If you’re in the habit of eating breakfast before exercising in the morning, you may want to reconsider the order in which you start your day as there are significant benefits to exercising in a fasted state.
A common belief is that you need to eat breakfast to optimize exercise performance. While there’s evidence to support this stance,1 other evidence suggests you can reap important health benefits by exercising in a fasted state.
Fasted Exercise Curbs Food Intake and Improves Cognition
Research2,3 published in the August 2019 issue of The Journal of Nutrition found that skipping breakfast before exercise helps curb food intake for the remainder of the day, resulting in an overall energy deficit — in this case averaging 400 calories per day.
Earlier research,4 published in 2015, found that women who skipped breakfast and worked out on an empty stomach had better working memory in the midafternoon and reported less mental fatigue and tension later in the day than those who ate breakfast (in this case a cereal-based meal) before exercising.
Fasted Exercise Boosts Fat Loss
Fasted exercise has also been shown to be particularly helpful for fat loss — it essentially forces your body to shed fat. The reason for this is because your body's fat burning processes are controlled by your sympathetic nervous system (SNS), and your SNS is activated by exercise and lack of food.
The combination of fasting and exercising maximizes the impact of cellular factors and catalysts (cyclic AMP and AMP kinases) that force the breakdown of fat and glycogen for energy. A 2012 study5 confirmed that aerobic training in a fasted state lowered both total body weight and body fat percentage, while exercising in a fed state decreased body weight only.