The Effects Of A Ketogenic Diet On Exercise Metabolism And Physical Performance In Off Road Cyclists(1)

This study examined how a ketogenic diet (very low carb, high fat) affects exercise performance and metabolism in eight experienced off-road cyclists. Each participant followed both a standard mixed diet and a ketogenic diet rich in healthy polyunsaturated fats for extended periods, with researchers testing their cycling performance and measuring various health markers after each dietary phase.

The ketogenic diet produced several notable changes in the cyclists' bodies and performance. Participants lost body weight and fat mass while following the ketogenic approach. Their blood lipid profiles also improved. Interestingly, some measures of aerobic fitness actually increased on the ketogenic diet - specifically, their maximum oxygen uptake and oxygen uptake at lactate threshold (the point where muscles begin to fatigue) went up when measured relative to their new lower body weight.

However, the study revealed important trade-offs. While the cyclists became more efficient at burning fat for fuel (shown by lower respiratory exchange ratios), their maximum power output and power at lactate threshold were actually higher when following the mixed diet. This suggests that while ketogenic diets can improve fat-burning capacity and certain fitness metrics, they may compromise peak power performance. The cyclists' bodies also had to work harder at rest and during easier exercise intensities while in ketosis, requiring more oxygen and showing higher heart rates.

For patients interested in metabolic health, this research highlights that ketogenic diets can effectively promote fat loss and improve fat-burning capacity, but may involve performance trade-offs depending on exercise goals. At VALIA Health, we help patients evaluate whether ketogenic approaches align with their individual health objectives and activity levels.