The recommended protein intake for muscle gain has been a subject of debate in the scientific community, and there is no consensus on the exact amount of protein required for optimal muscle growth. However, a common recommendation is to consume approximately 1.6-2.2 grams of protein per kilogram of body weight per day for those engaging in resistance training to promote muscle protein synthesis and muscle growth.
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One of the earliest studies to suggest the 1 gram of protein per kilogram of body weight recommendation was conducted by Lemon et al. (1992), which showed that a protein intake of 1.6 grams per kilogram of body weight per day was associated with a positive protein balance and increased muscle protein synthesis in healthy adults engaged in resistance exercise. However, this study had a small sample size, and subsequent research has challenged the notion that 1 gram of protein per kilogram of body weight is the optimal amount for muscle gain.
A review article by Phillips and Van Loon (2011) analyzed the available literature on protein intake and muscle protein synthesis and concluded that a protein intake of approximately 1.6 grams per kilogram of body weight per day is likely optimal for most individuals engaging in resistance training. Similarly, a review article by Morton et al. (2018) suggested that a protein intake of 1.6-2.2 grams per kilogram of body weight per day is necessary for maximizing muscle protein synthesis and muscle growth.
It's worth noting that these recommendations are not absolute, and the optimal protein intake may vary based on factors such as age, sex, and training status. Additionally, some studies have suggested that higher protein intakes may not necessarily result in greater muscle gains, as the body can only use so much protein for muscle synthesis at any given time. Therefore, consuming protein in excess of one's needs may not provide additional benefits for muscle growth and could be unnecessary and potentially harmful in some cases.
Lifestyle habits can significantly impact its efficiency. Adequate protein intake is essential for muscle growth, but other factors such as exercise, sleep, stress, and alcohol consumption can interfere with protein synthesis and muscle hypertrophy.
Exercise is a critical stimulus for muscle growth, but excessive exercise without sufficient recovery can hinder protein synthesis. Prolonged endurance exercise and high-intensity training can increase cortisol levels, which can lead to muscle protein breakdown and impaired muscle growth. Conversely, resistance training can stimulate protein synthesis, but without adequate rest and recovery, protein turnover can be negatively affected. A study by Phillips et al. (2016) found that consuming protein before sleep can improve muscle protein synthesis rates and promote muscle hypertrophy in response to resistance exercise.
Sleep is crucial for muscle recovery and growth, and inadequate sleep can disrupt protein synthesis. Sleep deprivation can reduce growth hormone and testosterone levels, which are essential for muscle growth, and increase cortisol levels, leading to muscle breakdown. In a study by Dattilo et al. (2011), sleep deprivation was found to impair muscle recovery and lead to a reduction in muscle protein synthesis rates.
Stress is another factor that can negatively impact protein synthesis. Chronic stress can increase cortisol levels, leading to muscle protein breakdown and impaired muscle growth. In a study by Stavrou et al. (2019), stress was found to be associated with reduced muscle mass and strength in older adults.
Alcohol consumption can also interfere with protein synthesis and muscle growth. Excessive alcohol consumption can reduce testosterone levels and increase cortisol levels, leading to muscle breakdown and impaired muscle growth. In a study by Parr et al. (2014), alcohol consumption was found to reduce muscle protein synthesis rates and impair muscle recovery.
In summary, while the evidence suggests that a protein intake of around 1.6-2.2 grams per kilogram of body weight per day may be optimal for muscle growth in individuals engaged in resistance training, it's important to note that these recommendations are not absolute, and may vary based on individual factors. Other lifestyle factors such as exercise, sleep, stress, and alcohol consumption can interfere with protein synthesis and muscle hypertrophy. It's important to consider these factors when trying to optimize muscle growth and overall health.
References
Dattilo, M., Antunes, H. K., Medeiros, A., Mônico Neto, M., Souza, H. S., Tufik, S., & de Mello, M. T. (2011). Sleep and muscle recovery: endocrinological and molecular basis for a new and promising hypothesis. Medical hypotheses, 77(2), 220-222.
Lemon, P. W., Tarnopolsky, M. A., MacDougall, J. D., & Atkinson, S. A. (1992). Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. Journal of Applied Physiology, 73(2), 767-775.
Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., ... & Phillips, S. M. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 52(6), 376-384.
Parr, E. B., Camera, D. M., Areta, J. L., Burke, L. M., Phillips, S. M., & Hawley, J. A. (2014). Alcohol ingestion impairs maximal post-exercise rates of myofibrillar protein synthesis following a single bout of concurrent training. PloS one, 9(2), e88384.
Phillips, S. M., & Van Loon, L. J. (2011). Dietary protein for athletes: from requirements to optimum adaptation. Journal of sports sciences, 29(sup1), S29-S38.
Phillips, S. M., Chevalier, S., & Leidy, H. J. (2016). Protein “requirements” beyond the RDA: implications for optimizing health. Applied Physiology, Nutrition, and Metabolism, 41(5), 565-572.
Stavrou, S., Nicolaides, N. C., Papageorgiou, I., Hadjigeorgiou, G. M., & Koutsilieris, M. (2019). Stress, aging, and frailty: A Mediterranean approach for healthy aging. The Journal of frailty & aging, 8(1), 40-47.