If anyone is in the mood to spend a lot more time preparing food and more time eating, the raw paleo vegan diet is for you. For those that don't have as much time, eating more vegetables, including some raw ones, is probably nearly as good.
The only reason I point out that raw paleo vegan is a possible diet is to expand your thinking. We, in the United States, often have an unhealthy relationship with food. We think of it emotionally, not logically. As a master of science, while I still have emotions about the food I eat (chocolate! coffee! cheese!) the logical part of my brain continually asks the question, 'what is possible?' In this particular context the question is, 'what food, or diet structure, makes it most possible for me to achieve my athletic goals?' Truth be told about all I really know is eating four or more servings of vegetables a day is a great way to strengthen your immune system and digestive system, runners need carbohydrates for races two hours and under, and getting a fair amount of protein (1g/kg per day) helps your body recover.
I'm not recommending anyone become a raw paleo vegan, but it can be done, and chances are cutting out the refined sugar and fat from a standard western omnivore diet will probably make you a little more lean.