Why You Should Avoid Excessive Fasting Before Your Period

A woman’s body is highly influenced by the sex-steroid hormones. Hormonal levels fluctuate systematically to maintain the energy homoeostasis during the menstrual cycle. [1] These ever-changing hormones in the female body makes fasting far more complicated for women than for men. Thus, when you’re considering intermittent fasting, keep in mind that energy restriction and limited food consumption may alter the metabolic and neuroendocrine responses contributing to menstrual irregularities. [4]


The Science Behind Your Menstrual Cycle

The menstrual cycle’s periodic hormonal changes have an important biochemical impact on the female body, with multiple physical and emotional repercussions. [2] The second half of the menstrual cycle is characterised by a rise in estrogen levels with a progesterone peak followed by the premenstrual phase with a fall in estrogen and progesterone levels. [5]

In women, reproductive and menstrual health is chiefly controlled by a series of external and internal inputs to the brain, including nutritional and caloric intake, energy expenditure, and stress levels. These inputs act together and affect the hypothalamic-pituitary-gonadal (HPG) axis in the higher centres of the brain. This in turn influences the gonadotropin-releasing hormone (GnRH), which supports the release of estrogen, progesterone, and testoterone from the ovaries throughout the stages of the menstrual cycle. [6]


Effects of Fasting on Menstrual Cycle

Before you begin an intermittent fasting schedule, consider how it may influence your hormonal, reproductive, and menstrual health. As limited research is available regarding the impact of intermittent fasting on menstrual cycle in humans, research on weight management and calorie restriction could help us answer questions about the impact of intermittent fasting on a woman’s health.

Fasting and other forms of calorie restriction acts as a stressor for the body, which in turn sends inputs to brain to modify the release of sex hormones. Extreme caloric restriction, weight reduction, exercise, and nutritional deficiencies can all cause amenorrhea, or irregular or missed periods. [4]


Why You Shouldn’t Overdo Fasting the Week Before Your Periods

A woman’s body is particularly vulnerable to stress in the week leading up to her period, which is part of the luteal phase. During this phase, estrogen levels drop drastically. The production of cortisol (the stress hormone) increases and may cause changes in mood.

Just before your period, you may need to increase energy intake by eating foods high in carbohydrates and fat. [1] As a result, you should avoid fasting throughout the week before your period, or opt for an easy 12 to 14 hour fast. Additionally, if you start craving sweets during the eating window, try healthy options like fruits , yogurt, smoothies, and 70% dark chocolate.


The Bottom Line

Intermittent fasting may be beneficial for many, but it’s not meant for all women at all times. Like any other diet or fitness plan, you should listen to your body and back off if it’s too intense. Before beginning an intermittent fasting program, ask your doctor about any concerns you may have.


  1. Davidsen, L., Vistisen, B. & Astrup, A. (2007). Impact of the menstrual cycle on determinants of energy balance: a putative role in weight loss attempts. International journal of obesity. Link
  2. Farage, M. A., Osborn, T. W., & MacLean, A. B. (2008). Cognitive, sensory, and emotional changes associated with the menstrual cycle: a review. Archives of gynecology and obstetrics. Link
  3. Yavangi, M., Amirzargar, M. A., Amirzargar, N., & Dadashpour, M. (2013). Does Ramadan fasting has any effects on menstrual cycles? Iranian Journal of Reproductive Medicine. Link
  4. Ikhsan, M., Siregar, M.F.G., Muharam, R. (2017). The relationship between Ramadan fasting with menstrual cycle pattern changes in teenagers. Middle East Fertility Society Journal. Link
  5. Draper, C.F., Duisters, K., Weger, B. et al. (2018). Menstrual cycle rhythmicity: metabolic patterns in healthy women. Scientific Reports.  Link
  6. Joseph, D. N., & Whirledge, S. (2017). Stress and the HPA Axis: Balancing Homeostasis and Fertility. International journal of molecular sciences.  Link