The influence of a low carbohydrate high fat diet on exercise and performance

Current and long standing nutrition guidance in the UK and most other countries advocate that carbohydrates are essential for the maintenance of health and especially for any individual engaging in regular physical activity or sport performance. The current recommendations are that approximately 60-85% of total calories comprise carbohydrates based on wholemeal and wholegrain starchy foods with additonal sugars advocated for competing athletes before, during and even after exercise in the form of energy rich carbohydrate drinks and gels. However, there is a growing body of research arguing that high carbohydrate diets could contribute to non-communicable diseases such as obesity and type 2 diabetes and the importance of carbohydrates for exercise performance are exaggerated.

The use of carbohydrate restricted diets within the field of sport, exercise and nutrition is a controversial topic. Reducing carbohydrate intake while mainitng a eucaloric diet means increasing the amount of fat in the diet and there is notable resistance from many who follow the doctrine that fat is bad and this is often cited as the cause for morbidity. Moerover, recent research is equivocal in their findings on the efficacy of reduced carbohydrate diets. Indeed, the effects of low carbohydrate diets for health and exercise performance is hampered by research which has used large differences in levels of carbohydrate restriction (<20-150g per day), short duration studies which do not allow keto adaptaion to take place, or they experienced limited adherence to restrictive intakes among participants. There are also many poorly conducted studies which appear to be designed to specifically debunk the low carbohydrate theory rather than test it.

We therefore seek to explore the impact of a ketogenic diet (<20-50g carbohydrate daily for 2-12 weeks) and low carbohydrate diets (<130g carbohydrate daily for 2-12 weeks) on the health and physiological responses to endurance and/or power athletes. It is envisaged that this project will examine the physiological responses to the restriction of carbohydrates (keto adaptation), measure the duration effect of restrictions and also the efficacy and timing of using carbohydrate supplements. Ultimately, we would like to explore whether the responses to a low carbohydrate high fat diet can be impactfull to exercise performance and also whether there is a synergy for carbohydrate supplements while in a keto-adapted state.