How much protein do you actually need?
Not the number on the tub. The number the meta-analyses point to, for your bodyweight, your goal, and how much you train.
What protein actually does
Muscle is in constant turnover, built up and broken down all day. Training tilts that balance toward building; protein supplies the bricks. Eat too little and you can't rebuild faster than you break down, so the work you put in at the gym leaks away. That's the whole story for hypertrophy.
It does two other useful things while it's at it: protein is the most filling macronutrient per calorie (handy in a deficit), and it costs you roughly 20–30% of its own calories just to digest, the biggest "thermic effect" of the three macros. Neither is magic, but in a cut they add up.
How much, and where the numbers come from
Two big pieces of evidence anchor this:
- Morton's 2018 meta-analysis pooled 49 studies and found gains from extra protein plateau at roughly 1.6 g per kg of bodyweight per day. Eating more than that didn't add muscle. (Eating up to about 2.2 g/kg is fine; it's just not more effective. The wide confidence interval, 1.0–2.2 g/kg, is why we show a range.)
- Helms' 2014 review looked at lean, trained athletes in a calorie deficit (where protecting muscle matters most) and landed on 2.3–3.1 g per kg of fat-free mass, scaling up the leaner you get and the steeper the deficit.
So if you're building muscle and training regularly, aim for 1.6–2.2 g/kg. Cutting and trying to keep what you've got: 2.3–3.1 g/kg of lean mass (or about 2.0–2.5 g/kg of bodyweight if you don't know your body fat). Maintaining and training a bit: 1.6–2.0 g/kg. Not training? General health needs are lower, around 1.2–1.6 g/kg.
Spread it out. Schoenfeld & Aragon's 2018 review recommends roughly 0.4 g/kg per meal across at least four meals to keep muscle protein synthesis ticking over. That arithmetic, conveniently, lands you right at about 1.6 g/kg for the day. The calculator gives you a per-meal figure too.
Things you've heard that aren't true
"High protein wrecks your kidneys."
In people with healthy kidneys, no. A 2018 meta-analysis found higher-protein diets had no adverse effect on renal function. (If you have existing kidney disease, that's a real conversation to have with your doctor; see the note at the bottom.)
"You can only absorb 30 g of protein per meal."
You absorb essentially all of it. What's true is that there's a per-meal ceiling on how much you can use to build muscle in one sitting. That's exactly why spreading protein across the day beats one giant hit.
"Protein timing (the anabolic window) is everything."
Total daily intake does the heavy lifting. Getting protein within a few hours either side of training is a sensible default, but it's a rounding error next to hitting your daily number.
The science
Every number on this page traces back to one of these. No "studies show", no vibes.
References
- Morton RW, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376–384. PubMed
- Helms ER, et al. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab. 2014;24(2):127–138. PubMed
- Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr. 2018;15:10. PubMed
- Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. PubMed
- Devries MC, et al. Changes in Kidney Function Do Not Differ between Healthy Adults Consuming Higher- Compared with Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis. J Nutr. 2018;148(11):1760–1769. PubMed
- Phillips SM, Van Loon LJC. Dietary protein for athletes: from requirements to optimal adaptation. J Sports Sci. 2011;29 Suppl 1:S29–S38. PubMed
Knowing your protein number is the easy part. uppr handles the hard part. It programmes your training, picks your weights, manages your RIR week to week, and adapts when life gets in the way.
General educational information, not medical or dietary advice. If you have kidney disease, are pregnant, or have any condition affecting how you process protein, talk to a doctor or registered dietitian before changing your intake.