Yesterday, Novak Djokovic reached the 19th grand slam final of his career. The Serb will play either Andy Murray or Milos Raonic in Sunday’s final with few likely to bet against the world number one, such is the form he is in. He looks as close to unbeatable as it is possible for a tennis player to ever get.

Yet just a few years ago, this scenario was unthinkable. Back then, Djokovic was widely regarded as a talented but fragile player. He lacked the mentality to become one of the real greats, or so many thought. How wrong those predictions were; his 2011 season was one of the greatest that tennis has ever seen and last year was even better. He now has ten grand slam titles to his name and looks odds-on to add many more.

Djokovic attributes his astonishing improvement to one thing in particular; switching to a gluten-free diet. In 2010, the Serb altered his eating habits drastically, cutting gluten out completely. Gluten is a mixture of proteins found in wheat, rye and barley and acts as a glue that holds food together and is mainly found in bread, pasta and cereals.

Gluten-free diets are not uncommon- those with coeliac disease must follow a gluten-free diet- but over the past decade, it has become increasingly common for individuals to go gluten-free of their own volition. There has also been a marked increase in the number of elite athletes who have cut gluten out of their diets, believing it to be the devil ingredient that was hampering their performance; a study conducted last year found that 41% of a group of 1000 Australian athletes were following a gluten-free diet. So when Djokovic revealed that omitting it was at the root of his improvement, it only strengthened the fast-spreading belief that going gluten-free was the way forward.

It has been claimed by some that gluten can contribute to breathing problems, inflame joints, cause water-retention which leads to weight, cause inflammation in the muscles which can contribute to reduced strength and energy production and finally, prevent recovery, all of which could severely impair an elite athlete’s performance. But a few weeks ago, a study was published in the Medicine & Science in Sports & Exercise journal which found that going gluten-free does not produce the benefits that many athletes had believed.

The study involved 13 competitive cyclists who had no known gluten intolerances. The trial was conducted over two weeks- for one week, all of the athletes followed a gluten-free diet, for the other week, some, unbeknown to them, ate gluten-free and some did not thanks to an identical sports bar, one variation of which contained gluten, the other did not. The athletes trained as normal and noted how they felt.

At the conclusion of the trial, the study found that there was no significant difference in either the athletes’ performances or how they felt. This was a short-term study so further research would need to be done into the longer-term effects of gluten on elite athletes but regardless, that this study quashed the belief that going gluten-free can be immediately life-changing for athletes is interesting. It suggests that the hype around gluten-free diets is hugely disproportionate to the scientific evidence.

Irene Riach, Senior Performance Nutritionist at the Sportscotland Institute of Sport, is wary of recommending to Scotland’s top athletes that they should go gluten-free. “If you’re not coeliac then going on a gluten-free diet might, in the short-term, make you feel slightly less bloated but if you’re not going to put those food groups back into your diet in a safe manner then you’re actually at risk of losing out on some important micro-nutrients,” she explained. “Long-term, you’re actually likely to do damage rather than have any kind of positive effect. Elite athletes’ training really takes its toll on the body and so if you go gluten-free for the long-term, the wheels are likely to come off.”

What this study also shows is that athletes, even the world’s top athletes, are just as susceptible to gimmicks as the rest of us. They are looking for something that might give them that all important edge, whether there is any proof or not that it works. And going gluten-free isn’t the only non-proven fad to pervade sport; there was the breathing strips that allegedly improved air flow into the lungs; the full-body running suit that Cathy Freeman wore at the Sydney Olympics which was intended to make her more aerodynamic; the Power Balance Bands- the rubber bracelets which supposedly help with balance; and the compression sleeve, like the one Milos Raonic wears on his serving arm to compress his muscles, none of which are scientifically proven to work. But more than anything, these fads and gimmicks perhaps show the power of the mind.

It proves that whether it’s the result of a placebo effect or not, if an athlete believes something is working then more often than not, it will. And this has turned Djokovic from a good player into one of the greatest ever.