Fasted training

Fasted training is often used as a tool to increase fat loss. What does the research on fasted training show?
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📚 A 2014 study compared the effects of fasted VS fed cardio while matching the daily calorie and macronutrient intake of the participants. Both groups lost a similar amount of fat [1]. As the researchers point out, the human body constantly adjusts its fuel source. If your body uses more fat for energy during fasted training in the morning, you burn less fat later in the day once you eat more calories. The only way fasted training can boost fat loss is if training fasted helps you reduce your daily calorie intake [2].
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🏋‍♂️ Now, when it comes to strength performance, a 2019 study found that people who are used to having breakfast tend to perform worse in their training when they have a fasted workout [3]. So if you normally eat something before training, working out fasted likely harms your performance. Future research will have to investigate whether we can get accustomed to fasted training. It is possible that as you consistently train fasted, your body gets used to performing in a fasted state and there is no performance detriment. But as mentioned, there is no research on this to date.
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The way I would see fasted training is as another tool in your “fat loss toolbelt”. If for any reason you like training in a fasted state, it’s worth pursuing. But if you dislike the idea of training fasted, you are not missing out on any fat loss benefits by training in a fed state, as long as you make sure you stay in the same calorie deficit.
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Scientific References:
1. Schoenfeld, B. J., Aragon, A. A., Wilborn, C. D., Krieger, J. W., & Sonmez, G. T. (2014). Body composition changes associated with fasted versus non-fasted aerobic exercise. Journal of the International Society of Sports Nutrition, 11(1), 54.
2. Edinburgh, R. M., Hengist, A., Smith, H. A., Travers, R. L., Betts, J. A., Thompson, D., … & Tipton, K. D. (2019). Skipping breakfast before exercise creates a more negative 24-h energy balance: A randomized controlled trial in healthy physically active young men. Journal of Nutrition.
3. PMID: 30707135