A 2018 study published by the Nutrients scientific journal shows that a controlled and low carbohydrate intake combined with a high fat intake has a minimal effect on athletic performance. In order to understand this study and its findings, athletes need to comprehend that this idea of controlled macronutrients is not new. The ketogenic diet is seeing a strong rise in popularity, even if it has been strongly criticized when its ideas were first published in 1920. It was believed that the diet can have a positive effect on epilepsy sufferers and today, many people associate the diet with weight loss and in some cases, with improved physical performance.
Research methods and findings
The study was part of a project of Australia's Centre for Sport and Research at Deakin University. It went on to investigate the blood composition of two groups of subjects. The first group followed a diet of low carbohydrates and high fats such as the keto diet while the second group followed a diet high in carbs. All subjects were elite level walkers.
There is a clear indication that the controlled carbohydrate intake doesn't influence peak performance. It is explained by the study which measured the acid-base status in these elite athletes. But what is acid-base status? Measured in pH, acid-base status is the natural balance between acidic and basic alkaline compounds in the blood. The kidneys and the lungs are responsible for the acid-base balance.
Controlled carb intake does not affect the athletic performance of the two groups in the study either due to pre-existing training adaptations or due to the actions of the kidneys and the lungs which directly impact acid-base. Of course, the study found that the differences in the pH levels of the two groups were significant. However, this was not enough to change the acid-base.
The innovation of the study
The research comes to offer new information in an area which was not studied at all. While there are other studies which seek to answer similar questions, they were not focused on elite athletes. It is why the researchers chose top athletes who performed at the Olympic Games or at World Cup championships. Even more, the researchers went to great lengths to ensure all subjects had the supervision of qualified dietitians.
In these conditions, the main conclusion of the study is that over a period of three weeks, the low carbohydrate and high fats diet of the athletes had no influence on acid-base status. This anomaly can be associated with the fact that elite athletes have a different training status than the subjects from previous studies, which were in a healthy state, but not at an athletic. However, it can also be explained by the higher capacity of the body to neutralize dietary acids simply by expulsion either through the respiratory system or through the renal pathways. In other words, changes in athletic performance while on the ketogenic diet are not likely to come from changes in acid-base status.
Source: Nutrients 2018, 10(2), 236; https://doi.org/10.3390/nu10020236