Ever wondered why you're eating more food before your period? We explore how hormones across the menstrual cycle influence energy requirements.
Overview of the menstrual cycle
The menstrual cycle is the hormonal cycle (ranging from 21-35 days) a female body goes through to prepare for pregnancy. It is defined as the time from the first day of a woman's period to the day before the next. Two main hormones, oestrogen and progestorone, flactuate throughout the cycle and cause a variety of symptoms. There are two main phases of the cycle:
The follicular phase (before ovulation): the menstrual bleed/period occurs in the early follicular phase, which is the start of the cycle (day 1). Both oestrogen and progestorone are at their lowest. The average period lasts 2-7 days. By the late follicular phase, oestrogen reaches its peak ahead of ovulation, which typically happens halfway through the cycle (i.e., day 14 of a 28 day cycle).
The luteal phase (after ovulation): in the early luteal phase, oestrogen takes a dip after ovulation, whilst progesterone begins to rise. By the mid luteal phase, porgesterone peaks at its highest and oestrogen is also high. By the end of the luteal phase (late luteal), both hormone decline, ahead of the cycle repeating.
Nutrition requirements across the cycle
Energy intake and expenditure
Oestrogone and progesterone are known to influence physiological processes across the body, including those related to nutritional status. Oestrogen suppresses appetite, whilst progesterone has the opposite effect, especially in the presence of oestrogen. This may result in reduced appetite in the follicular phase (when oestrogen peaks) and increased appetite in luteal phase (when progesterone peaks). (1)
A recent systematic review (a review which brings together all relevant studies) looking at energy intake across the menstrual cycle found increased energy intake during the luteal phase compared with the follicular phase, with an average difference of 168kcal per day. (2) This is partially explained by the need to maintain positive energy balance in order to support a potential pregnancy in the luteal phase. Resting metabolic rate (RMR, the energy used by the body for regular functions at rest) has also been found to increase in the luteal phase by up to 300kcal. (3) This means that at rest, females may burn more calories during the luteal phase than follicular phase.
Metabolism of carbohydrates, fat and protein
Oestrogen reduces the rate of glycogen/ carbohydrate breakdown, promotes breakdown of fat (lipolysis) and increases availability of fatty acids. On the other hand, progesterone increases protein breakdown, especially during the luteal phase. There is supporting evidence that females require more lysine (an amino acid, building block of protein) during the luteal phase. (4) Lysine is found in protein foods, such as meat, diary and tofu. The table below presents a summarises the impact of the menstrual cycle phase on nutritional needs.
Follicular phase | Luteal phase |
Reduced appetite | Increased appetite |
Reduced energy intake | Increased energy intake |
Reduced RMR | Increased RMR |
Reduced glycogen (carb) storage | Increased glycogen (carb) storage |
Reduced fat breakdown | Increased fat breakdown |
Reduced protein breakdown | Increased protein breakdown |
Whilst there is evidence of higher energy requirements during the luteal phase, more research is needed to make generalised recommendations to all women. Across the menstrual cycle, females, especially active females, should aim to ensure adequate energy intake (i.e., eat enough calories), with a particular focus on intake of good quality protein (lean meat, fish, eggs, tofu) and healthy fats (i.e., oily fish, nuts, seeds, olive oil) during the luteal phase.
Summary
There is evidence to suggest an increase in appetite and resting metabolic rate during the luteal phase of the menstrual cycle (before your period), whilst breakdown of protein and fat also increases during this phase.
There is not enough evidence yet to warrant specific guidelines for females on what and how much to eat across each phase of the cycle. The priority, especially for active females, should be to ensure enough intake of calories across the cycle, and a particular focus on good quality protein and healthy fats during the luteal phase.
Phase-related differences in energy intake vary between females and between individual cycles. Each female should track their cycle and symptoms to notice any changes in appetite and cravings.
References
Hirschberg AL. Sex hormones, appetite and eating behaviour in women. Maturitas. 2012;71:248–256.
Jessica A L Tucker, Seth F McCarthy, Derek P D Bornath, Jenna S Khoja, Tom J Hazell, The Effect of the Menstrual Cycle on Energy Intake: A Systematic Review and Meta-analysis, Nutrition Reviews, 2024
Benton MJ, Hutchins AM, Dawes JJ. Effect of menstrual cycle on resting metabolism: A systematic review and meta-analysis. PLoS One. 2020 Jul 13;15(7):e0236025. doi: 10.1371/journal.pone.0236025. PMID: 32658929; PMCID: PMC7357764.
menstrual cycles. Am J Clin Nutr. 1995 Jan;61(1):39–43.
Kriengsinyos W, Wykes LJ, Goonewardene LA, et al. Phase of menstrual cycle affects lysine requirement in healthy women. Am J Physiol Endocrinol Metab. 2004 Sep;287(3):E489–96.
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