Historically, sports nutrition has been dominated by carbohydrate-centric themes, with key landmarks including the discovery of “carbohydrate (CHO) loading” (glycogen supercompensation) strategies in the 1960s and the development of sports drinks in the 1980s. Contemporary sports nutrition, however, embraces greater complexity in the knowledge and practice of fuelling for training and competition, with the principles of personalisation and periodisation underpinning between- and within-athlete variability in daily CHO intakes. The key metric has shifted from the total CHO intake per se to the concept of “CHO availability”, which assesses the amount and timing of CHO intake in relation to fuel needs of the immediate exercise sessions. When it is important to be able to sustain higher-intensity workloads and other exercise qualities (e.g. technical and tactical requirements), strategies that store adequate muscle and liver glycogen prior to and between sessions and/or provide additional CHO during the session are recommended. There is current interest in the practices of elite endurance athletes in strenuous events (e.g. marathons, ironman triathlons and road cycling stage races) who consume extreme amounts of CHO during competition (hourly rates of 120 g+). Such practices are made possible by the development of special sports products containing CHO with different intestinal absorption characteristics, as well as strategies during training to “train the gut” to increase intestinal tolerance and absorption. Strategies that promote high CHO availability should be undertaken for key training sessions and events, but are less important during lower intensity training sessions. In fact, the recognised role of muscle glycogen stores as a driver of the cellular signalling pathways that underpin the adaptation to endurance exercise mean that some endurance athletes deliberately manipulate training characteristics and dietary CHO intake to allow some sessions to be undertaken as “train low” workouts. A newer interest in the role of glycogen in promoting the release of exerkines and myokines during and after exercise, with downstream effects on a range of body systems should also be considered. Finally, there has been renewed interest in ketogenic low CHO high fat (LCHF) diets as an alternative strategy to promote fat as the primary fuel for endurance exercise. Although such diets can double the contribution of fat oxidation to exercise fuel needs, even during higher intensity exercise, the stoichiometry of ATP producing biochemical pathways favours greater energy production from CHO oxidation from a given oxygen supply, ultimately producing greater speed/power.