In the lead up to an important endurance event or a high intensity ‘stop and go’ sporting match lasting more than 90 minutes, it’s possible to elevate glycogen stores to even higher than normal levels, which can significantly improve performance, through a process called carbohydrate loading. Years ago, athletes used to do this by first depleting glycogen stores through an exhaustive bout of exercise followed by a very low carbohydrate diet for three days, and then three days of a high carbohydrate diet. This was found to be effective at achieving ‘super-compensation’ of muscle glycogen stores, above those found even on a regular high-carbohydrate diet. But it’s no longer recommended because of the negative side effects during the low carbohydrate phase, such as weakness, irritability, food cravings, and increased susceptibility to infection: it’s just not worth the discomfort and increased risk of illness, especially before an important event.
Evidence shows that the ‘super-compensation’ of glycogen stores can still be achieved without the prior depletion stage. So, current protocols instead suggest leaving out the depletion stage, but reducing your training and consuming a very high carbohydrate diet for up to three days before competition. The carbohydrate intake during this time can be as high as 70% of total calories, or anywhere between 7-12g per kg of body weight a day, i.e. 560-960g of carbohydrate per day for an athlete weighing 80kg. This takes some effort, and is much more than simply having a big bowl of pasta the night before a race (as many people believe carbohydrate loading to be). Fat and protein intake will likely have to be lowered during this time to ensure overall caloric intake isn’t excessive, and some athletes benefit from emphasising non whole-grain options (white rice, white pasta, white bread, peeled potatoes etc) to prevent higher than usual fibre intakes.