Resting metabolic rate fluctuations across the menstrual cycle: a systematic review

Introduction: The aim of this systematic review was to evaluate the current evidence regarding resting metabolic rate fluctuations across menstrual cycle phases in healthy, naturally menstruating females. Methods: A systematic search was conducted in the PubMed and Web of Science databases for articles published from January 2020 to September 2025. Of the 331 records identified, seven studies met the eligibility criteria and were included. Results: Five studies reported a trend toward an elevated metabolic rate during the luteal phase, with four reporting statistically significant increases. The estimated increase ranged from approximately 30 to 120 kcal/day. Conclusion: However, the magnitude of this physiological shift appears to be small (approximately 3-5%) and may overlap with typical day-to-day biological variability, methodological limitations, or measurement error, potentially contributing to inconsistent findings across studies. Future research should prioritise longitudinal, repeated-measures designs with confirmed ovulation to accurately quantify menstrual cycle-related metabolic fluctuations.