This is a geat piece from Dr John Briffa about Wimbledon Champion Novak Djokovic changing his diet recently and attributing his success, in part at least, to eliminating wheat and gluten from his diet.
I can confirm that from working with elite athletes many come back with food intolerances to gluten, but also diary, soy and eggs. once people eliminate these from the diet things start to improve especially body fat levels and recovery from games / performance.
The biggest problem with sports nutrition is carb loading. People and athletes think they need to carb load for everything, but this is simply not the case.
Now the research does suggest that carbs improve performance, but you have to ask who funded these studies? Lucozade? I can confirm from the athletes that i work with that reducing carbs does not impeed perfoamnce. Even the triathletes i have worked with do not suffer from eating less carbs (as long as they eat the right carbs at the right times).
Read here about my philosophy towards sport nutrition and elite athlete performance