Optimal: 1.2–1.6 g/kg/day. ≥0.4 g/kg per meal in older adults (≈32 g for 80 kg) to overcome anabolic resistance. Leucine threshold ≈2–3 g per meal.
Distribution across 3–4 servings with ≥30 g each is critical for maintaining muscle mass with age.
View the study (meta-analysis) →Adults with a hip fracture have doubled mortality; 22–58% die within 12 months.
View the study (cohorts) →Pre-sleep: 30–40 g increase overnight protein synthesis and mass gains.
View the study (RCT) →*⏱ 2 min read
Protein is one of the most essential and debated topics in nutrition, going far beyond its reputation as a building block of muscle by playing a crucial role in metabolism, insulin sensitivity, and the prevention of diseases such as type 2 diabetes and sarcopenia; protein intake, combined with resistance training, drives muscle repair and growth, improves athletic performance, improves metabolic health, and promotes longevity by protecting against age-related frailty.
Starting at age 50, the average person loses approximately 1% of their muscle mass and 3% of their muscle strength each year, with an acceleration after age 75; without regular strength training, the rate of strength loss can reach 4% per year; sarcopenia, or age-related loss of muscle mass, contributes to frailty and increases the risk of falls and fractures, with individuals who suffer hip fractures showing a doubled mortality risk, with 22-58% dying within 12 months.
Stable isotope studies suggest that optimal protein intake is 1.2 to 1.6 grams per kilogram of body weight per day, with the current RDA of 0.8 g/kg being widely considered inadequate for optimal health; a meta-analysis led by Dr. Stuart Phillips found that consuming 1.6 g/kg per day while doing resistance training increased muscle mass by 27% and strength by 10%, compared with those who trained without additional protein; for body recomposition or elite athletes, intakes of up to 2.2 g/kg may be beneficial.
Anabolic resistance, the reduced muscle anabolic response to protein intake that occurs with age, is an important factor in muscle loss; older adults need almost twice as much protein per meal to achieve the same muscle-building effect as young adults, which means they should aim for 0.4 g of protein per kilogram of body weight per meal, equivalent to about 32 g for an 80 kg person, to effectively stimulate muscle protein synthesis; exercising before consuming protein reverses anabolic resistance and allows older adults to respond like young people.
Leucine, a branched-chain amino acid, acts as the main driver of muscle protein synthesis by activating the mTOR pathway, and a threshold of 2-3 grams of leucine per meal is needed to effectively stimulate protein synthesis; animal proteins are superior for muscle protein synthesis because they are more protein-dense, more digestible, and contain a complete profile of essential amino acids including leucine, although people following vegetarian or vegan diets can optimize their intake by consuming higher total amounts of protein and diversifying their sources to create complementary amino acid profiles.
Information, not medical advice. Scientific evidence reflects the quality of the studies.