There is an ongoing debate surrounding the maximum amount of protein per meal which can be used for building muscle. This led researchers in the United States to conduct an objective review to determine what the upper limit of protein intake per meal is for optimal muscle growth.
Given the multitude of variables involved in this area of research, it has been a challenging pursuit to quantify the maximum amount of protein intake per meal which can be utilised for building muscle. Daily protein distribution is particularly important for those involved in regimented resistance training or strength training which builds strength, anaerobic endurance, and muscle size, such as those used by body builders to build muscle mass.
The proposed intake to achieve the “muscle full” concept of high-quality protein for maximum muscle protein synthesis in young adults is approximately 20–25g per meal. Any amount of protein consumed above this threshold is believed to be oxidised for energy or undergo a chemical reaction to form other compounds in the body. A review by US researchers published recently in the Journal of the International Society of Sports Nutrition analysed current data to determine what the upper limit of protein intake is per meal. Based on their findings they aimed to elucidate guidelines for the ideal amount of protein per meal to optimise building muscle.
Impact of Digestion and Absorption on Building Muscle
A study conducted by Areta and colleagues which supports the upper limit of 20–25g of protein per meal showed that after giving participants different amount of whey protein over a 12-hour recovery period after they performed the same leg-extension exercise, those who consumed four servings of 20 g of protein had the greatest muscle protein synthesis. This suggests that higher dosages such as 40g of protein offer no additional benefit and they reported the higher dose of protein actually resulted in a lower rise in muscle protein synthesis.
They also reported that there are several factors which influence the metabolism of protein including the composition of the meal, the quality of the protein source, the amount ingested, and the type of exercise performed beforehand. These, along with other variables such as age, amount of lean body mass, and level of fitness also have an impact on the optimal amount of protein per meal for building muscle.
The quality and type of protein ingested can alter the rate at which the protein is absorbed by the body and in turn amino acids availability for muscle protein synthesis. For example, whey protein is a fast-acting protein with an absorption rate of approximately 10g per hour.
Furthermore, meal type is a factor when examining optimum protein levels. Acute meals are those consumed directly after resistance training whereas chronic meals which are meals consumed throughout the day. Both meal types have specific challenges when it comes to comparing different protein amounts and hence adding to the challenge of quantifying the amount of protein per meal to be used for building muscle.
How Much Protein is Needed for Building Muscle?
Based on the literature, the researchers concluded that the most comprehensive findings were by Morton and colleagues who found that for optimal protein synthesis to occur protein intake needed to be 0.4 g/kg/meal, where the protein source was fast acting. This means a 65kg person needs to consume 26g of protein per meal to maximise muscle protein synthesis. However, further research noted that this was an estimated average intake, with older individuals reported to have a higher threshold of 0.6 g/kg/meal and younger men requiring 0.25 g/kg/meal. Given the variables involved in attempting to quantify the maximum amount of protein per meal for optimal muscle growth, these results reinforced the need for personalised diets and training programs.
After examining all of the evidence provided by current the studies in this area, the total daily consumption was indicated to be approximately 1.6 g/k, which equates to 104g for a 65kg person. This amount of protein intake is for those with the goal of building muscles through resistance training are not currently dieting. It is noted this should not be taken as a universal limit and that any protein consumed above it will be wasted or used elsewhere in the body.
Further Research Needed to Quantify Specific Limits
In conclusion, the review suggests the solution to the primary goal of building muscle is to consume 0.4 g/kg/meal of protein over at least four meals per day to reach the daily minimum of 1.6 g/kg/day which would address the metabolism challenges associated with both acute and chronic meals. The upper limit per day was cited at 2.2 g/kg/day, which equates to 0.55 g/kg /meal. However, further research is required to quantify this specific upper limit protein intake per meal.
Written by Lacey Hizartzidis, PhD
Reference: Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr. 2018 Feb 27;15:10. doi: 10.1186/s12970-018-0215-1.
