Where the numbers come from
A 2018 meta-analysis by Morton and colleagues pooled 49 studies of people doing resistance training. Gains in muscle mass from extra protein levelled off at about 1.6 g/kg/day, and the statistical upper bound sat around 2.2 g/kg/day. That is well above the general recommendation for adults, which is set to prevent deficiency rather than to support training.
The 1.6 figure is an average. Some people benefit from a little more, which is why aiming somewhere between 1.6 and 2.2 g/kg covers almost everyone.
Spreading it over the day
Total daily protein matters most. Beyond that, spreading it over about four meals of roughly 0.4 g/kg each, about 30 grams for a 75 kg person, is a practical way to reach 1.6 g/kg and seems to make good use of it (Schoenfeld and Aragon, 2018).
Timing around the session matters less than once thought. A meal with protein within a few hours before or after training is plenty; there is no narrow window that closes the moment you leave the gym.
Where to get it
- Meat, fish and eggs.
- Dairy: quark, skyr, Greek yoghurt, cottage cheese and milk are some of the easiest sources to add.
- Legumes, tofu, tempeh and seitan, for plant-based eating. Combining sources over the day covers the amino acids you need.
- Protein powder is food, not magic: convenient when meals fall short, unnecessary when they do not.
When to be careful
For healthy people, intakes in this range have not been shown to harm the kidneys. If you have kidney disease, or a doctor has told you to limit protein, follow their advice rather than any general guide, including this one.