Biglad,

Whey is generally 100% protein. This would be ideal for you as it feeds the muscles without the downside of gaining fat like a carb drink would. From my understanding any protein your body doesn't absorb you shit out.

For someone with a high metabolism, which at 22 stone I doubt you have, carbs are converted and burnt off as energy. If they are not burnt off your body stores the energy (fat).