It also depends how much of the weight gain was 'water weight'. And how quickly you gained the weight - If you slowly gained it you have a better chance of keeping it - basically if your body has become accustumed to it's new size. To add to this PCT is important - doing it right can make a big difference, This also includes what you do in the gym during post cycle therapy and what your diet is like.
As far as gym workouts while recovering you'll have a much lower supply of androgens in your system, so workouts should be kept to minimal amount. The logic behind this is that if you continue to breakdown muscle, yet do not have the androgens available to stimulate repair, you will end up losing this muscle developement.
decrease the volume lifted in the workouts, the length of the workouts and the frequency of the workouts. However do not decrease the intensity as you still want to maintain those muscular nervous conections and the muscle itself.
Be prepared to see yourself soften up for a while - if you do your pct correctly, it will only be temporary! Once you are fully recovered it is amazing what size you will be able to hold naturally compared to your natural pre steroid 'peak'
As far as diet goes, I don't feel eating a lot is going to do anything for you except make you fat. Keep your protein intake steady, but by no means force feed yourself, since for the first little while during pct you won't have the androgens available to do anything with that protein anyway.