For the normal person who works out a few times a week and then sits at a desk 40 hours, I think removing grains would be very helpful.
A professional marathoner is a different story. Grains might make sense because of their carb density.
Maybe they're out there somewhere, but I'm pretty sure if you find me one I'll find you a better professional athlete who eats grains.
Find me a (former) professional athlete who lived in perfect health till their 90s.
Maybe they're out there somewhere, but I'm pretty sure if you find me one I'll find you multiple (former) professional athletes who died from CVD, cancer etc.
if cutting out grains would improve fitness in any meaningful way then we'd know about it by now. If Lance Armstrong or
Um, the guy who got cancer when he was 25 years old? Phenomenal athlete, but hardly a good example of a perfectly healthy person.
Find me a professional athlete on a grain-free diet.
Maybe they're out there somewhere, but I'm pretty sure if you find me one I'll find you a better professional athlete who eats grains.
With so much effort put into finding optimal diets for athletes nowadays, if cutting out grains would improve fitness in any meaningful way then we'd know about it by now. If Lance Armstrong or Usain Bolt could go faster with a grain-free diet they'd be doing it.
edit: I found a link about Usain Bolt's diet. Turns out he eats quite a lot of rice:
http://dailyrunningtips.com/training/usain-bolt-diet-food/
Now I can't prove he wouldn't be even faster if he cut out the rice, but I am pretty sure it can't be doing him too much harm.