Document Type


Publication Date




Publication Title

American Journal of Human Biology


Article in Press


e23874 (1-5)


Introduction: Breastfeeding women have elevated resting metabolic rate (RMR); however, whether a single bout of lactation increases RMR is unknown. This study aimed to determine if a single bout of lactation acutely increased RMR.

Methods: Twenty-two lactating women (age: 31 ± 0.9 year, body mass index: 27.3 ± 1.2 kg/m2) were recruited. RMR was assessed at baseline and at 1- and 2-h following breast milk expression.

Results: RMR was unchanged in lactating women following a single bout of lactation (baseline: 1437 ± 39; 1 h: 1425 ± 37 2 h: 1440 ± 31 kcal/day) (p > .05). RMR was not correlated to daily milk produced (r = 0.05, p > .05), but was correlated to body mass (r = 0.74, p < .001), fat-free mass (kg) (r = 0.61, p < .01), and fat mass (kg) (r = 0.71, p < .01).

Conclusion: RMR in lactating women appears to be more related to body mass or composition in the postpartum period rather than lactation.


© 2023 The Authors.

This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Data Availability

Article states: Research data are not shared due to ethical restrictions.

Original Publication Citation

Reynolds, L. J., Powell, K. R., Akhter, T., Twiddy, H. M., & Wilson, P. B. (2023). A single bout of breast milk expression does not increase resting metabolic rate. American Journal of Human Biology, e23874.


0000-0003-0075-2168 (Reynolds), 0000-0003-4052-5023 (Wilson)