Most of the studies are indicating that a maximum intake of 1,5 grams of protein per 1 kg of body mass (or 0.7 grams of protein per 1 lbs of body weight) is enough to stimulate protein synthesis on athletes that are training hard. But most of the athletes (including bodybuilders) are consuming much bigger quantities than this. There are many scientific proofs that an excessive protein intake leads to an increase in size of the liver and kidneys and also increases the blood acidity.
In a lab experiment, Spanish scientists have shown that weight training reduces the side effects of protein-rich diets. The reduction of these negative effects was seen in the fat levels in blood and liver, in blood urea and also in the size of the kidneys and the liver. From this study we can conclude that weight training is very important for the health of those people that are on a high protein diet. (Nutricion Hospitalaria, 26:1478-1486, 2011)
Article by Craig Wilson