Women and Fasting
No breakfast? Only 2 meals per day? Dinner at 5? Everywhere you turn people are talking about fasting and its benefits. And it is true, fasting can be an important and easily accessible tool for prevention of disease, longevity, and supporting general good health. But it is crucial to understand fasting impacts women and men differently and may not work for everyone.
So, let’s dive in!
Words to Know
Fasting means to go without food (and sometimes water) for a period of time.
Intermittent Fasting refers to any plan of alternating periods of eating and not eating. When you are sleeping you are fasting. Popular forms of fasting include every other day fasting or the 5:2 diet. With every other day fasting you eat one day and not the next and repeat this cycle. On the 5:2 diet you eat normally (keep it healthy) for 5 days and on 2 non-consecutive days you consume only 500-600 calories.
From what I have read, most experts would agree everyone should aim for a 12 hour fast overnight. This is from the time you take your last bite of food until you take your first bite the next morning. Purists insist you can only have water during your fast. Others say herbal tea (I am in this camp) is OK. Still others I trust say you may have black coffee plain or with grass-fed butter or ghee and some MCT oil without interrupting the fasting period (I have tried this and like it).
Time Restricted Feeding is a form of Intermittent Fasting. In this form of fasting, you consume all your calories within a specific time frame. The most common plan for women is a 14-hour fast (16 for men) and a 10-hour (8-hour for men) feeding/eating window. For example, you would eat breakfast at 9 am and finish dinner by 7 pm for a 10-hour feeding window.
Ketosis is when your body shifts into a fat burning state rather than using carbohydrates (stored as glycogen) as the primary source of fuel. Fasting can help your body get into ketosis.
Benefits of Fasting
”The theory behind Intermittent Fasting (IF) and Time Restricted Feeding (TRF) practices is that there are certain aspects of repair and rejuvenation that the body needs to undergo that it can do more effectively in the fasted state.” Both IF and TRF have been shown to reduce inflammation and are considered tools for extending longevity. Fasting can also benefit your sleep cycle, help reset or maintain a normal circadian rhythm (the bodies regulation of various processes that happen during daylight, active hours v. dark, resting hours), support digestion, and help with disease prevention.
Longer fasts, over 16 hours and closer to 24 hours trigger autophagy. Autophagy is an important biological process in which the body cleans up old and damaged cells or ones which could potentially be cancerous. It is like a deep cleaning on the inside! One research study found “that prolonging the length of the nightly fasting interval (13 hours or more) could be a simple and feasible strategy to reduce breast cancer recurrence.”
Fasting is considered a hormetic stress. The kind of little stress, like a cold plunge or sauna, which can make you stronger and more robust. However, if you have a significant amount of other stress in your life, it might not be a good time to experiment with fasting. It could literally be too much for your body.
And like everything with nutrition and diet, everyone’s experience with fasting will be different and it may not work for some people. You also do not have to take an all or nothing approach. To get the benefits of fasting, you do not have to commit to fasting every day of the week. You could, for example, try doing it for 3 days per week. Lastly, if you are pregnant, nursing, or have significant underlying health conditions fasting may not be right for you either. Regardless, it is always good to check with your doctor first.
Fasting Considerations for Women
There is only a limited amount of research on the impact of fasting on women. This is due to the fact most research on fasting has been done on men and research animals. What is known is women’s bodies and hormones are more sensitive than a man’s to fasting. This is especially true before you hit menopause and pre-menopausal women should be more careful with fasting. Prior to menopause your hormones are still focused on fertility and are sensitive to changes in diet and calorie restriction. If you are in this category, you may want to try and stick with a 12 hour, overnight fast rather than longer fasts. Fasting for post-menopausal women may be easier once the hormonal changes of perimenopause have passed.
An excellent resource on fasting for women (and all its complexities) is this approachable article from Kion. The author nicely summarizes a complex topic where there are still many unknowns. It contains specific recommendations on ways to approach fasting, provides a list of the signs fasting might not be working for your body, and discusses fasting for women with specific health concerns.
Another source for information is Dave Asprey’s (the Bullet Proof coffee guy) book, Fast This Way. He devotes an entire chapter to fasting for women. He explains why due to women’s biological makeup fasting affects us differently and how to approach fasting if you are interested. Reading his book confirmed what I have experienced firsthand and gave me more confidence as I experimented with different approaches to fasting.
The Fasting Mimicking Diet
If you are ready to take your fasting up a level, there is the Fasting Mimicking Diet (FMD). This approach was researched and developed by Dr. Walter Longo, M.D., the Director of the Longevity Institute at the University of Southern California, and a recognized leader in the science of fasting. The Fasting Mimicking Diet is a 5-day, low carbohydrate, and low protein diet. The diet claims to promote cellular renewal, support metabolic health, enhance clarity and performance, and kickstart fat focused weight loss.
I became interested in the FMD because of the purported longevity and anti-cancer benefits of extended fasts. However, I could not imagine doing a 3 or 5-day water fast so I looked for alternatives. Dr. Longo has created a FMD in a box called ProLon, which makes it super easy to implement. I have also used this do-it-yourself version I found online. I do a FMD 2-3 time per year. Anecdotally, I find day 3 the hardest but love how I feel at the end, light and full of energy. Be sure to check with your doctor before taking on any sort of extended fast.
My Current Approach to Fasting
I consider fasting one of my foundational health practices. And, if I do not fast too aggressively it works for me right now. I fast 12 -13 hours each day (overnight). And 2 – 3 times per year I do a 5-day Fasting Mimicking Diet. I have found I can do a 30-minute swim or resistance training in a fasted state, but I must eat before a bike ride or anything similarly strenuous.
It took trial and error and listening to my body to find the right approach to fasting for me. And it took time to build up to my current schedule. I have experimented with 14 and 16 hour fasts and found I did not feel “right.” Plus, the longer fasting interval negatively impacted the length of my cycle (back when it was more predictable).
Parting Thought
“Be kind to yourself” should be the motto for women in midlife. If you are intrigued by fasting, start slowly and remember everyone is different and how you respond to fasting will be unique to you.
See you next week…
