What question did this study set out to answer?

To assess the impact of low-carbohydrate high-fat versus high-carbohydrate low-fat diets on glucose metrics in trained cyclists.

February 2, 2026Open Access

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

Key Points

To assess the impact of low-carbohydrate high-fat versus high-carbohydrate low-fat diets on glucose metrics in trained cyclists.
Randomized crossover design involving 15 trained male cyclists
Each participant followed low-carbohydrate high-fat and high-carbohydrate low-fat diets for 7 days
Continuous glucose monitoring technology used to collect glucose data.
Primary outcomes included mean glucose levels, glycemic variability, and nocturnal glycemia.
LCHF diet significantly reduced mean glucose levels compared to HCLF diet.
Glycemic variability was lower on the LCHF diet.
Mean glucose values were higher during exercise regardless of diet.
Nocturnal glycemia was lower following exercise days, indicating the effect of physical activity on glucose regulation.
Considerable individual variability in glucose responses was noted, suggesting the need for tailored dietary strategies.

Abstract

ABSTRACT 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.

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