When training its best to use the rest time during exercise to replenish your muscles, using a liquid formatted drink to do this is essential to build muscular growth and maintain a good structure. Like building a house you always need materials to help you bricks, cement, wood, etc. To achieve the final goal of building your body you use the same method, you need intake protein, carbs, fat, amino acids, etc.
Eating all the time can be hard, replace some meals with liquid consumption shakes or smoothies is the best way to make sure all the goodness from every hard workout is stored.
For ideas on protein shakes follow power smoothie