Your diet should be high in protein, high in complex carbohydrates and low-moderate in fat, but still with enough essential fatty acids. Particularly omega 3 fatty acids. Also don't forget vegetables.
You should have a good idea on dieting if your lifting you shouldn't be improving your diet when hoping on gear you should have a consistent diet year round depending on your goals
And when you come of you should have more focus on your diet trying to hold onto what you gained