The short answer
For building muscle, the research-supported range is 1.6–2.2g of protein per kg of body weight per day. For most people, aiming for 2.0g/kg is a practical, effective target that sits within the optimal range without requiring obsessive tracking.
For a 75 kg person, that is 150g of protein per day. For an 80 kg person, 160g. These numbers are achievable with a well-structured diet — they do not require protein shakes, though supplements can help hit targets conveniently.
What the research says
A 2018 meta-analysis published in the British Journal of Sports Medicine, which pooled data from 49 studies and over 1,800 participants, found that protein supplementation significantly increased both muscle size and strength when combined with resistance training. The researchers identified a threshold of approximately 1.62g/kg/day — above which additional protein provided no further benefit for muscle growth in most individuals.
For older adults (over 65), the requirements are higher due to anabolic resistance — a reduced ability of aging muscle to respond to protein. The recommended range rises to 1.8–2.4g/kg/day for this group.
Protein targets by goal
| Goal | Protein (g/kg/day) | Notes |
|---|---|---|
| Sedentary adult (maintenance) | 0.8 | Minimum, not optimal for active people |
| General fitness / health | 1.2–1.6 | Most recreational exercisers |
| Building muscle | 1.6–2.2 | Evidence-supported optimal range |
| Fat loss (muscle preservation) | 1.8–2.4 | Higher end to counteract muscle loss |
| Older adults (65+) | 1.8–2.4 | Compensates for anabolic resistance |
| Elite athletes | 2.0–3.0 | Varies by sport and training phase |
Does timing matter?
Protein timing is far less important than total daily intake. The old idea of a "30-minute anabolic window" post-workout has been largely debunked. Muscle protein synthesis remains elevated for several hours after training.
What does matter slightly is distribution across meals. Research suggests that spreading protein across 3–4 meals of 30–40g each optimises muscle protein synthesis better than consuming most of your protein in one or two large meals. This is because the body can only utilise approximately 20–40g of protein for muscle synthesis at any one time (the exact amount varies with body size and training status).
Best protein sources
Not all proteins are equal. Complete proteins contain all nine essential amino acids and are found in animal sources and some plant sources. Leucine — the amino acid that most strongly stimulates muscle protein synthesis — is highest in animal proteins.
🥩 Animal Sources
Chicken breast (31g/100g)
Beef mince, lean (26g/100g)
Salmon (25g/100g)
Eggs (13g/100g)
Greek yoghurt (10g/100g)
Cottage cheese (11g/100g)
🌱 Plant Sources
Tofu, firm (17g/100g)
Edamame (11g/100g)
Lentils, cooked (9g/100g)
Chickpeas (9g/100g)
Tempeh (19g/100g)
Seitan (25g/100g)
Is too much protein harmful?
For healthy adults with normal kidney function, consuming up to 3.0g/kg/day for extended periods has not been shown to cause harm in multiple safety studies. Concerns about kidney damage from high protein intake apply to people with pre-existing kidney disease — not to healthy individuals.
The main practical downside of very high protein intake is that it displaces other macronutrients and can reduce carbohydrate intake enough to impair training performance. Eating 2.2g/kg/day is the practical ceiling for most people — going higher is unnecessary and doesn't improve muscle growth.
Key takeaways
- Aim for 1.6–2.2g of protein per kg of body weight daily for muscle building.
- Distribute across 3–4 meals with 25–40g protein each.
- Prioritise complete proteins, especially around training.
- Total daily intake matters more than timing.
- Protein requirements are higher during fat loss and for people over 65.