1.2–2.2 g/kg/day depending on goal; distribute across 3–4 servings of ≥30 g (≥40 g at age >65 to overcome anabolic resistance).
Increasing intake from 1.2 to 1.6 g/kg/day with resistance training: +27% lean mass and +10% strength versus lower intakes.
View the study (meta-analysis) →Associations with mortality appear only with unfavorable lifestyle factors; exercise neutralizes the theoretical IGF-1-mediated risk.
View the study (cohorts) →People without prior kidney disease: does not harm kidney function even at 3.2–4.5 g/kg/day for up to a year.
View the study (meta-analysis) →*⏱ 3 min read
Protein remains, in some ways, a controversial topic: some argue that it should be restricted in favor of longevity and cancer risk reduction, while others advocate maximizing intake to build muscle mass and improve performance, but the most honest answer is that the current official recommendation does not adequately reflect the available scientific evidence and that the optimal range is systematically underestimated.
The current recommended daily allowance of 0.8 g/kg/day describes the minimum to avoid deficiency, not the optimal intake for performance or aging; it was built on nitrogen balance studies with known methodological flaws, such as incomplete urine collection and the inability to capture nitrogen losses through sweat, feces, skin, and breath, which systematically underestimates the true protein needs of adults.
Stable isotope techniques, more accurate than nitrogen balance studies, consistently point to 1.2-1.6 g/kg/day as a realistic threshold for maintaining protein balance and supporting muscle-centered outcomes such as strength and lean body mass, which represents 50-100% more than current recommendations; and for older adults the situation is even more pressing because of anabolic resistance.
Anabolic resistance is the reduced sensitivity of aging muscle to the same amino acid signal that drives muscle protein synthesis in young people; young people saturate muscle protein synthesis with \~0.24 g/kg per meal (about 20 grams for an 80 kg person), but older adults need \~0.4 g/kg (about 32 grams) to reach the same ceiling, which means that distributing protein across 3-4 meals with a minimum of 30-40 grams each is critical for maintaining muscle mass with age.
A widely cited meta-analysis in resistance-trained adults found that increasing intake from 1.2 to 1.6 g/kg/day improved outcomes: lean mass increased 27% more and strength 10% compared with lower intakes; there is a threshold of diminishing returns around 1.6 g/kg/day for most people, although a practical target of 2 g/kg/day helps ensure that on days when you eat less you still reach the minimum of 1.6 g/kg, because the cost of falling short on protein is greater than the marginal cost of overshooting.
In people without preexisting kidney disease, high-protein diets do not harm the kidneys: the increase in filtration and nitrogen markers reflects a normal adaptation to processing more protein, not dysfunction; even extreme intakes of 3.2-4.5 g/kg/day for up to a year in athlete populations show no adverse changes in standard kidney or liver markers, and emerging studies suggest that higher intake is associated with lower mortality even in people with chronic kidney disease.
The narrative that high protein means more IGF-1/mTOR and therefore faster aging and cancer comes from protein restriction studies in laboratory animals and from observational links in humans that do not adequately control for confounding factors; among healthy, active people, these associations are attenuated or disappear, because exercise redistributes IGF-1 toward muscle and brain, lowers its circulating levels, and increases its binding to protective proteins, fundamentally changing the biological equation.
Information, not medical advice. Scientific evidence reflects the quality of the studies.