Intermittent Fasting for Women

There are actually several different types of intermittent fasts: time restricted eating (TRE), alternate day fasting (ADF), one meal a day (OMAD), among a few others. The most well-known and widely practiced one is time restricted eating. This refers to eating within a specific window of time, allowing your body a specific number of hours to rest and not be concerned with digesting food. The most common TRE fast is the 16:8 fast. This means you fast for 16 hours and eat within an 8 hour window. 

The benefits of this type of intermittent fasting are undeniable (1): weight loss, easing symptoms of PCOS, reduce inflammation, reduce blood pressure, improve self-esteem, reduce anxiety and depression, improve metabolic flexibility, reverse insulin resistance, the list goes on.  It even has been linked to suppressing cancer! Fasting has been a great tool that I have used postpartum to improve my overall health and many in my family have used it with great success in losing weight, improving metabolic flexibility, improving A1C levels as well as relieving stress from the liver.

The issue with fasting comes when we start to look at it long-term. While fasting can be a powerful tool to heal the body and teach it how to properly burn fat, it can also be a pretty stressful experience for the body. Fasting, especially the longer you go, creates a sort of “starvation” mode in the body. This means stress, stress means cortisol (2). Fasting long term will also begin to affect estrogen and progesterone, specifically dropping them a significant amount. The drop in estrogen and progesterone in combination with the increase in cortisol can be the perfect combination to create a hormonal disaster. This is especially the case for mothers of young children, who tend to have higher levels of cortisol already. 

Plenty of women are able to intermittent fast while pregnant and breastfeeding as well, the main concern when pregnant and breastfeeding is not being able to eat sufficient calories within a shorter eating window.  While pregnant, I wouldn’t extend a fast longer than 12 hours just to ensure sufficient calories. While breastfeeding I was able to fast longer, sometimes extending my fast to 16 hours. They key while breastfeeding is to ensure sufficient water intake because breastmilk is mostly water. You can keep up your milk supply by ensuring you are well hydrated. 

It is because of all the possible negative effects to the sensitive female hormones I personally do not fast longer than 12-14 hours on a regular basis. I will occasionally fast for 16-20 hours for a couple weeks at a time but then give myself a break from it and go back to a 12 hour fast. 

If you want a deep dive into everything to do with fasting for women including ideal foods, I highly recommend this book by Dr. Mindy Pelz, Fast Like a Girl. She has done some amazing research into this topic and this is a great read if you really want to optimize your fasting experience.

Sources:

1. Nair PM, Khawale PG. Role of therapeutic fasting in women's health: An overview. J Midlife Health. 2016 Apr-Jun;7(2):61-4. doi: 10.4103/0976-7800.185325. PMID: 27499591; PMCID: PMC4960941.

2. https://www.eatingwell.com/article/7874733/intermittent-fasting-for-women/