Ugh. I'll go out on a limb here and say that diet isn't as important as people think unless you're trying to make bodyweight changes. Some people eat 10k calories from McDonalds per day and are strong as hell. I don't see how doing something like eating 3k of calories from McDonalds is so awful for performance. Seriously. I know people who eat desserts as their dinner and perform fine. Just eat enough food to have energy to train and don't get fat. That is my nutrition advice. Wanna know what my girl long jumper's pre-meet meal was before her PR? Swedish fish.
try telling that to olympic athletes/ coaches. im prety sure they would laugh at that. nutrition is what separates the elite from the "pretty good" along with a lot of other factors including discipline, which ties into diet. it takes discipline to resist the temptation of always eating fast food. elite athletes have that discipline. its the little things that most ppl dont consider (diet) that elite athletes stress.