Keto-adaptation enhances exercise performance and body composition responses to training in endurance athletes.
Background. Low-carbohydrate diets have recently grown in popularity among endurance athletes, yet little is known about the long-term (>4 wk) performance implications of consuming a low-carbohydrate high fat ketogenic diet (LCKD) in well-trained athletes.
Methods. Twenty male endurance-trained athletes (age 33 ± 11 y, body mass 80 ± 11 kg; BMI 24.7 ± 3.1 kg/m2) who habitually consumed a carbohydrate-based diet, self-selected into a high-carbohydrate (HC) group (n = 11, %carbohydrate:protein:fat = 65:14:20), or a LCKD group (n = 9, 6:17:77). Both groups performed the same training intervention (endurance, strength and high intensity interval training (HIIT)). Prior to and following successful completion of 12-weeks of diet and training, participants had their body composition assessed, and completed a 100 km time trial (TT), six second (SS) sprint, and a critical power test (CPT). During post-intervention testing the HC group consumed 30–60 g/h carbohydrate, whereas the LCKD group consumed water, and electrolytes.
1.13 min·s, LCKD −4.07 min·s, P = 0.057, ES: 0.196). SS sprint peak power increased by 0.8 watts per kilogram bodyweight (w/kg) in the LCKD group, versus a −0.1 w/kg reduction in the HC group (P = 0.025, ES: 0.263). CPT peak power decreased by −0.7 w/kg in the HC group, and increased by 1.4 w/kg in the LCKD group (P = 0.047, ES: 0.212). Fat oxidation in the LCKD group was significantly greater throughout the 100 km TT.
Conclusions. Compared to a HC comparison group, a 12-week period of keto-adaptation and exercise training, enhanced body composition, fat oxidation during exercise, and specific measures of performance relevant to competitive endurance athletes.
sful self-management of type 2 diabetes.