Muscle protein synthesis, the process by which the body builds and repairs skeletal muscle, becomes less efficient with age. Research has established that older muscle is less sensitive to the anabolic stimulus of dietary amino acids, a phenomenon called anabolic resistance. The practical consequence is that adults over 35 require a higher protein intake, both total daily and per meal, to achieve the same rate of muscle protein synthesis that a 25-year-old achieves on lower doses.
The Evidence on Optimal Intake
The current recommended daily allowance for protein is 0.8 grams per kilogram of body weight. This figure was established to prevent deficiency in the general population, not to optimise muscle maintenance in ageing adults. The research evidence now consistently suggests that adults over 35 should target 1.6 to 2.2 grams of protein per kilogram of body weight daily to meaningfully counteract anabolic resistance and support muscle preservation.
Per-Meal Distribution Matters
Research from the University of Texas Medical Branch found that muscle protein synthesis is maximally stimulated by 30 to 40 grams of high-quality protein per meal. Eating 20 grams three times a day produces inferior outcomes to eating 35 grams twice a day, even at the same total daily intake. Spreading protein evenly across three meals, each containing 30 to 40 grams, appears to be the optimal distribution for adults over 35.
Best Whole Food Protein Sources
- Eggs: complete amino acid profile, highly bioavailable, approximately 6 grams per egg
- Lean beef and lamb: high in leucine, the amino acid most responsible for triggering muscle protein synthesis
- Greek yoghurt and cottage cheese: casein protein that is slowly digested, supporting overnight muscle protein synthesis
- Salmon and mackerel: protein combined with anti-inflammatory omega-3 fatty acids
- Chicken breast: lean, high-protein, approximately 31 grams per 100 grams cooked
- Lentils and chickpeas: lower leucine content than animal protein but meaningful contribution within a varied diet