Exercising in a fasted state increases fat loss compared with exercising after eating.

Is it true that exercising in a fasted state increases fat loss compared with exercising after eating?

Partly. A meta-analysis and several trials report that fasted aerobic exercise raises fat oxidation or lipid availability compared with fed exercise, but a 2024-2025 review notes that burning more fat during a session does not necessarily mean greater overall body fat loss, and one small trial found no increase in whole-body fat oxidation. The retrieved evidence addresses metabolic markers rather than measured fat loss, so it only partially covers the claim.

Verdict: CONTESTED PARTIAL · 3 sources for, 2 against · Last checked 2 Oct 2026

The private library was unavailable for some searches in this check. Missing library results are not evidence against the claim.

Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis. (n.d.). cir.nii.ac.jp. https://doi.org/10.1017/s0007114516003160

What happens to your body when you work out before you eat | National Geographic. (n.d.). nationalgeographic.com. https://www.nationalgeographic.com/health/article/fasting-exercise-health-benefits

Aird, T. P., Davies, R. W., & Carson, B. P. (2018). Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis.. doi.org. https://doi.org/10.1111/sms.13054

Iwayama, K., Kawabuchi, R., Nabekura, Y., Kurihara, R., Park, I., & Kobayashi, M. (2017). Exercise before breakfast increases 24-h fat oxidation in female subjects. doi.org. https://doi.org/10.1371/journal.pone.0180472

Postexercise skeletal muscle signaling responses to moderate- to high-intensity steady-state exercise in the fed or fasted state. (n.d.). cir.nii.ac.jp. https://doi.org/10.1152/ajpendo.00311.2018