In recent days, we've seen a lot of confusion surrounding intermittent fasting, as it's being portrayed as a dangerous diet rather than a healthy eating style. Science shows that intermittent fasting, also known as time-restricted eating, where you eat within a limited window of time, can help with weight loss, reduce inflammation, and lower the risk of diseases like diabetes. But when it comes to your athletic performance, opening up that eating window and making room for your morning meal is the way to go, according to a study published in the European Journal of Sport Science.
In the study, the researchers asked a small group of highly-trained cyclists to skip breakfast or eat breakfast as usual before undertaking a 20km time trial in the evening.
On non-fasting days, the cyclists consumed about 580 calories between 8 and 9 a.m. and about 875 calories at lunch. On fasting days, the cyclists skipped breakfast and ate their first meal at noon, taking in around 1.450 calories (the same amount as when they ate breakfast too, in just one meal). Both days, the cyclists ate high-carb meals, with about 81 percent of their calories coming from carbs, 6 percent from fat, and 13 percent from protein.
Can intermittent fasting improve training performance?
Eating breakfast helped cyclists perform significantly better in the 20K later in the day. On the days they ate breakfast, the cyclists' average power output was 9 watts higher , and they finished 3 percent (38 seconds) faster. The cyclists also burned less fat and more carbohydrates (the opposite of what cyclists might aim for when practicing intermittent fasting) for fuel during the workout on the days they fasted until midday. The race also felt harder during the first 2500 meters on the days they opted for intermittent fasting.
More research is needed to uncover what's behind these findings. Researchers speculated that the timing of nutrients could influence the amount of muscle and liver glycogen available later in the day, or it could be that starting the day with a morning meal simply prepares you psychologically for success. In my own experience, training without breakfast leaves me feeling lighter and more powerful.
Whatever the case, even if you're using intermittent fasting as a weight loss tool, eating breakfast before training is a good strategy for performing at your peak later in the day.