Do Strategic Carbs work?
This study took a look at the strategic carbs strategy (Louise Burke. Fat adaptation and glycogen restoration for prolonged cycling—recent studies from the Australian Institute of Sport. Australian Journal of Nutrition and Dietetics, vol. 58, no. 2, 2001, p. S23+). The study looked at:
… a period of exposure to high fat, low CHO intake, followed by the restoration of muscle glycogen stores with a high CHO diet.
Such ‘dietary periodisation’ aims to enhance the capacity of both glycolytic and lipolytic systems to oxidative metabolism during prolonged exercise, by increasing the contribution from fat to substrate metabolism while potentially sparing intact muscle glycogen stores
Here are the results:
The fat adaptation diet caused major changes in fuel utilisation during sub-maximal exercise, with at least some of the adaptations persisting on day seven, even in the face of a plentiful CHO supply. As dramatic as these metabolic changes were, they failed to improve the performance of the cyclists’ time trial.
Together with other research, this study fails to find evidence that fat adaptation strategies offer any benefits for the endurance athlete.
The only remaining question is whether there are any advantages for ultra-endurance athletes who compete in events undertaken at a lower intensity and for longer periods (e.g. four hours or more). For these athletes, fat is the predominant fuel source.