Post-workout snacks are important because after a hard workout, the body needs glycogen and amino acids to refuel and repair muscle. Having a proper snack within about 30 minutes of a workout will actually help the body repair faster and build muscle more efficiently. The best post-workout snack will consist of mostly carbohydrates and some protein (4 or 3 to 1 ratio). Some simple snacks include: 100% juice, chocolate milk, yogurt, fruit, peanut/almond butter with whole grains, and smoothies. Be sure to drink lots of water after your workout as well to replace the fluids lost through sweat. Try to eat whole foods, rather than bars or protein powder. This article has great suggestions for snacks you can bring with you to the gym.