I train for about 25 to 30 hours a week so I need to eat a lot. You just need to have a generally healthy diet. You need to be eating foods with lots of vitamins and minerals. You need to make sure you eat properly in order to give yourself the best chance of performing and recovering from training and competing.
Triathlon has quite a short season. It only runs from May to September so there's a lot of time when you're not racing. So I try to set myself the target of doing a certain amount of training every week and things like that.