Most people need 20 to 40 grams of protein after a workout to get the full muscle-building benefit of their training session. A more precise target is about 0.25 to 0.31 grams per kilogram of body weight (0.11 to 0.14 grams per pound). For a 180-pound person, that works out to roughly 20 to 25 grams. For someone closer to 220 pounds, it’s closer to 30 to 35 grams.
The Dose That Maximizes Muscle Repair
After resistance exercise, your muscles ramp up the process of rebuilding damaged fibers. Protein from food provides the raw material, specifically amino acids, to fuel that repair. Studies measuring muscle protein synthesis in young adults (averaging around 175 pounds) consistently find that 20 grams of a high-quality, fast-digesting protein like whey hits the point of diminishing returns. Beyond that amount, the extra amino acids are increasingly burned for energy rather than used to build muscle.
When researchers recalculated these findings relative to body weight, the sweet spot landed at about 0.31 grams per kilogram. Adding a 25% safety margin to account for individual variation pushes the upper useful limit to around 0.39 grams per kilogram. In practical terms, that means a 150-pound person tops out around 26 grams, while a 200-pound person could benefit from up to 35 grams.
There’s one important exception to the 20-gram baseline: whole-body workouts. Training multiple large muscle groups in a single session (think a full-body routine rather than an arm day) creates more total muscle damage. Evidence suggests that 40 grams of protein stimulates greater muscle repair than 20 grams after whole-body resistance training. If your sessions hit legs, back, and chest all at once, aim for the higher end of the range.
Timing Matters Less Than You Think
The idea of a narrow “anabolic window,” where you need to chug a protein shake within 30 minutes or lose your gains, has been a gym staple for decades. The research tells a different story. A recent meta-analysis of randomized controlled trials found that consuming protein anywhere from 15 minutes before exercise to about 2 hours after had no significant effect on strength gains or lean body mass compared to other timing strategies. The differences were essentially zero.
What does matter is that you eat protein at some point in the hours surrounding your workout. The muscle-building stimulus from a training session lasts at least 24 hours, though the effect is strongest in the first few hours and gradually fades. So while there’s no need to panic if you can’t eat immediately, getting a protein-rich meal or snack within a couple of hours after training is a reasonable habit. If you trained fasted first thing in the morning, eating sooner rather than later makes more sense than if you had a big lunch an hour before your session.
Your Daily Total Trumps Post-Workout Timing
Here’s what the research consistently points to: if you’re already hitting adequate daily protein, the timing of your post-workout dose has a modest effect at best. People consuming at least 1.6 grams of protein per kilogram of body weight per day (about 0.73 grams per pound) may not see added benefit from precisely timing their post-training protein. For a 170-pound person, that daily target is roughly 124 grams spread across all meals and snacks.
This means the single most impactful thing you can do is make sure your total daily intake is high enough. Distributing that protein across 3 to 5 meals, with each meal containing at least 20 to 40 grams, gives your body repeated opportunities to stimulate muscle repair throughout the day. One of those meals happening near your workout is ideal, but obsessing over the exact minute matters far less than consistency with your overall diet.
Endurance vs. Strength Training
If your workout is a long run, bike ride, or swim rather than a lifting session, your protein needs after exercise shift slightly. Prolonged endurance exercise (longer than about 2 hours) burns through significant amounts of amino acids, particularly leucine, which is the key amino acid that triggers muscle repair. Intense endurance sessions also cause some intestinal stress that can affect nutrient absorption. The result is that endurance athletes often end up in a negative protein balance without deliberate attention to recovery nutrition.
Post-workout protein for endurance athletes serves a broader purpose than just muscle repair. It helps reduce muscle breakdown, supports immune function (intense training temporarily suppresses the immune system), and contributes to adaptations in the energy-producing systems of muscle cells. The 20 to 40 gram range still applies, but pairing protein with carbohydrates becomes more important after endurance work, since glycogen replenishment is a priority that strength athletes don’t face to the same degree.
Adjustments for Older Adults
As you age, your muscles become less responsive to the signal that protein sends to trigger repair, a phenomenon called anabolic resistance. A 22-year-old might need only 0.2 grams per kilogram per meal to get a strong muscle-building response, while a 70-year-old needs roughly double that, around 0.4 grams per kilogram. In absolute terms, adults over 50 should aim for 30 to 35 grams of protein per meal, and especially after strength training sessions.
The amino acid leucine plays a central role here. Younger adults can trigger robust muscle repair with about 2 grams of leucine per meal (the amount in roughly 20 grams of whey protein), but older adults likely need closer to 3 grams. Choosing protein sources that are naturally rich in leucine, such as dairy, eggs, chicken, and fish, helps close that gap without needing to eat dramatically more food.
Plant-Based Protein Works With One Caveat
If you’re using plant-based protein, the good news is that studies show plant and whey protein powders are equally effective at promoting muscle growth, provided they deliver similar amounts of protein and essential amino acids per serving. The key is leucine content. A good protein source, plant or animal, should provide at least 1 to 3 grams of leucine per serving along with 20 to 30 grams of total protein.
Single-source plant proteins (rice alone, or pea alone) can fall short on one or more essential amino acids. Blended plant protein powders that combine two or more sources, like pea and rice, typically have a more complete amino acid profile. If you rely on whole foods rather than powders, combining legumes with grains at your post-workout meal achieves the same effect. You don’t need to eat more total protein just because it’s plant-based, but you do need to pay attention to variety and leucine content.
What This Looks Like in Real Food
Twenty to 40 grams of protein doesn’t require a supplement. Here’s roughly what 25 to 30 grams looks like from common foods:
- Greek yogurt: one cup (about 250 grams) delivers 15 to 20 grams, so pair it with a handful of nuts or some granola to round out the target
- Chicken breast: a palm-sized portion (about 100 grams cooked) provides roughly 30 grams
- Eggs: four large eggs give you about 24 grams
- Canned tuna: one standard can (about 140 grams drained) contains roughly 30 grams
- Whey protein shake: one typical scoop delivers 20 to 25 grams
- Cottage cheese: one cup provides about 25 grams
If you’re cutting calories, protein becomes even more important. Resistance-trained individuals in a caloric deficit may need as much as 2.3 to 3.1 grams per kilogram of fat-free mass daily to prevent muscle loss. That’s substantially higher than the standard recommendation, making it worth planning each meal around a protein source rather than treating it as an afterthought.