Nutrition is such a subjective term and we all interpret what good nutrition is differently.  What we eat greatly impacts how we feel, what we're able to do, and sometimes we can get it wrong when we're looking to  support our activities with the types of food we eat.  When I help someone dial-in their sports nutrition while they're training, I also look at supporting good overall health too.  Why would you want your health to suffer if you're training to be at the top of your game on race day!