How much protein you actually need

The number, and where it comes from

Protein is the one macronutrient where the recommendation for lifters differs substantially from the general population guideline, and it is worth knowing why rather than just accepting a number from a supplement label.

The reference point is a systematic review and meta-analysis of 49 studies with 1,863 participants, which found that protein supplementation increased strength and muscle size, and that the benefit plateaued at around 1.6 g per kg of body weight per day. The upper bound of the confidence interval reached 2.2 g/kg, which is where the commonly quoted range comes from.

Two things to notice. First, the government-issued 0.8 g/kg figure is a minimum to prevent deficiency in sedentary people — it was never intended as an optimum for someone training. Using it as a target while lifting is a genuine mistake, not a conservative choice.

Second, the range above the plateau is not magic. Going from 1.2 to 1.6 g/kg matters. Going from 2.2 to 3.0 g/kg does close to nothing for muscle, though it is harmless and can help with satiety.

Why body weight, and when to use lean mass instead

Most recommendations scale to total body weight, which is simple and works for most people. It gets distorted at the extremes.

• If you carry a lot of fat, scaling to total weight overestimates your needs, because fat tissue is not metabolically demanding in the same way. Scaling to a target weight, or to lean mass, is more accurate.
• If you are very lean, particularly in a deficit, scaling to lean mass is the better approach — and the literature on fat-loss phases uses exactly that, recommending 2.3–3.1 g per kg of fat-free mass.
• For everyone in the middle, total body weight at 1.6–2.2 g/kg is close enough that the difference does not matter.

Do not spend long on this. The difference between a well-chosen target and a slightly wrong one is much smaller than the difference between hitting a target and not tracking at all.

The 30 g per meal myth

You have probably been told the body can only use 20 to 30 g of protein at a time and the rest is wasted. This is one of the more confidently repeated claims in nutrition, and the evidence has moved decisively against it.

The claim came from studies that measured muscle protein synthesis for only three to five hours after a meal. Within that window, larger doses did not look better. A 2023 study extended the measurement to twelve hours and compared 25 g against 100 g of protein after resistance exercise. The 100 g dose produced a greater and substantially more prolonged anabolic response — around 20% higher in the first four hours and around 40% higher from hours four to twelve — with no ceiling detected. The 25 g dose was fully absorbed within about six hours; the 100 g dose was still being digested at twelve.

That said, spreading protein across three to four meals is still a reasonable default — see protein distribution across the day. It is a mild optimisation and an easy habit, not a requirement.

Protein quality and sources

Quality means two things: the amount of leucine (the amino acid that most strongly triggers the anabolic response) and how complete the amino acid profile is.

• Animal sources are more efficient per gram. Meat, fish, eggs, dairy and whey are complete and leucine-rich.
• Plant sources work but need more attention. Lower leucine, often limited in one amino acid. Higher total intake and variety solves it — see vegetarian and vegan protein strategies.
• Whey is convenient, not magic. It is fast-digesting, cheap per gram of protein and easy to hit a target with. Food does the same job.
• Total daily intake matters far more than source distribution once you are hitting a sensible target with a varied diet.

Useful reference points per portion: 100 g cooked chicken breast ≈ 30 g; 100 g cooked mince ≈ 26 g; two eggs ≈ 12 g; 170 g Greek yoghurt ≈ 17 g; 100 g tofu ≈ 12 g; 100 g cooked lentils ≈ 9 g; a scoop of whey ≈ 24 g.

Is high protein safe?

Worth addressing directly, because the concern is common and largely unfounded for healthy people.

• Kidneys. High protein intakes do not damage healthy kidneys. This has been examined repeatedly, including in trained populations eating well above 3 g/kg for months. If you have existing kidney disease, that is a genuine medical exception — follow your doctor's guidance.
• Bones. The old "protein leaches calcium" claim has been reversed; higher protein intake is associated with better bone density, particularly alongside resistance training.
• Practical limits. The real constraint is appetite and displacement. Very high protein crowds out carbohydrate and fat, which can hurt training performance and hormones — see dietary fat and hormones.

Common questions

What if I train fasted or eat one meal a day?

Total daily intake still dominates, and the twelve-hour data suggests large single doses are handled better than previously thought. It is not the optimal structure, but it works.

Do I need protein immediately after training?

No. The "anabolic window" is hours wide, not thirty minutes. See meal timing.

Is more than 2.2 g/kg ever worth it?

In a deficit, yes. Otherwise it mostly helps with fullness rather than muscle.

Can I get enough without supplements?

Easily, if you eat animal products. Plant-based diets at high targets often benefit from a powder for convenience rather than necessity.

Does protein help with fat loss?

Indirectly and substantially: it is the most satiating macronutrient, has the highest thermic effect, and protects muscle in a deficit — see recovery in a calorie deficit.

Should older adults eat more?

Toward the upper end of the range. The anabolic response to a given dose of protein is blunted with age, so both total intake and per-meal doses should be generous.

How do I actually hit the number?

Anchor a protein source to every meal and count for a week. Most people who think they eat enough protein are 40 to 60 g short, and one week of honest tracking reveals it.

The practical version

• 1.6–2.2 g per kg of body weight per day covers everyone training to build muscle.
• Gains plateau at about 1.6 g/kg in the meta-analysis; the upper bound is 2.2.
• In a deficit, go higher: 2.0–2.6 g/kg, or 2.3–3.1 g/kg of fat-free mass.
• The 30 g per meal ceiling is not real. Twelve-hour data found no upper limit.
• Animal sources are more efficient; plant-based diets need 10–20% more and variety.
• High protein does not harm healthy kidneys or bones.