Ask ten lifters how much protein you need per day and you'll get ten different answers. Some swear by "a gram per pound." Others stick to the federal RDA of 0.8 grams per kilogram and call anything above that a marketing scheme. Most people land somewhere in the middle, guessing.
The science actually has a pretty tight answer — and it's neither extreme. In the last decade, several large meta-analyses have run the numbers across hundreds of studies and thousands of participants, and the curves they produce converge on a surprisingly narrow range. We pulled the highest-quality reviews from British Journal of Sports Medicine, the Journal of the International Society of Sports Nutrition, and Sports Medicine to figure out where that range lands, why total daily intake matters more than people think, and whether the source of your protein (whey vs. plant) actually changes the result.
If you train hard, eat in deficit sometimes, or just want to stop wondering whether your shake is doing anything, this is the guide we wish more people would just send each other.
The RDA is a floor, not a target
The Recommended Dietary Allowance for protein, set by the Institute of Medicine, is 0.8 grams per kilogram of body weight per day.[1] That number gets tossed around like it's the answer, but it's not. The RDA is the amount needed to prevent deficiency in 97.5% of healthy sedentary adults — the bare minimum to keep nitrogen balance from going negative.
The Acceptable Macronutrient Distribution Range (AMDR) is much wider: 10–35% of total daily calories.[1] That's a hint that the floor and the optimum are not the same number. If you lift, run, cycle, or do anything that breaks down muscle tissue, you need more protein to rebuild it — and "more" has been quantified.
What the meta-analyses converge on: roughly 1.6 g/kg/day
The most-cited number in modern sports nutrition is 1.6 grams per kilogram of body weight per day. It's not arbitrary. It's the point where, across 49 randomized controlled trials and 1,863 participants, additional protein stopped producing additional muscle.
In a 2018 meta-analysis published in the British Journal of Sports Medicine, Morton and colleagues found that protein supplementation significantly increased one-rep max strength (+2.49 kg), fat-free mass (+0.30 kg), and muscle fiber cross-sectional area when combined with resistance training.[2] But the effect plateaued: "Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further RET-induced gains in FFM."[2]
A 2022 dose-response meta-analysis in Sports Medicine - Open by Tagawa et al. ran the math a different way — fitting spline curves to data from 82 RCTs — and arrived at a similar conclusion: muscle strength rose by 0.72% per 0.1 g/kg/day of additional protein intake, with the curve flattening at approximately 1.5 g/kg/day.[3] Critically, that same study found no benefit from extra protein in the absence of resistance training. Protein is a multiplier on the work you put in, not a substitute for it.[3]
The International Society of Sports Nutrition's position stand on protein and exercise — written by 21 researchers and published in the Journal of the International Society of Sports Nutrition — places the practical range slightly wider: 1.4–2.0 g/kg/day "for building muscle mass and maintaining muscle mass through a positive muscle protein balance."[4] If you're dieting and trying to hold onto lean tissue, the ISSN suggests bumping that to 2.3–3.1 g/kg/day during periods of caloric deficit.[4]
How much per meal — and how often
Total daily protein matters most, but the way you split it across the day also matters, especially if you're trying to maximize muscle protein synthesis (MPS).
Acute studies show that a single dose of fast-digesting protein roughly 0.25 g/kg — or about 20–40 grams in absolute terms — maximally stimulates MPS in young adults.[4] Above that, additional protein in a single meal is either oxidized for fuel or used for other metabolic purposes, with diminishing returns on muscle building.[5]
In a 2018 review, Schoenfeld and Aragon proposed a practical heuristic that's now widely cited: consume around 0.4 g/kg of protein per meal across at least four meals to comfortably hit a daily target of 1.6 g/kg.[5] If you're at the upper end of the ISSN range (2.2 g/kg), that becomes roughly 0.55 g/kg per meal. The ISSN's own recommendation: evenly distribute doses every 3–4 hours.[4]
Here's what that looks like in practice for a few common body weights:
| Body weight | Daily target (1.6 g/kg) | Per meal (4 meals) | Upper range (2.0 g/kg) |
|---|---|---|---|
| 140 lb (64 kg) | ~102 g | ~26 g | ~127 g |
| 170 lb (77 kg) | ~123 g | ~31 g | ~154 g |
| 200 lb (91 kg) | ~146 g | ~36 g | ~182 g |
| 230 lb (104 kg) | ~167 g | ~42 g | ~209 g |
That table is also why a protein shake is more than just a "convenience" item — for a 200-lb lifter aiming at 36 grams per meal, missing one feeding window leaves a real hole in the day's total. A scoop of our Whey Protein Isolate delivers about 25 grams per serving, which closes that gap in 30 seconds.
Whey vs. plant: does the source matter?
This is where conventional wisdom is actively being rewritten. For years, the assumption was that animal-derived proteins (whey, casein, eggs) were meaningfully better than plant proteins for building muscle, because they're "complete" — they contain all essential amino acids in higher proportions, with more leucine per gram.
The acute MPS data still supports that on a per-gram basis. But when researchers run longer-term studies and equalize total protein intake, the gap mostly vanishes.
A 2021 trial published in Sports Medicine compared habitual vegans and omnivores on a 12-week supervised resistance training program. Both groups consumed 1.6 g/kg/day of protein — vegans via plant foods plus soy protein isolate, omnivores via mixed foods plus whey. Leg lean mass, muscle cross-sectional area, fiber type I and type II area, and leg-press 1RM all increased significantly in both groups, with no between-group differences.[6] The authors concluded that "protein source does not affect resistance training-induced adaptations in untrained young men consuming adequate amounts of protein."[6]
A 2020 randomized trial in International Journal of Environmental Research and Public Health compared soy and whey supplements matched for leucine content (2 g per serving) across 12 weeks of training. Total body mass, lean body mass, and peak torque all rose in both groups, with no statistically significant difference between them.[7]
The takeaway: if you hit your total protein target and your plant source has a reasonable leucine content, you're not leaving meaningful gains on the table. Our Plant Protein (Chocolate) is built around that finding — designed to deliver a leucine-balanced dose per serving so dairy-free lifters don't have to compromise.
Common mistakes we see
Most of the people who write to us about protein aren't underdosing by a little — they're either overshooting it (sometimes by 100%) or scattering it badly across the day.
Mistake one: assuming more is always better. The plateau in the Morton meta-analysis is real.[2] Going from 1.6 to 2.5 g/kg/day costs more, takes up calorie budget that could go to carbs or fat, and doesn't produce meaningfully more muscle in trained lifters. (Hypocaloric dieting is a separate case — see the ISSN range above.[4])
Mistake two: back-loading protein. Two meals — a chicken-and-rice lunch and a steak dinner — can technically hit your daily total but leave 16+ hours where MPS isn't being stimulated. Spread the load.[5]
Mistake three: assuming you can't train hard without animal protein. The data doesn't support that.[6,7] Hit the total, watch the leucine, and the body responds.
Frequently asked questions
Is 1 gram of protein per pound of body weight too much?
For most people, yes — slightly. "1 gram per pound" works out to about 2.2 g/kg/day, which is above the muscle-building plateau identified in current meta-analyses.[2,3] It's not harmful for healthy adults, but it's also not producing additional gains for most lifters. The exception is people in a caloric deficit, where the ISSN suggests 2.3–3.1 g/kg/day to preserve lean mass.[4]
Can I get all my protein from whole food and skip supplements?
Yes. The ISSN explicitly states that supplementation is "a practical way of ensuring intake of adequate protein quality and quantity" but is not required.[4] Powder is mainly a convenience tool — it helps when a meal would otherwise be carb-only or skipped.
How much protein per meal is too much?
There isn't a hard cutoff. Above roughly 20–40 grams of fast-digesting protein, additional amino acids are increasingly oxidized rather than used for muscle building, but they're not wasted in a harmful way.[5] Practically: aim for ~0.4 g/kg per meal across four meals as a starting point.[5]
Does protein timing around workouts matter?
The "anabolic window" is wider than the old 30-minute rule suggested. The ISSN's position is that pre- or post-workout protein both work, and the anabolic effect of training lasts at least 24 hours.[4] Hitting your daily total matters more than the exact clock.
Is plant protein really equal to whey if I'm older?
The matched-intake trials so far have been in younger adults.[6,7] Older adults experience "anabolic resistance" — reduced muscle sensitivity to protein — and the ISSN suggests they may need a higher relative leucine content to overcome it.[8] If you're over 60 and using a plant-only stack, pay extra attention to leucine per serving.
The bottom line
If you train, target roughly 1.6 grams of protein per kilogram of body weight per day, spread across 3–5 meals of ~0.4 g/kg each. Source matters less than total — pick whichever protein (whey, plant, mixed) lets you actually hit the number consistently. If you're cutting, push higher (1.8–2.2 g/kg). If you're not training, the meta-analyses say extra protein won't do much.[3]
Whether you build it from chicken, lentils, or a shake, the numbers are the numbers. Hit them, lift, and the work pays off.
References
- Office of Dietary Supplements, National Institutes of Health. (n.d.). Dietary Supplements for Exercise and Athletic Performance — Health Professional Fact Sheet. View source
- Morton, RW, Murphy, KT, McKellar, SR, Schoenfeld, BJ, Henselmans, M, Helms, E, Aragon, AA, Devries, MC, Banfield, L, Krieger, JW, Phillips, SM. (2018). 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. British Journal of Sports Medicine, 52(6), 376-384. View source
- Tagawa, R, Watanabe, D, Ito, K, Otsuyama, T, Nakayama, K, Sanbongi, C, Miyachi, M. (2022). Synergistic Effect of Increased Total Protein Intake and Strength Training on Muscle Strength: A Dose-Response Meta-analysis of Randomized Controlled Trials. Sports Medicine - Open, 8(1), 110. View source
- Jäger, R, Kerksick, CM, Campbell, BI, et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14, 20. View source
- Schoenfeld, BJ, Aragon, AA. (2018). How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. Journal of the International Society of Sports Nutrition, 15, 10. View source
- Hevia-Larraín, V, Gualano, B, Longobardi, I, et al. (2021). High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores. Sports Medicine, 51(6), 1317-1330. View source
- Lynch, HM, Buman, MP, Dickinson, JM, Ransdell, LB, Johnston, CS, Wharton, CM. (2020). No Significant Differences in Muscle Growth and Strength Development When Consuming Soy and Whey Protein Supplements Matched for Leucine Following a 12 Week Resistance Training Program in Men and Women: A Randomized Trial. International Journal of Environmental Research and Public Health, 17(11), 3871. View source
- Ferrando, AA, Wolfe, RR, Hirsch, KR, et al. (2023). International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance. Journal of the International Society of Sports Nutrition, 20(1), 2263409. View source
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