Fats and carbohydrates, eat your hearts out—protein is the macronutrient of the moment. Rich people love the stuff. They treat it like ambrosia. Are they onto something?
Having protein on your plate is important. It is made up of amino acids, of which the body needs 20 types in order to grow, produce hormones and stay healthy. Nine of these amino acids must come from food. The World Health Organisation recommends 0.83 grams of protein a day per kilogram of body weight (g/kg) for healthy adults to maintain muscle and tissue health.
Elderly folk may be better off eating more, since muscles wither with age and older bodies are less efficient at absorbing protein. A review published in Nutrients in 2021 suggested that a ratio closer to 1.2g/kg, together with resistance training, could help limit muscle shrinkage in older people. Children and teenagers, who are still growing, may also want more than the minimum, depending on how active they are. A paper from 2020 suggested that pregnant and breastfeeding women need double the recommended amount to maintain muscle mass and feed their child.
To build muscle mass, the International Society of Sports Nutrition has recommended a daily protein intake of between 1.4g/kg and 2g/kg, combined with resistance training. A meta-analysis published in Sports Medicine in 2022, though, found that eating more than 1.6g/kg does not lead to further muscle growth.