If you are trying to increase muscle mass with weights and other resistance training exercises, then the timing of food intake is critical. The 60-90 minute time period immediately following your weight workout is the best time to feed your muscles and maximize your recovery/muscle gains. If you miss this window of opportunity, you have lost it forever. A bottle of sports drink will not be enough nutrition during this time period. If you don't like to eat food during this 60-90 minute window, a meal replacement drink will work.