When you are fat, CJ will say different phrases. For example, when you are fighting he will say "I got weight on my side," or "I may be big, but I ain't slow". The downside to being fat is that when your body fat meter gets full, you run the risk of having a heart attack. This only happens in very rare circumstances. You will return to the nearest hospital. Also, if you have no muscle stat, or very little, you may not be able to climb high walls or "super sprint". When fat, CJ will waddle around like a penguin, and if you look closely (this happens with no shirt) the fat on his body will wobble.