Science has debated the optimal diet for performance and health for decades. A study published in Frontiers in Nutrition explored the effects of high-carbohydrate, low-fat diets versus low-carbohydrate, high-fat diets on middle-aged male athletes. The study assessed the impact of each diet on performance and various health biomarkers.
Performance:
- High-Carb Diet: Traditionally recommended for athletes to replenish glycogen stores. The study found that athletes on high carb diets maintained high-intensity exercise performance comparable to those on low carb diets.
- Low-Carb Diet: Athletes on low carb diets exhibited similar performance levels in both one-mile time trials and repeated sprints, challenging the notion that high-carb intake is essential for maintaining high-intensity exercise capacity.
Fat Oxidation:
- High Carb Diet: Lower rates of fat oxidation were observed, consistent with the reliance on carbohydrates for energy during high-intensity activities.
- Low Carb Diet: Showed significantly higher peak fat oxidation rates, even at higher intensities (up to 86.4% VO2 max), indicating an enhanced capacity for fat utilization.
Glucose and Insulin Response:
- High Carb Diet: Athletes displayed higher mean and median glucose levels, Despite a high training volume, some of these athletes still showed glucose levels associated with prediabetes.
- Low Carb Diet: Resulted in lower and more stable glucose levels, suggesting improved glycemic control and better insulin sensitivity.
Cardiometabolic Health:
- High Carb Diet: Associated with stable but higher glucose variability, potentially increasing the risk of metabolic complications.
- Low Carb Diet: Demonstrated improvements in several cardiometabolic markers, including reduced glucose variability and lower inflammation markers.
While both dietary strategies can support high-intensity athletic performance, low carb diets may offer additional benefits in terms of fat oxidation and glycemic control, which may be especially useful for older athletes, especially those at risk for metabolic diseases like diabetes.
