When it comes to working out, you always want to make sure you have ample energy. However eating too close to vigorous exercise is a recipe for discomfort, but heading to the gym hungry isn't ideal either — something I learned during a recent session with my Crunch trainer, Tim Rich. Not being adequately fueled led to a weak-feeling workout and unusually sore muscles the next day. Wanting to maximize the potential of my training sessions, I turned to nutritionist Heidi Skolnik, MS, CDN, FACSM, and author of Nutrient Timing for Peak Performance to find out what to eat, and when, before heading to the gym. Keep reading to see the simple guidelines that Heidi suggests.