Several people asked me to comment on this article. Seeing it received a lot of media attention, I've decided to write it publicly.
Many people try to copy habits of professional athletes in order to pave their way towards sports success. Many of these are compulsive actions and superstitious rituals that don't have a significant influence on sports success, other than a sense of control. Even though that is a very important factor, I believe it to be of significance only on a top level of performance.
Novak Djokovic stopped consuming food items containing gluten as well as dairy products, and he felt an amazing improvement in all aspects of health. Even though I believe he exaggerates a little, does that mean everyone needs to do the same?
„Chemical test later showed a huge intolerance for grains and dairy“. Djokovic apparently has a very big intolerance for gluten and lactose, even though we don't know what kind of a „chemical test“ it was. So, in his case there's a physiological reason why he sees the improvement following this type of diet. However, most people don't have the same grounds for this. If there's no celiac disease on gluten/lactose sensitivity present, getting rid of these food items won't have a positive influence on health, and can strip you of essential nutrients.
As Djokovic says in his book, you can try to stop eating these food items for a certain period of time and track any changes that might occur. However, there are three traps here.
First one is the power of auto-suggestion – you enter an experiment confident you'll feel a change for the better. In the end you do and you think it's because of the changed variable, but often this feeling or an actual physical change is only in your mind. I don't want to go into details because I don't know enough about psychology, but I think you got the point.
Second trap is an unconscious change in other variables which would lead to a positive change in themselves or combined with the first one. Once again you attribute this change to the original variable, but it's equally possible the side-variables might be the ones to blame. It's impossible to tell which variable is the one, except in a controlled scientific study. Which is why these exist.
Third trap is not providing your body with items of same nutritive value as the ones you removed from your diet. That's especially visible with milk and dairy products, which are by far the best, not to say one-of-a-kind, sources of calcium in human diet.
So, feel free to experiment, but bear in mind these traps, and as with any other dietary intervention, don't expect miracles.