Endurance is the cornerstone of road cycling. Whether you're participating in a gruelling sportive or aiming for a personal best in a time trial, the type of fuel your body uses can be a game-changer. While carbohydrates have traditionally been the go-to energy source for cyclists, an emerging body of evidence suggests that burning fat before carbohydrates can offer several advantages.

This article delves deeper into the science behind this approach and explores the ongoing debate in the athletic community.

Adapting muscles to burn fat for fuel will help you achieve greater distances

The Fat-Burning Process & The Science of Fat as Fuel

Fat is an incredibly energy-dense macronutrient. Unlike carbohydrates, which are stored in limited quantities in the muscles and liver as glycogen, fat stores are almost unlimited, even in the leanest of athletes. When you engage in lower-intensity exercise, your body prefers to burn fat. According to this article, High-fat versus high-carbohydrate diets for optimal higher intensity endurance exercise performance: and the winner is… published in The Journal of Physiology, this is because fat oxidation requires a significant amount of oxygen, and oxygen is more readily available when you're not pushing your limits.

Training Adaptations

Training your body to use fat as a primary fuel source involves specific endurance training in lower training zones. This type of training encourages your muscles to both transport and burn fats more efficiently. Some athletes have even incorporated training in a fasted state to enhance the effects of fat utilisation. When carbohydrate availability is low, the body tries to conserve its glycogen stores, leading to a sparing of muscle glycogen and, in the long term, increases in the enzymes and proteins involved in the transport and use of fats within the muscle, according to the research paper, Dietary Manipulations Concurrent to Endurance Training  published on Pub Med.

Metabolic State, Flexibility, and Muscle Adaptation

Metabolic flexibility refers to the body's ability to switch between fat and carbohydrates for fuel efficiently. When you train your body to burn fat effectively, your muscles adapt to use more fat and less carbohydrate at any given intensity. This adaptation is not just beneficial for endurance; it's a sign of a healthy, well-functioning metabolism, according to the paper We are what we eat? Eating ‘against the grain’ may not be as beneficial to performance and ‘economy’ in endurance athletes published in The Journal of Physiology.

Advantages of Fat Burning in Long-Distance Cycling

This metabolic flexibility has several advantages, especially for long-distance road cycling. It delays the depletion of muscle and liver glycogen stores, thus preventing the dreaded 'bonk' or 'hitting the wall' scenarios. This is particularly crucial for long events like sportives, where preserving your glycogen stores for higher intensity efforts can significantly improve your performance.

The Debate: Carbs vs Fat

The topic of whether to use carbs or fat for fuel has become a polarising issue in the athletic community. While some athletes and trainers are staunch advocates of Low Carb, High Fat diets (LCHF), others argue that carbohydrates are irreplaceable for high-intensity performance.

Current Research Insights

Recent research suggests that although LCHF diets can enhance the body's ability to burn fat and spare glycogen stores, they do not necessarily translate into real-world performance gains. Studies on elite marathon runners found that while their ability to burn fat improved, it did not lead to any significant performance improvements. Moreover, the metabolic changes triggered by a LCHF diet came at the expense of efficiency and blunted top-end speed and power. See the research paper, Competition Nutrition Practices of Elite Ultramarathon Runners published on Pub Med.

Individual Variability

However, it's worth noting that individual responses to different dietary approaches can vary significantly. Some athletes may find that they perform better on a LCHF diet, while others may experience a decline in performance. This variability underscores the importance of personalised nutrition and training plans.

Training your body to prioritise fat over carbohydrates offers several advantages, particularly for long-distance road cycling. It can improve your endurance, delay the onset of fatigue, and contribute to metabolic flexibility.

In fact, Michael DePalmer, utilised SportActive's Enduro Booster as part of his training programme that saw him crowned Texas State Road Race Champion in 2023.

Michael utilised SportActive's Enduro Booster training to become a champion

However, this approach needs to be balanced with carbohydrates for high-intensity efforts. Given the ongoing debate and individual variability in responses, consulting professionals for personalised advice is a good idea.

Keep cycling, The SportActive Team.

Submitted: 12/10/23