What will happen if I eat too much protein?
In extreme situations, you might develop kidney stones, liver problems and gout. But unless you are relatively inactive and are suffering from preexisting conditions like kidney disease or cirrhosis of the liver or are eating ridiculously high levels of protein (600g+ daily) for extended periods of time, the odds of serious deleterious effects are rather remote.
Vegetarians, macrobioticists, readers and proponents of The China Study will have you believe that high protein diets are unhealthy and lead to certain chronic conditions. However, association cannot predict correlation or causation, a comment that we have all heard before.
Other confounding factors such as contamination due to antibiotics, hormones, pesticides, additional processing chemicals and cholesterol associated with animal protein sources are much more likely areas of concern than the high intake of protein itself.