Protein: how much do you actually need?

Protein might be the most talked about nutrient in fitness, and somehow also the most confusing, because for every person swearing you need a shake every two hours there’s another insisting the whole thing is just marketing, and the supplement industry would quite like you to stay unsure. So let’s clear it up with what the research actually says, minus the powder salesmanship.

Protein is your body’s building material, and not only for muscle, because your skin, hair, hormones, enzymes and immune system are all built and repaired from it while your body constantly breaks tissue down and puts it back together. When you train you add to that repair list, and getting enough protein is what lets the rebuild actually happen, and happen a little better than before, which is the whole mechanism behind adaptation. Fall short and you’re asking your body to renovate without materials.

References

Morton RW et al. Br J Sports Med. 2018;52(6):376-384.doi:10.1136/bjsports-2017-097608Meta-analysis: 49 studies, 1,863 participants. The benefit to fat-free mass plateaued around 1.62 g/kg/day.

Trommelen J et al. Cell Rep Med. 2023;4(12):101324.100 g of protein in one sitting produced a greater, more prolonged (>12 h) anabolic response than 25 g.

Commentary. Int J Sport Nutr Exerc Metab. 2024.Argues the practical implications above have been over-read: participants were recreationally active, not resistance-trained, so it may not extend to resistance-trained young women. An open argument, not settled.

Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press; 2005.The source of the 0.8 g/kg RDA for adults. WHO adopted the same figure in 2007.