Best Protein Intake for Muscle Growth: The Research

How Much Protein Do You Need to Build Muscle?

Protein is the essential building block of muscle tissue. Every gram of skeletal muscle in your body is made of protein chains that your body broke down from dietary protein, absorbed as amino acids, and reassembled into new muscle fibres. Without adequate dietary protein, muscle protein synthesis — the process of building new muscle — cannot occur at the rate required for meaningful muscle growth.

The official RDA of 0.8g of protein per kilogram of body weight was designed to prevent deficiency in sedentary adults — not to optimise muscle growth in active individuals. The research is clear: for anyone training with weights, the RDA is substantially too low.

The Research-Based Recommendations

A comprehensive 2018 meta-analysis published in the British Journal of Sports Medicine, covering 49 studies and 1,863 participants, found that protein supplementation significantly increased muscle mass gains from resistance training. Critically, it found that muscle protein synthesis was maximised at approximately 1.62g of protein per kilogram of body weight per day — with no additional benefit observed beyond this threshold during a caloric surplus.

However, more recent research and practical experience with elite athletes suggests that higher intakes of 1.8–2.4g/kg/day may be beneficial during aggressive fat loss phases, where the risk of muscle breakdown is higher and the protective effect of dietary protein is more pronounced.

Timing: Does When You Eat Protein Matter?

The anabolic window — the idea that you must consume protein immediately post-workout to maximise muscle growth — is far less important than previously believed. A 2013 meta-analysis in the Journal of the International Society of Sports Nutrition found no significant difference in outcomes between consuming protein immediately post-workout versus at other times, as long as total daily protein intake was adequate.

More practically important is protein distribution across the day. Research by Norton and Layman suggests that muscle protein synthesis is maximised per meal at approximately 0.4g of protein per kg of body weight. Consuming protein in 3–5 meals throughout the day — rather than one or two large portions — produces greater cumulative MPS stimulation over 24 hours.

The Best Protein Sources

Animal sources (complete amino acid profiles, high leucine): chicken breast (31g per 100g), canned tuna (26g), lean beef (26g), Greek yoghurt (10g), eggs (13g per 100g), cottage cheese (11g), whey protein (24–27g per scoop).

Plant sources: tofu (17g per 100g), tempeh (19g), edamame (11g), lentils (9g cooked), black beans (8g cooked), quinoa (4g). Plant proteins are often lower in leucine and have lower digestibility — aim for the higher end of protein targets and combine sources to ensure complete amino acid profiles.