This is the case of too much of a good thing. Protein is an important nutrient and your body needs around 1g/ kg of body weight per day. (e.g. 70 kg person would need approx 70g protein each day). However, high protein diets are quite popular at the moment and people are often have much more protein than they need. Excess protein intake cause calcium excretion and lead to weaker bones. The key message here is balance!