Low-Versus High-Carbohydrate Isocaloric Diets on Continuous Glucose Monitoring Metrics in Healthy Trained Cyclists: A Randomized Crossover Trial.

This randomized crossover trial examined the effects of low-carbohydrate high-fat (LCHF) versus high-carbohydrate low-fat (HCLF) isocaloric diets on continuous glucose monitoring (CGM)-derived glucose metrics in trained, healthy male cyclists. Participants (n = 15) followed each dietary condition for 7 days, with glucose data continuously collected using CGM technology. The primary outcomes assessed were mean glucose levels, glucose variability, and time spent within specific glycemic ranges across wake, exercise, and nighttime phases. Results indicated that the LCHF diet significantly reduced mean glucose levels and glycemic variability (CV) compared to the HCLF diet. Mean glucose values were significantly higher during exercise compared to wake and night phases, irrespective of dietary conditions. Exercise intensity was positively associated with higher glucose concentrations during training sessions, independent of dietary conditions. Furthermore, nocturnal glycemia was significantly lower after exercise days, suggesting an influence of prior physical activity on overnight glucose regulation. Substantial interindividual variability in glucose responses was observed, highlighting the necessity of personalized dietary strategies for athletes. This study demonstrates that dietary carbohydrate manipulation significantly influences glucose metabolism, with implications for optimizing training, recovery, and metabolic health in endurance athletes. Future research should further explore individualized glucose responses and longer-term adaptations to dietary interventions in athletic populations.