
We constantly get asked questions about fasted running, so here’s my take on it!
Firstly what is it?
Fasted training is when exercise is performed without prior food intake. It has been explored for its potential to enhance fat oxidation in runners and it is often ‘promoted’ on social media by so-called running experts (not necessarily nutritionists).
What does the research say?
Research indicates that while exercising in a fasted state can increase the body’s reliance on fat as a fuel source during low-intensity activities, this does not necessarily translate to improved endurance performance. A study published in the European Journal of Sport Science found that omitting a carbohydrate-rich breakfast impaired evening endurance exercise performance, despite compensating calorie intake at lunch. What’s even more interesting is the omission also led to decreased fat oxidation during exercise, countering the intended effect of fasting.
In addition to this, a review in the British Journal of Nutrition concluded that overnight fasting before exercise increases lipolysis (fat breakdown) BUT reduces performance in prolonged exercise sessions exceeding 60 minutes. Not exactly the performance benefits we’re looking for right?
So what is this telling us?
While fasted training may elevate fat oxidation during certain activities, current evidence DOES NOT support significant benefits for endurance performance in runners. And here’s the most important part for me as a coach ….
The research also shows that it may lead to decreased exercise capacity and increased perceived effort – meaning runners feel like they are trying harder and aren’t able to train as much AND/OR as effectively.
Therefore before you jump into a fasted diet, because the new social media star said that was the right thing to do, consider speaking to a nutritionist first. The cheaper option is to stick to a healthy balanced diet, train smart, and train fuelled!! Fuel us your friend. Consistent training is still the most effective way to train fat oxidation, so keep aiming for that consistency with your training.
“This post has been written by NLC Co-Founder and head Ultra/Trail Coach Lewis Moses. Lewis continues to coach ultra trail runners of all abilities and has supported athletes to international honours as well as multiple UTMB World Series podiums”.