You can use the following cheats:
If you want CJ to get fat, but not at max, do not use the "max fat" cheat. Insted, go to a fast food restaurant and feed him, but do not buy more than 10 meals consecutively, otherwise Carl will vomit. When he vomits, he loses fat and health.
This post has been edited by typicalgamer on Saturday, Jul 28 2012, 19:12