Lifters understand that they need to consume a sufficient amount of protein if they want to build muscle or just preserve their lean body mass from hard training. Our bodies break down protein into amino acids which are the building blocks that make up our organs, bones, and muscles. The presence of amino acids can actually signal a pathway involved in the regulation of muscle protein synthesis. Where debate arises is how much protein do lifters actually need to consume in a day? The RDA and Institute of Medicine currently recommend 0.8g/kg day, for a 190-lb male. This would equal out to 69g of protein per day. But current research suggests that lifters, regardless of if their goals are adding muscle or reducing body fat, likely need significantly more protein than what the RDA recommends.
A study was conducted to assess the dietary protein requirements of healthy young male bodybuilders on non-training days by using indicator amino acid oxidation as the evaluation measurement. The study revealed that the estimated daily requirement was 1.7g/kg per day to maximize whole body muscle protein synthesis with an upper 95% confidence interval of 2.2 g/kg per day. It’s important to note that the protein amount for these lifters was evaluated on non-training days, which could suggest they could potentially need more on strenuous training days.
Another study reviewed scientific literature regarding natural bodybuilders' nutrition plans prior to competition. It was found that most bodybuilders responded best to 2.3-3.1 g/kg of lean body mass per day of protein. This would average out to be 2.7 g/kg of lean body mass a day, for a 190-lb male with 14% body fat as an example. This would mean they have 163.4 lbs of lean body mass and would need on average around 200g of protein per day. This number is significantly higher than what the RDA recommends.
Fortunately, the science appears to show that if you bump up your protein consumption not only will you be able to support muscle protein synthesis you’ll even be able to lose fat in the process. A different bodybuilder study comparing lifters consuming a “low” 2.3g/kg protein diet to a high 3.4g/kg diet revealed both groups gained the same amount of muscle mass but the high protein group actually lost more body fat despite consuming 400 more calories per day.
A study on young men following a calorie deficit diet with two protein groups, a low protein group of 1.2 g/kg per day and a high protein group of 2.4 g/kg per day following training programs that consisted of resistance training and HIIT for six days a week for a four-week period measured lean body mass, body fat levels, and exercise performance. Over the course of the four-week study, the results showed that the higher protein group had a greater increase in lean body mass while losing a greater amount of fat mass. Both groups had improved measurements in exercise performance.
The take-home message from these studies is that for individuals regularly participating in resistance training they could stand to benefit from higher protein intakes than the RDA’s 0.8g/kg per day.
For individuals seeking to maximize body fat losses on hypo-caloric diets: Higher protein intakes help preserve lean body mass, which is a more metabolically active tissue, and provide satiety. Finally, for individuals seeking to increase muscle mass: higher protein intakes help preserve muscle protein synthesis.