I don't like to eat alot before i take off, so i eat things that only require a small serving, but have alot of carbs. I usually eat a yogurt with raisins and a bannana, thats about 90g of carbs and thats some good fuel right there. For your legs i reckon you just keep yourself hydrated. The way you know whether you gave your muscles enough water or not is if you get cramps, muscle cramps are usually a sighn of poor hydration.