Research Shows Skipping Breakfast Can Hurt Your Performance Later in the Day

Selene Yeager
·2 min read
Photo credit: Arx0nt - Getty Images
Photo credit: Arx0nt - Getty Images

From Bicycling

  • Skipping your morning meal, even if you eat a bigger lunch, can hurt your exercise performance later in the day, according to a small study of highly trained cyclists.

  • The riders also burned less fat and more carbohydrates on the days they fasted in the morning compared to the days when they ate breakfast. The ride also felt harder when they were fasted.

  • Intermittent fasting may help with weight loss, but when you need to perform that day, eat your morning meal.

Research shows that intermittent fasting—also known as time-restricted eating, when you eat in a limited “window” of hours—can help some people lose weight, lower inflammation, and reduce the risk for diseases like diabetes. But when it comes to your cycling performance, opening 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, researchers asked a small group of highly trained cyclists to either skip breakfast or eat breakfast as usual before performing a 20K 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 fasted days, the cyclists skipped breakfast and ate their first meal at noon, taking in about 1,450 calories (the same amount as when they ate breakfast, too, just in one meal). Both days, the cyclists ate high-carb meals, with about 81 percent of their calories coming from carbohydrates, 6 percent from fat, and 13 percent from protein.

Eating breakfast helped the cyclists perform significantly better in the 20K TT later in the day. On the days they ate in the morning, the riders’ mean power output was 9 watts higher and they finished 3 percent (38 seconds) faster. The riders also burned less fat and more carbohydrates (which is the opposite of what riders may be going for when they practice intermittent fasting) for fuel during the TT on the days they fasted till noon. The TT also felt harder during the first 2500 meters on the days they skipped breakfast.

More research is needed to tease out what’s behind these findings. The researchers speculated that nutrient timing could influence how much muscle and liver glycogen is available later in the day, or it could be that starting the day with a morning meal just psychologically sets you up for success.

Whatever the case, even if you use intermittent fasting as a weight loss tool, eating your morning meal is a good strategy for performing your best later that day.

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