after training. To account for natural person-to-person variation, researchers suggest an upper target of about 0.39 g/kg. For a 70 kg (154 lb) person, that works out to roughly 22 to 27 grams. For a 90 kg (200 lb) person, it’s closer to 28 to 35 grams.
Why Body Size Matters
Flat recommendations like “eat 20 grams” were developed from studies of men who averaged about 80 kg. If you weigh significantly more, you have more muscle tissue to repair and will likely benefit from a larger dose. Research on meal frequency and lean mass found that regularly consuming 30 to 45 grams of protein per meal was most strongly associated with greater leg lean mass and strength. If you’re a larger or more muscular person, landing in that 30-to-45-gram range after training is a reasonable target.
Older Adults Need More
If you’re over 60, your muscles don’t respond to protein as efficiently as they once did. This phenomenon, called anabolic resistance, means the same 20-gram dose that works well for a 25-year-old produces a weaker muscle-building signal in an older adult. Research from the Gatorade Sports Science Institute shows that 35 to 40 grams of high-quality protein after exercise produces significantly greater muscle repair rates in older men compared to 20 grams.
For active older adults, the practical target is 30 to 40 grams of protein immediately after exercise, with similar-sized servings at each main meal throughout the day. This higher per-meal threshold helps overcome the blunted response and better supports muscle maintenance over time.
Protein Quality Counts
Not all protein sources trigger muscle repair equally. The key factor is leucine, an amino acid that acts as the on-switch for your body’s muscle-building machinery. You need roughly 2.5 to 3 grams of leucine in a meal to fully activate that process. Whey protein, eggs, chicken, fish, and lean beef are all leucine-rich options that hit that threshold in a normal serving. Plant proteins like beans, lentils, and rice tend to be lower in leucine per gram, so you may need a larger portion or a combination of sources to reach the same trigger point.
A scoop of whey protein (typically 25 to 30 grams) delivers around 2.5 to 3 grams of leucine, which is why it shows up so often in the research. But whole foods work just fine. A chicken breast, a few eggs, Greek yogurt, or a can of tuna will get you there.
Timing Is Less Important Than You Think
The idea of a narrow “anabolic window” closing 30 minutes after your last set has been largely overstated. Consuming protein within about two hours of exercise supports muscle repair, and Mass General Brigham recommends at least 15 to 25 grams within that timeframe. But the most important factor by far is your total daily protein intake, not the precise minute you eat after training.
Sports nutrition experts broadly agree that hitting 1.6 to 2.2 grams of protein per kilogram of body weight per day is what drives long-term muscle growth. For a 75 kg (165 lb) person, that’s 120 to 165 grams spread across the day. If you consistently reach that daily target, the exact timing of your post-workout meal matters much less. Distributing your intake evenly across three or four meals, each containing 30 or more grams, is a simple and effective strategy.
Quick Reference by Body Weight
- 60 kg (132 lbs): 19 to 23 g post-workout; 96 to 132 g daily
- 75 kg (165 lbs): 23 to 29 g post-workout; 120 to 165 g daily
- 90 kg (200 lbs): 28 to 35 g post-workout; 144 to 198 g daily
- 100 kg (220 lbs): 31 to 39 g post-workout; 160 to 220 g daily
- Adults over 60 (any weight): 30 to 40 g post-workout; aim for 30+ g at every meal
Going Over 40 Grams Isn’t Harmful
If you eat a large meal after the gym and end up with 50 or 60 grams of protein, you’re not wasting it. Your body still digests and absorbs all of it. The excess amino acids beyond what your muscles can use for repair get used for other functions: enzyme production, immune support, or simply converted into energy. You won’t build more muscle from that single meal than you would from 30 to 40 grams, but the protein doesn’t disappear. It’s just not doing extra muscle-building work in that moment.
What this means practically is that there’s no reason to stress about hitting an exact number. Eating a solid meal with a palm-sized portion of protein-rich food after training puts most people right in the effective range. The bigger priority is making sure your total intake across the day consistently lands in the 1.6 to 2.2 g/kg range, meal after meal, day after day.