Protein: how much per day, which sources, and whether powder is worth it

Protein is the one supplement question where the research settled the argument. This page replaces the old “Food for Fitness” post on this site, which recommended lean meat and a balanced diet and never gave a protein number. The numbers below come from the trials and reviews published since, and the prices were checked on 09/28/2026.

How much protein per day do you need?

The Nutrition Facts label uses a Daily Value of 50 g of protein, the FDA’s general reference amount for food labels. It is not a target for people who lift, and it is far below what the muscle-gain literature supports.

The most useful single study for lifters is Morton and colleagues’ 2018 meta-analysis in the British Journal of Sports Medicine. It pooled 49 randomized trials with 1,863 participants who did resistance training for at least six weeks with or without added protein. Protein supplementation increased one-rep-max strength by an average of 2.49 kg and fat-free mass by 0.30 kg. The part that matters for your grocery list is the break-point analysis: once total daily protein reached about 1.62 g per kg of body weight, adding more produced no further gain in fat-free mass. The authors also found the supplement effect was larger in trained lifters and smaller with increasing age.

So the working numbers are:

Situation	Daily target	80 kg (176 lb) example
General population, FDA label Daily Value	50 g total	50 g
Lifting, maintenance or bulk	1.6 g/kg (plateau in Morton 2018)	128 g
Lifting, Morton 2018 upper confidence limit (the authors’ suggested target to maximize gains)	2.2 g/kg	176 g
Lifting in a calorie deficit	2.3 to 3.1 g per kg of fat-free mass (Helms 2014)	147 to 198 g at 20% body fat
ISSN general range for exercising people	1.4 to 2.0 g/kg	112 to 160 g

The International Society of Sports Nutrition’s 2017 position stand lands in the same place: 1.4 to 2.0 g/kg/day is “sufficient for most exercising individuals,” with 2.3 to 3.1 g/kg/day reserved for resistance-trained people trying to hold muscle while dieting. The ISSN also notes early evidence that intakes above 3.0 g/kg/day may help body composition in trained lifters, but that is a smaller and newer body of work than the 1.6 g/kg plateau.

Why does 2.2 g/kg get repeated if 1.6 is the plateau? Morton’s own 95% confidence interval for the plateau runs from 1.03 to 2.20 g/kg, so the authors suggest about 2.2 g/kg for anyone trying to maximize gains. It just costs more, which is what the table further down is for.

Why the target goes up when you cut

Helms and colleagues reviewed the six studies they found of lean, resistance-trained athletes eating in a calorie deficit. Six of the 13 study groups kept their fat-free mass; the only one of those that was lean, cutting hard and not starting a new training program was also the group eating the most protein in the review: 2.5 to 2.6 g per kg. Their recommendation is 2.3 to 3.1 g per kg of fat-free mass, “scaled upwards with severity of caloric restriction and leanness.”

Note that this is per kg of fat-free mass, not body weight. At 80 kg and 20% body fat, fat-free mass is 64 kg, so the range is about 147 to 198 g per day. If you do not know your body fat, using total body weight at 2.2 g/kg gets you close enough for most people who are not stepping on a bodybuilding stage.

How to split protein across the day

The old rule that the body “can only absorb 30 g at a time” confuses absorption with the muscle-building signal. Schoenfeld and Aragon worked through the data in 2018 and concluded the practical target is about 0.4 g/kg per meal across a minimum of four meals, which gets you to 1.6 g/kg/day. If you are aiming for 2.2 g/kg, the same four meals need about 0.55 g/kg each.

The ISSN’s stand gives the same shape: 0.25 g of high-quality protein per kg, or an absolute 20 to 40 g per feeding, evenly spaced every 3 to 4 hours, with each dose carrying 700 to 3,000 mg of leucine. It also names one specific bedtime tactic: 30 to 40 g of casein before sleep raises overnight muscle protein synthesis.

For the 80 kg example, that is 32 to 44 g at breakfast, lunch, dinner and one more feeding (a shake, cottage cheese, or casein before bed). Timing around the workout matters less than people think: the ISSN describes the anabolic effect of exercise as lasting at least 24 hours, so the daily total and the spacing beat any 30-minute window.

Whey vs plant vs collagen

Not all protein grams count the same for muscle. The ISSN is direct about the mechanism: it is the essential amino acids, leucine in particular, that stimulate muscle protein synthesis, and “rapidly digested proteins that contain high proportions of essential amino acids and adequate leucine are most effective.”

Source	Muscle-building evidence	Practical note
Whey isolate	Strongest per-gram response; high leucine, fast digestion	The default powder; isolates are near lactose-free
Casein	The other milk protein: complete, slightly less leucine than whey (9.3% vs 11% per the ISSN), slower digestion	ISSN names 30 to 40 g pre-sleep as a specific use
Soy, pea and other plant proteins	Lower response per gram in the studies done so far (mostly soy and wheat)	Proposed workarounds: a bigger dose, a blend, or a leucine-fortified product (untested for muscle protein synthesis as of the 2015 review)
Collagen peptides	Did not raise longer-term muscle protein synthesis above baseline in a head-to-head trial; whey did	Do not count it toward your muscle target

Whey is the benchmark because it is what most of the trials used. Casein is the other milk protein: complete, a little lower in leucine than whey (9.3% vs 11%, per the ISSN), and digested slowly because it coagulates in the gut.

Plant proteins are a weaker option per gram, with proposed workarounds. Van Vliet, Burd and van Loon reviewed the evidence in 2015 and found soy and wheat proteins produced a lower muscle protein synthetic response than several animal proteins, which they attribute to lower digestibility, more of the amino acids being pulled out by the gut and liver, and most plant proteins having relatively low leucine. They list four strategies that could close the gap, while noting that none had yet been tested for muscle protein synthesis: fortify with methionine, lysine or leucine; breed better crops; eat a larger dose; or blend sources so the amino acid profile balances out. If you use a plant powder, a pea-and-rice blend or a leucine-fortified product with a slightly larger scoop is the sensible move.

Collagen is the one to be careful with, because it is sold next to whey and priced like it. In Oikawa and colleagues’ 2020 randomized trial, healthy older women took 30 g of either whey or collagen peptides twice a day for six days with resistance exercise on one leg. Whey raised both acute and longer-term muscle protein synthesis; collagen raised acute synthesis only in the exercised leg, by less than whey, and did not raise longer-term synthesis significantly above baseline. Collagen’s amino acid profile is dominated by glycine, proline and hydroxyproline (Transparent Labs’ own product page names those three), the opposite of the leucine-rich essential amino acid mix the ISSN says drives muscle protein synthesis. Transparent Labs’ collagen page calls collagen peptides “complete protein sources”; the trial above is why this site does not treat them that way for muscle. Collagen for joints or skin is a separate question this page does not cover, and it belongs on top of your protein target, not inside it.

Is protein powder worth it? Cost per 20 g of protein

Here is the math that answers the question for most people. Food prices are the U.S. Bureau of Labor Statistics city-average retail prices for August 2026 (the latest month published on 09/28/2026). Protein content per food is from USDA FoodData Central. Powder prices are what each merchant’s product page showed on 09/28/2026.

Source	Price checked 09/28/2026	Protein in the package	Cost per 20 g protein
Eggs, grade A large	$2.27 per dozen (BLS)	75.6 g (12 eggs at 50 g, 12.6 g per 100 g)	$0.60
Whole milk	$4.23 per gallon (BLS)	about 127 g (3.27 g per 100 g, 3,900 g per gallon)	$0.66
Chicken breast, boneless, raw	$4.17 per lb (BLS)	102 g (22.5 g per 100 g)	$0.82
Transparent Labs Grass-Fed Whey Isolate, 2 lb	$64.99 ($58.49 on 10%-off subscription)	840 g (30 servings x 28 g)	$1.55 ($1.39 subscribed)
Legion Whey+, 30 servings	$69.99 one-time; $48.99 first subscription order (30% off), then $59.49 (15% off)	660 g (30 servings x 22 g)	$2.12 ($1.48 first order, $1.80 recurring)
Momentous Whey Protein Isolate	$69.99 ($52.49 first subscription order at 25% off, then $62.99 at 10% off)	500 g (25 servings x 20 g)	$2.80 ($2.10 first order, $2.52 recurring)

Assumptions: eggs at 50 g each, milk at about 1.03 g per mL, chicken weighed raw. Whole foods bring calories along with the protein (eggs and whole milk carry fat), so if you are cutting hard, the isolate’s near-zero carbs and fat are part of what you pay for.

Read the table this way:

• Real food costs well under the cheapest isolate per gram of protein: $0.60 to $0.82 per 20 g against $1.39 to $2.80, even counting subscription discounts. Nothing in the trial literature says powder builds more muscle than the same grams from food.
• Powder earns its price on convenience. A scoop after training, a shake on a travel day, or a bedtime casein serving is easier than cooking a fourth meal. The ISSN calls supplementation “a practical way of ensuring intake of adequate protein quality and quantity, while minimizing caloric intake,” which is exactly the use case.
• Compare powders on cost per gram of protein, not per tub. The three above look similar on the shelf ($65 to $70) but span $1.55 to $2.80 per 20 g at list price, because protein per scoop and servings per tub differ. Subscription discounts narrow the gap but do not change the order: on recurring orders the three cost $1.39, $1.80 and $2.52 per 20 g.

Is a high-protein diet safe for your kidneys?

For healthy adults, the concern is not supported by the trials. Devries and colleagues’ 2018 meta-analysis of 28 randomized trials (1,358 participants) compared higher-protein intakes (1.5 g/kg or more, 20% or more of calories, or 100 g or more per day) against normal or lower intakes and found the change in glomerular filtration rate did not differ. The authors flag an unclear risk of selection bias, and the analysis covers only people without kidney disease. If you have a kidney condition or are unsure, talk to a clinician before running a 2 g/kg diet; this page is not medical advice.

Where to buy / how to save

The three merchants below are the whey isolates priced in the table. All three publish third-party testing and sell direct, and all three offer a subscription discount that is the main lever on price. Cancel-anytime subscriptions are the cheapest way to buy a tub you would reorder anyway. Legion and Momentous front-load the discount (30% and 25% off the first order, then 15% and 10% on later deliveries), while Transparent Labs takes 10% off every order, so compare the recurring price, not the first-box price.

• Transparent Labs is the value pick of the three at list price: 28 g of protein per serving and 30 servings for $64.99, or $58.49 with the 10% subscription discount, which works out to about $1.39 per 20 g. Skip its collagen if what you want is muscle protein.
• Legion Athletics sells a 22 g-per-serving grass-fed isolate in 15, 30 and 60-serving sizes. At the $69.99 one-time price it sits in the middle of the three per gram; the subscription takes 30% off the first order ($48.99 for 30 servings on 09/28/2026) and 15% off later orders ($59.49, about $1.80 per 20 g).
• Momentous is the NSF Certified for Sport option, which matters if you are drug-tested. It costs the most per gram (20 g per serving, 25 servings, $69.99); the subscription takes 25% off the first delivery ($52.49) and 10% off after that ($62.99, about $2.52 per 20 g).

Whatever you buy, the plan is the same: hit 1.6 to 2.2 g/kg from mostly food, spread it over four feedings, use powder for the meals you would otherwise miss, and recheck the price per 20 g every time a tub runs out. This page will be re-verified and the date at the top updated when the prices or the evidence change.