The standard protein recommendation — 0.8g per kilogram of bodyweight per day — was set to prevent deficiency in sedentary adults. It was never intended as a target for people trying to maintain or build muscle mass. For active adults over 40, it is almost certainly insufficient.
Anabolic resistance
With age, skeletal muscle becomes less responsive to the anabolic stimulus of protein intake. This phenomenon, known as anabolic resistance, means that older muscle requires both a larger protein dose per meal and a higher total daily intake to achieve the same level of muscle protein synthesis as younger muscle.
Current evidence suggests that adults over 40 who train regularly require between 1.6 and 2.2g of protein per kilogram of bodyweight per day to optimise muscle protein synthesis and preserve lean mass. For a 80kg individual, that's 128–176g per day — significantly above the standard recommendation.
Distribution matters as much as total intake
Protein distribution across meals is as important as total daily intake. Research consistently shows that muscle protein synthesis is maximised when protein is distributed across 3–4 meals of 30–50g each, rather than concentrated in one or two meals. The leucine threshold — the minimum dose required to trigger maximal muscle protein synthesis — also increases with age.