Most people benefit from 20 to 40 grams of protein after a workout, with the more precise target being about 0.25 to 0.40 grams per kilogram of body weight. For a 180-pound (82 kg) person, that works out to roughly 20 to 33 grams. But the full picture is more nuanced than a single number, and the total protein you eat across the day matters at least as much as what you eat right after training.
The Per-Meal Target
The most comprehensive analysis of protein and muscle building found that 0.4 g/kg per meal, spread across at least four meals a day, optimally stimulates muscle repair and growth. At the upper end, 0.55 g/kg per meal is the highest useful dose supported by research. Here’s what that looks like at different body weights:
- 140 lbs (64 kg): 25–35 g per meal
- 180 lbs (82 kg): 33–45 g per meal
- 220 lbs (100 kg): 40–55 g per meal
The often-cited “20 to 25 grams” recommendation comes from studies on younger adults, and it holds up well for people under about 160 pounds. Larger individuals need more. If you’ve been defaulting to one scoop of protein powder (typically 20–25 g) regardless of your size, you may be leaving some benefit on the table.
Why These Numbers Work
Your muscles respond to a specific amino acid signal. The amino acid leucine acts as a trigger: once you consume enough of it in a single sitting, your body ramps up muscle protein synthesis. That threshold sits at roughly 3 to 4 grams of leucine, which corresponds to about 25 to 30 grams of a high-quality protein like whey, eggs, or meat. Eating below this threshold produces a weaker muscle-building response. Eating well above it doesn’t proportionally increase the response, though the extra protein still gets used for other bodily functions rather than being “wasted.”
The Anabolic Window Is Wider Than You Think
The old advice was to chug a protein shake within 30 to 45 minutes of your last set or miss out on gains. That urgency is largely overstated. The post-exercise window where your muscles are primed to use protein can stretch to five or six hours after training, depending on when you last ate before your workout.
If you had a solid meal containing protein one to two hours before training, that food is still being digested and delivering amino acids into your bloodstream during and after your session. In that scenario, rushing to consume protein immediately after is redundant. A study comparing pre-workout versus post-workout protein intake over 10 weeks found no significant difference in muscle or strength gains between the two groups, even when the pre-workout group waited at least three hours after training to eat again.
The practical guideline: your pre- and post-workout protein feedings shouldn’t be separated by more than about three to four hours, assuming a typical 45- to 90-minute training session. If you train fasted or haven’t eaten in four-plus hours, getting protein soon after your workout becomes more important.
Daily Protein Matters More Than Timing
The total amount of protein you eat each day has a bigger impact on muscle growth and recovery than precisely when you eat it. The major sports nutrition organizations recommend 1.2 to 2.0 g/kg per day for active adults. The sweet spot for maximizing muscle and strength gains from resistance training is around 1.6 g/kg per day. For a 180-pound person, that’s about 131 grams spread across the day.
Some situations push requirements higher. Endurance athletes doing intense training may need around 1.8 g/kg per day. If you’re in a calorie deficit trying to lose fat while preserving muscle, research suggests going as high as 2.3 to 3.1 g/kg of fat-free mass. That’s a meaningful jump, and it’s the main reason cutting phases feel so protein-heavy.
Not All Protein Sources Are Equal
Protein quality varies, and it matters for your post-workout choice. Whey protein has the highest biological value of common sources (104), meaning your body retains and uses a very high percentage of it. Eggs score 100, milk 91, beef 80, casein 77, and soy 74. Wheat gluten trails at 64.
Speed of absorption also differs. Whey delivers amino acids into your bloodstream quickly, producing a fast, sharp spike. Casein forms a gel-like clot in your stomach and releases amino acids slowly over several hours. This makes whey a better choice when you want rapid delivery (training fasted, for instance) and casein useful before long gaps between meals or overnight.
An interesting nuance: whey triggers a faster burst of muscle protein synthesis, but a larger portion of it gets burned as fuel. Casein produces a more sustained effect that may result in greater total protein retention over time. For most people, the practical takeaway is simple: whey or a whole-food protein source after training, and don’t stress about it beyond that.
Pairing Protein With Carbohydrates
If you do endurance training or long, glycogen-depleting sessions, combining protein with carbohydrates in a 3:1 or 4:1 carb-to-protein ratio enhances glycogen replenishment. In practice, that means about 1.2 to 1.5 g/kg of simple carbohydrates paired with 0.3 to 0.5 g/kg of protein within 30 minutes of finishing. For a 180-pound person, that’s roughly 100 to 120 grams of carbs with 25 to 40 grams of protein.
For pure strength training, glycogen replenishment is less urgent (you’ll refill stores by your next session regardless), and carbs don’t appear to boost the muscle protein synthesis response on their own. They still provide energy and support recovery, but the ratio matters less. Focus on hitting your protein target first.
Adjustments for Age
Adults over 60 experience what researchers call anabolic resistance: their muscles respond less strongly to the same amount of protein that works well for younger people. Overcoming this requires hitting the upper end of per-meal recommendations, around 25 to 30 grams of high-quality protein per meal, with an emphasis on leucine-rich sources. Many older adults fall short of this at breakfast and lunch, eating most of their protein at dinner. Distributing protein more evenly across meals, with at least 25 grams each time, produces a meaningfully better muscle-building stimulus at any age over 60.