Fasting before evening exercise reduces net energy intake and increases fat oxidation, but impairs performance in healthy males and females

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Slater, T ORCID: https://orcid.org/0000-0003-2764-3148, Mode, WJA ORCID: https://orcid.org/0000-0003-4667-2876, Pinkney, MG, Hough, J ORCID: https://orcid.org/0000-0001-6970-5779, James, RM ORCID: https://orcid.org/0000-0002-7119-3159, Sale, C, James, LJ and Clayton, DJ ORCID: https://orcid.org/0000-0001-5481-0891, 2022. Fasting before evening exercise reduces net energy intake and increases fat oxidation, but impairs performance in healthy males and females. International Journal of Sport Nutrition and Exercise Metabolism. ISSN 1526-484X

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Official URL: https://doi.org/10.1123/ijsnem.2022-0132

Abstract

Acute morning fasted exercise may create a greater negative 24-hr energy balance than the same exercise performed after a meal, but research exploring fasted evening exercise is limited. This study assessed the effects of 7-hr fasting before evening exercise on energy intake, metabolism, and performance. Sixteen healthy males and females (n = 8 each) completed two randomized, counterbalanced trials. Participants consumed a standardized breakfast (08:30) and lunch (11:30). Two hours before exercise (16:30), participants consumed a meal (543 ± 86 kcal; FED) or remained fasted (FAST). Exercise involved 30-min cycling (∼60% VO2peak) and a 15-min performance test (∼85% VO2peak; 18:30). Ad libitum energy intake was assessed 15 min postexercise. Subjective appetite was measured throughout. Energy intake was 99 ± 162 kcal greater postexercise (p < .05), but 443 ± 128 kcal lower over the day (p < .001) in FAST. Appetite was elevated between the preexercise meal and ad libitum meal in FAST (p < .001), with no further differences (p ≥ .458). Fat oxidation was greater (+3.25 ± 1.99 g), and carbohydrate oxidation was lower (−9.16 ± 5.80 g) during exercise in FAST (p < .001). Exercise performance was 3.8% lower in FAST (153 ± 57 kJ vs. 159 ± 58 kJ, p < .05), with preexercise motivation, energy, readiness, and postexercise enjoyment also lower in FAST (p < .01). Fasted evening exercise reduced net energy intake and increased fat oxidation compared to exercise performed 2 hr after a meal. However, fasting also reduced voluntary performance, motivation, and exercise enjoyment. Future studies are needed to examine the long-term effects of this intervention as a weight management strategy.

Item Type:	Journal article
Publication Title:	International Journal of Sport Nutrition and Exercise Metabolism
Creators:	Slater, T., Mode, W.J.A., Pinkney, M.G., Hough, J., James, R.M., Sale, C., James, L.J. and Clayton, D.J.
Publisher:	Human Kinetics
Date:	28 September 2022
ISSN:	1526-484X
Identifiers:	Number Type 10.1123/ijsnem.2022-0132 DOI 1604396 Other
Rights:	Accepted author manuscript version reprinted, by permission, from International Journal of Sport Nutrition and Exercise Metabolism, 2022, https://doi.org/10.1123/ijsnem.2022-0132 © Human Kinetics, Inc.
Divisions:	Schools > School of Science and Technology
Record created by:	Laura Ward
Date Added:	29 Sep 2022 14:23
Last Modified:	29 Sep 2022 14:23
URI:	https://irep.ntu.ac.uk/id/eprint/47159