Determining optimal protein intake for muscle growth using evidence based studies.

Protein consumption is essential for maintaining good health and promoting muscle growth and recovery. Sorting through various studies and dispelling long-standing myths can complicate the task of determining the appropriate daily protein intake. Let's embark on a journey together to examine several studies on protein consumption and their results, in order to understand the ideal protein intake for different people.

These studies were selected due to their utilisation of a consistent control for energy intake, either through individual needs or by ensuring equal energy intake across all experimental settings, allowing for variations in the proportion of protein in the diet between groups. Studies employing less reliable methods like nitrogen balance or markers of lean body mass changes were included solely because they incorporated controls for dietary adaptation periods.

Summary of the evidence.

Tarnopolsky et al. (1992):

• Observed no differences in whole-body protein synthesis or lean body mass in strength athletes consuming either 1.4 g/kg or 2.4 g/kg over two weeks.

• High protein intake led to increased protein oxidation, indicating a nutrient overload.

Walberg et al. (1988):

• Found that 1.6 g/kg was sufficient to maintain positive nitrogen balance in weightlifters undergoing weight cutting over a seven-day period.

Tarnopolsky et al. (1988):

• Elite bodybuilders (with over five years of experience, potential previous use of androgens) maintained positive nitrogen balance with only 0.8 g/kg over ten days.

• 1.0 g/kg was sufficient to maintain lean body mass in bodybuilders over two weeks.

• The authors suggested that 1.2 g/kg may be sufficient for bodybuilders.

Lemon et al. (1992):

• Found no differences in muscle mass or strength gains in novice bodybuilders consuming either 1.34 g/kg or 2.62 g/kg over a four-week period.

• Based on nitrogen balance data, the authors recommended 1.5 g/kg.

Hoffman et al. (2006):

• Found no differences in body composition, strength, or resting hormonal concentrations in strength athletes consuming either 1.6 g/kg or >2.0 g/kg over three months.

Bayesian Research team, Cambridge University:

•  Found no evidence supporting higher protein intakes for recovery after intense workouts.

Additional Studies:

• Over 20 other studies, consistently failed to find any benefits of protein intake exceeding 1.6 g/kg/d.
  

So what does the research tell us?

According to the findings of these peer-reviewed studies, the ideal protein intake is 1.6g/kg/day. The research indicates that exceeding this amount does not offer additional benefits for muscle growth based on the data from all studies (1). While individual factors like athletic background, objectives, and general well-being should be taken into account, consuming less than 0.9g/kg/day of protein does not support positive nitrogen balance, muscle maintenance, and strength development across all demographics (2). The studies collectively demonstrate that the timing of protein intake has minimal impact on muscle protein synthesis efficiency, yet consuming more than 25g of protein every 3 hours per meal does not provide any added advantage (3).

So, how much protein should I eat to optimise muscle growth?

To optimise muscle protein synthesis, strength gains, and recovery, it is advised to consume a minimum of 0.9 g/kg/day and a maximum of 1.6 g/kg/day.

For best protein absorption, it is advised to split your daily protein intake into intervals of 3 hours, with each interval having 25g of protein. Additional meals can be added if necessary to reach the daily protein target.

The Equation!

1.6 x Body weight in KG ÷ 25 (g of protein in each sitting) = number of meals per day.

For instance, if you weigh 82kg and want to maximize muscle protein synthesis, you should consume 131g of protein daily in 25g portions every 3 hours. The most effective approach would be to have 25g of protein in each of your 5 meals scheduled at 7am, 10am, 1pm, 4pm, and 7pm.

References:

(1) The effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults https://pubmed.ncbi.nlm.nih.gov/28698222/

(2) Nutritional interventions to augment resistance training-induced skeletal muscle hypertrophy https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4558471/

(3) Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis https://pubmed.ncbi.nlm.nih.gov/23459753/