The Game Changers, a movie promoting the benefits of a plant-based diet on athlete performance has been gaining a lot of traction. With big sports stars involved like Lewis Hamilton, Novak Djokovic, Arnold Schwarzenegger, Jackie Chan and backed by Hollywood heavy weight director and producer James Cameron one can see why. However, for the uninitiated majority of those involved with this production including the chief science advisor are supporters of plant-based diets, leading to a somewhat biased slant. Therefore, the question needs to be asked “what does the research really say about plant-based diets and athletic performance”.
“love to put Viagra out of business, just by spreading the word on plant-based eating.”
James Cameron – The Independent 25/04/2018
Diets for athletic performance are extremely individualised and are geared towards the specific demands of the athlete and sport the individual competes in. In a very simplistic manner, it requires a balance of protein, carbohydrates and fats to aid with the development of lean muscle mass, energy production and recovery matched against energy expenditure or calories burned throughout the day.
Gluten Free Diets
Athletes are always looking to find that extra edge over their competitors and diet is one area that can be utilized to good effect however, all that glitters may not actually be gold. A few years ago with the explosion of gluten and wheat intolerances and celiac disease a few athletes decided to go gluten free and claimed it was responsible for improving their athletic performance, even though they hadn’t been diagnosed as celiac. Interestingly though these claims aren’t currently supported by the research, with a study in 2015 that took 13 competitive endurance cyclists with no history of celiac disease and compared their time trial performance while on a short term gluten containing diet and on a gluten free diet. The study showed athletic performance didn’t improve for the athletes on a gluten free diet with no history of celiac disease. Given, this study had a small sample size of 13 athletes and was conducted over a short time period (7-day diets) it is however currently the only study comparing gluten free and gluten containing diets on athletic performance in non-celiacs.
Ketogenic diets have been another diet trend amongst athletes, especially in the world of sports like CrossFit. Ketogenic diets are low in carbohydrates and high in fats, which at first glance seems counterproductive to athletic performance when carbohydrates are an athlete’s main source of energy. In the non athletic population Ketogenic diets or low carbohydrate diets have been shown to be beneficial with weight-loss and reductions in the risk of diabetes. One could argue that reducing body mass might be an important goal in endurance and weight based sports however, the current limited literature looking at ketogenic diets and athletic performance does not support the use of ketogenic diets for athletic performance. Although ketogenic diets do not negatively impact performance, they may lead to unwanted decreases in lean body mass or a drop off in skeletal muscle hypertrophy.
As it is becoming quickly evident the current literature investigating diet and athletic performance is sparse and generally low in quality. This trend continues when comparing plant-based diets versus omnivore (animal and plant) diets and athletic performance, especially in the elite athletic population which is the premise of The Game Changers documentary. A search of PubMed found only one review paper which systematically reviewed the current literature comparing vegetarian and omnivore diets with physical performance. The paper included 8 studies, 7 randomised controlled trials and 1 cross-sectional study and found there were no differences in athletic performance between a vegetarian-based diet and omnivore diet.
“As someone who follows a plant-based diet, I believe we need a healthier high street option that tastes amazing but also offers something exciting to those who want to be meat-free every now and again.”
Lewis Hamilton on his Neat Burger company – The Sun 29/08/2019
With such limited and low-quality evidence currently available comparing diets and athletic performance, it is extremely important in this commercial and marketing driven age that we step back and ask questions to understand where the truth lies, rather than letting a documentary “inform” us. Plant-based diets and reducing animal meat intake has been associated with health benefits, with a large section of the research on plant-based diets focusing on its potential risk reduction in chronic preventable diseases such as cardiovascular disease. At present there is limited research available analysing its effects on athletic performance with no known larger scale multi-arm studies comparing a variety of diets on athletic performance. Currently the evidence does not show a positive association between a plant-based diet and athletic performance compared to other animal meat with plant based diets.
Diets for athletes, especially elite athletes are extremely individualised and what works for one athlete might not necessarily work for another. Whatever diet is chosen, plant-based or omnivore it should be driven by a nutritionist, dietitian or health professional with sports nutrition training and be grounded in the best evidence available.