About a year or so ago, there was a posting on here by a member (can't remember his name) but he was taking in 5-6 protein shakes per day in addition to 2 meals consisting of fish (canned tuna I think) and rice. He did this for about three months, made great gains in addition to lower bodyfat levels, but when he went to the doctor for bloodwork before starting his cycle, the blood work showed some major trouble going on with this type of diet. I can not remember what exactly was found, but he was very very borderline of developing severe health problems. Maybe some mod or vet will remember more of this and find the post. It was a very detailed and interesting read.
Make sure you are taking a good multivit daily to help round off what you may be missing.