The intake of protein at the level of 0.8-2.0 g protein / kg BC / day is considered the norm necessary to maintain the nitrogen balance of the adult body, whereas people leading active life mode need more protein than those who do not practice sports. The right amount of protein in the diet guarantees better adaptation of the body to physical exercise, it is necessary for the regeneration of muscle fibers and the increase of lean body mass.
The recommended level of protein in the diet of people practicing sports is 1.2-2.0 g / kg body weight / day, with lower values for trained people and endurance sports (including long-distance running, cycling, swimming). Higher values are recommended for non-trained people, in the period of intense training, or during strength sports and in the period of building muscle mass.
When it is too much of protein ? Compliance with the recommended norms is important because excessive protein intake (over 3g / kg body weight) instead of being beneficial can be detrimental to health. Unused surplus proteins burden the liver and kidneys, hence the long-term use of high-protein diet may end up in the failure of these organs. In addition, excess protein acidifies the body, increases the excretion of calcium in the urine and promotes the accumulation of intestinal gases (especially in the case of high consumption of products such as eggs, some types of cheese, meat and fish).
So that the muscles grow ... Protein can be used to build muscle only when we provide the body with an adequate amount of energy from non-protein sources. With insufficient energy from carbohydrates and fats, proteins are used as a source of energy. This means a decrease of the available amono acids quota for the synthesis of own proteins. Too low calorie diet is one of the reasons for the lack of muscle mass growth despite high protein intake.