Benefits of increased protein intake
Some may now argue that there are studies with bodybuilders showing that protein consumption of 1.2g-1.5g / kg body weight is sufficient to maintain nitrogen balance. Because of the protein intake being too low, the body’s own protein breakdown would be high in return. This would mean an increased degradation of muscle cells, which in turn would result in an increased nitrogen loss, which would be detectable. However, this nitrogen balance merely states that the body is able to maintain its muscle mass. However, most bodybuilders are interested in gaining muscle not just maintaining. For this, however, more protein must be absorbed through the diet than is needed to maintain muscle mass. Studies have also shown that increased protein intake leads to increased nitrogen excretion. This means that there can be too high of an intake, and too low of an intake.
Also, the argument that a constantly increased protein intake causes a larger portion of amino acids to be burned off is not exactly right. Although it is true that excess amino acids are used for energy, the biochemical conversion into energy or into storage-forms requires a more energy and detours than for example fat . This is certainly a better option, than when comparing the storage as body fat, as it happens with an excess of fat.
However, the human body does not just break down a certain amount of the body’s own proteins, which are then replaced by food. Rather, a part of the degraded protein is used to build body protein again. Overall, the human body degrades about 3-5g of protein per kg of body weight per day. However, most of this is broken down protein is re-supplied to the synthesis, so effectively only a loss of about 50g occurs. This corresponds to the recommended protein amount (DRI), which thus represents the minimum maintenance requirement without physical activity. Imagine it like building a wall of legos, then breaking the wall down, and rebuilding it with the same components. But along the way you lose some legos because they were broken or faulty, which is why you need new legos.
Furthermore, there is also the protein degradation that occurs when the concentration and overall balance of amino acids in the human body falls below a certain level. This is can occur during hard training, hard work or stressful situations, where amino acids are also used to generate energy. This means that the extra amino acid requirement causes the body to break down muscle tissue first in order to meet this demand. However, this temporary damage to the tissue in turn leads to increased protein synthesis after training (if enough protein is provided via food). For this reason, a protein shake near the end of the training may be beneficial to support these (re-)building processes.
Last but not least, there are studies that show that increased protein intake also increases the body’s IGF-1 levels (insulin-like growth factor). IGF-1 is a key hormone when it comes to anabolic (:to build up) processes in the human body. It also inhibits catabolic (: to break down) processes.