Most people need about 20 to 40 grams of protein after a workout, depending on body size. A more precise target is 0.25 to 0.31 grams of protein per kilogram of body weight (roughly 0.11 to 0.14 grams per pound). For someone weighing 180 pounds (82 kg), that works out to about 20 to 25 grams. For someone weighing 220 pounds (100 kg), it’s closer to 25 to 31 grams.
Why Body Weight Matters More Than a Flat Number
The widely cited “20 grams of protein” recommendation comes from dose-response studies conducted on men who weighed around 176 pounds (80 kg). That number works well for average-sized people, but it underestimates needs for larger individuals and overestimates for smaller ones. A breakpoint analysis published in Frontiers in Nutrition found that muscle-building rates plateau at about 0.31 grams of protein per kilogram of body weight per meal. When you factor in natural variation between individuals, an upper target of about 0.39 grams per kilogram covers most people comfortably.
Here’s what that looks like in practice:
- 130 lb (59 kg) person: 15 to 23 grams
- 160 lb (73 kg) person: 18 to 28 grams
- 180 lb (82 kg) person: 20 to 32 grams
- 220 lb (100 kg) person: 25 to 39 grams
What Happens if You Eat More Than That
Your body doesn’t waste excess protein. It just can’t use unlimited amounts for muscle repair in one sitting. There appears to be a ceiling for how much protein can actively stimulate muscle building at once, but protein eaten beyond that threshold still gets digested and absorbed normally. It sits in your gut longer, gets broken down at a slower rate, and the amino acids are used for other functions or converted to energy. You won’t harm yourself by eating 50 grams instead of 30, but the extra 20 grams won’t accelerate muscle growth from that particular meal.
Research on intermittent fasting supports this. People who consumed large amounts of protein in a compressed eating window showed no differences in lean mass compared to those spreading the same total across more meals. The key takeaway: hitting your daily protein target matters more than perfecting any single dose.
The Post-Workout Window Is More Flexible Than You Think
The idea that you need to chug a protein shake within 30 minutes of your last set has been largely overstated. Muscle protein synthesis stays elevated for at least 24 hours after resistance training, and some research shows it remains elevated for up to 48 hours. Getting protein soon after exercise is still a good habit, but delaying it by a couple of hours produces no measurable downside in most studies.
The one scenario where timing genuinely matters is training on an empty stomach. If you worked out first thing in the morning without eating, your muscles are more responsive to incoming protein and getting a meal or shake within an hour or two is more beneficial. If you ate a solid meal one to three hours before training, that food is still being digested and supplying amino acids during and after your session, which effectively removes the urgency.
Protein Needs Across Different Types of Exercise
Strength training creates more muscle damage than endurance exercise, so daily protein needs differ between the two. People who lift weights regularly need about 1.4 to 2.0 grams of protein per kilogram of body weight per day. Endurance athletes training more than 10 hours a week need slightly less, around 1.2 to 1.4 grams per kilogram per day. For context, someone who exercises casually needs about 1.1 to 1.5 grams per kilogram daily, compared to roughly 0.8 grams for sedentary adults.
The post-workout dose itself doesn’t change dramatically between training types. The 0.25 to 0.31 grams per kilogram guideline applies across the board. What changes is how much protein you need across the rest of the day to support recovery.
Protein Quality and Source
Not all protein sources trigger muscle repair equally. The amino acid leucine acts as a kind of ignition switch for muscle building, and you need roughly 2 to 3 grams of it in a meal to fully activate that process. Whey protein, eggs, and most animal proteins are naturally high in leucine, so a 20 to 25 gram serving typically delivers enough. Plant-based proteins like soy, pea, or rice tend to be lower in leucine and may have smaller amounts of certain essential amino acids.
The practical fix is straightforward: eat a larger serving of plant-based protein to compensate. If 25 grams of whey does the job, you may need 30 to 40 grams of a plant source to get a comparable amino acid profile. Blending different plant proteins (rice and pea, for instance) can also help fill in amino acid gaps.
Older Adults Need More, Not Less
After about age 60, muscles become less responsive to protein. This phenomenon, called anabolic resistance, means the same dose that works for a 25-year-old produces a weaker muscle-building response in an older adult. To compensate, experts recommend that healthy older adults consume at least 1.0 to 1.2 grams of protein per kilogram of body weight per day, and those with chronic illness may need 1.2 to 1.5 grams per kilogram or more.
For post-workout doses specifically, older adults benefit from aiming toward the higher end of the range, around 0.39 grams per kilogram per meal, and prioritizing leucine-rich protein sources. A 150-pound (68 kg) older adult, for example, would aim for roughly 27 grams of high-quality protein after training rather than the 17 to 21 grams that might suffice for a younger person of the same size.
Daily Total Trumps Post-Workout Timing
The single most important factor for muscle recovery and growth is total daily protein intake, not the exact amount you eat in any one sitting. If you consistently hit 1.4 to 2.0 grams per kilogram per day spread across three to four meals, your post-workout window is already covered. The post-workout shake is a convenient tool for people who struggle to eat enough protein through whole foods, but it’s not a magic accelerator. Consistently eating enough protein every day, from whatever sources fit your diet, is what drives results over weeks and months.