Whether to gain or lose weight, eat every few hours. Lighter, more frequent meals are the ticket to staying lean or adding lean muscle. Eat for what you are about to do, not for what you've done. If you can't flex it, don't carry it. Stay lean and in shape all the time, even when your interest is to gain size.
Lean protein is the key to balancing blood chemistry and building lean muscle.
One half gram per pound of body weight is probably minimal for any healthy diet. Up to a gram, or more, per pound of protein is often needed for gaining muscle. The timing of food intake is as important as the quantity and ratio. Eat carbohydrates with breakfast, early in the day and after training. Divide protein throughout all meals.