Brain

I don't believe there is a relation between fat or thin for use of brain. Humans only use about 10% of their brain at this time. If we could get more intelligent by being thin I bet people would be running to their doctors for diet pills.

Really dont know this relation but its a fact that the size of your head will determine the brain that you will have. But it does not matter how much brain you have what matter is that how much of the brain you use and that makes genius or not Einstein used more brain then any other person on this planet...!