SCAN Symposium 2017: High Fat Diets for Athletes: Time to Abandon High Fat Diets for Athletes - Time to Change Sports Nutrition Guidelines?
During three distinct periods, contemporary sports nutrition guidelines for carbohydrate (CHO)-focused eating for training and competition performance have been challenged by interest in low carbohydrate, high fat (LCHF) diets. Recently, ketogenic (<50 g/d CHO), high fat (80% of energy) diets have been enthusiastically promoted with testimonials of improved sports performance. Indeed, cross-sectional studies of LCHF ultra-endurance athletes show remarkably high fat oxidation rates during moderate intensity exercise. Furthermore, AIS research on elite race walkers found 3 weeks of LCHF greatly enhanced fat utilisation even at high intensities. However, penalties included reduced exercise economy and failure to improve performance after intensified training. Current recommendations for an individualised and periodised approach to CHO availability during training and event- specific optimisation of muscle substrates during competition requires better promotion. Nevertheless, there may be some scenarios where LCHF diets are of benefit, or at least are not detrimental, for sports performance.