Why not have areas on the Fleet, and various planets, a gym, or cafeteria? The purpose of these areas, is over extended periods of time, alter your body type. Perhaps visit the gym once a day for 14 days and you can have Body type 3? visit the cafeteria, and eat low fat/high fat foods to get body type 1 or 4?
Nothing drastic or immediate, but over time. Perhaps consecutive days required.