Why Some Women Shouldn’t Fast

Despite the many benefits of intermittent fasting, it is important to keep in mind that it is not always appropriate for all women at all times. Following is a list of conditions where intermittent fasting should not be practiced by women or practiced only under a doctor’s supervision.

Women Who Are Pregnant or Breastfeeding

Studies have reported that fasting during the second trimester causes a 35% higher risk of preterm or premature birth.[1] Additionally, keep in mind that the body’s metabolism and nutritional needs change postpartum to meet the demands of breastfeeding. Fasting for longer hours or restricting calorie intake can significantly impact the production and quality of breast milk.[2]

Women Who Are Trying to Conceive

Undereating caused by fasting can also negatively influence hormone production in females and cause fertility issues.[3,4] Therefore, avoid intermittent fasting if you’re trying to get pregnant.

Women Who Have Pre-Existing Medical Conditions

If you have concerns about any medical conditions, please talk to your doctor before starting your fasting plan. If you are taking any type of medication (especially for diabetes), you should first consult with a physician as fasting may require a change in medicine dosages.[5]

Women Who Have Eating Disorder

Women suffering from eating disorders like anorexia nervosa or binge eating disorders (BED) may experience negative symptoms after fasting.[6]

Women Who Have Excessive Stress or Anxiety Disorders:

Women who have anxiety issues or cortisol issues should not practice intermittent fasting as it can act as a stressor to the body.[4]

Women Who Are Underweight or Malnourished

Fasting involves limiting eating time, which can make it difficult for  underweight or malnutritioned women to take in all the nutrients they need.[5]

Women Who Are Under 18 Years Old (So Not For Teen Girls)

Studies have revealed a variety of fasting challenges in kids of different ages. Small kids without any history of metabolic and endocrine diseases are more prone to hypoglycemia while fasting, even with short  durations. In addition, cardiovascular instability, irritability, mood swings, metabolic dysfunctions, hunger, and thirst are reported as some effects of fasting in kids.[7] However, there is no authoritative research done for teen girls. As a result, it is important to consult a doctor before kids/teens under 18 start fasting.

Women Who Are Professional Athletes

Athletes or people who are training intensely 4-7 days per week have different  energy needs  compared to average people. They should not fast or should fast with great caution. Endurance sports require quick energy from food and partial or total fasting may be challenging or unhealthy for athletes.[8]

Caution to Women Who Have Irregular Menstrual Cycles

Research has shown time and again that irregular periods caused by PCOS show improvement with IF (16:8).[9] However, in females with otherwise regular menstrual cycles, a significant change in daily eating patterns may alter hormonal secretion, leading to irregularities in menstrual cycle.[10]


For this reason, our FastingQueens app includes a period tracker to monitor your menstrual cycle during fasting. To help your body ease into the new eating pattern without disrupting your periods, please check out another article A Complete Guide to Healthy Fasting Without Affecting Your Menstrual Cycle.

  1. Tith, R. M., Bilodeau-Bertrand, M., Lee, G. E., Healy-Profitós, J., & Auger, N. (2019). Fasting during Ramadan Increases Risk of Very Preterm Birth among Arabic-Speaking Women. The Journal of nutrition. Link
  2. Ertem, I. O., Kaynak, G., Kaynak, C., Ulukol, B., & Gulnar, S. B. (2001). Attitudes and practices of breastfeeding mothers regarding fasting in Ramadan. Child: care, health and development. Link
  3. Sushil Kumar, Gurcharan Kaur. (2013). Intermittent fasting dietary restriction regimen negatively influences reproduction in young rats: a study of hypothalamo-hypophysial-gonadal axis. PLoS One.Link
  4. Kim, B. H., Joo, Y., Kim, M. S., Choe, H. K., Tong, Q., & Kwon, O. (2021). Effects of Intermittent Fasting on the Circulating Levels and Circadian Rhythms of Hormones. Endocrinology and metabolism. Link
  5. Grajower, M. M., & Horne, B. D. (2019). Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus. Nutrients. Link
  6. Stice, E., Davis, K., Miller, N. P., & Marti, C. N. (2008). Fasting increases risk for onset of binge eating and bulimic pathology: a 5-year prospective study. Journal of abnormal psychology. Link
  7. Kalra, S., Al Deeb, A., & Sahay, R. (2019). Ramadan fasting in children. The Journal of the Pakistan Medical Association. Link
  8. Valeria Laza. (2020) Intermittent fasting in athletes: PROs and CONs. Health, Sports & Rehabilitation Medicine. Link
  9. Li, C., Xing, C., Zhang, J., Zhao, H., Shi, W., & He, B. (2021). Eight-hour time-restricted feeding improves endocrine and metabolic profiles in women with anovulatory polycystic ovary syndrome. Journal of translational medicine. Link
  10. 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