Hormonal
Menstrual cycle phase (follicular vs. luteal) and oral contraceptive use (active vs. placebo) do not significantly influence substrate oxidation (carbohydrate and fat ratios) at rest or during moderate-intensity continuous exercise.
You do not need to adjust your carbohydrate or fat intake based on where you are in your menstrual cycle or whether you are on birth control. The science shows that fuel oxidation remains consistent across phases. Focus on consistent nutrition and training intensity rather than trying to 'hack' your cycle for metabolic changes.
A broad review reveals that the differences between the follicular and luteal phases and between OC active and placebo phases are not associated with marked differences in exercise performance and appear unlikely to influence muscular hypertrophy in response to resistance exercise training. A systematic review and meta-analysis of substrate oxidation between MC phases revealed no difference between phases in the relative carbohydrate and fat oxidation at rest and during acute aerobic exercise.
Why this rating
Based on a systematic review and meta-analysis of 55 studies (928 participants) with moderate quality evidence, though GRADE assessment rated certainty as 'very low' due to observational nature.
Source
Menstrual cycle hormones and oral contraceptives: a multimethod systems physiology-based review of their impact on key aspects of female physiology
Alysha C. D’Souza et al. · Journal of Applied Physiology · 2023
DOI 10.1152/japplphysiol.00346.2023
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