Fasting is a hot topic these days, but is it really worth the hype?
Fasting is actually not a new fad. It has been around since the beginning of times. Many different religious and spiritual traditions as well as ancient healing practices such as Ayurveda incorporate fasting as a healing method.
The wisdom in fasting is long withstanding. However, as I was exploring the various fasting techniques and how to implement them into my lifestyle, some key questions came to mind:
Should women be fasting differently than men and if so, what does that look like in practice?
Do women need to adapt their fasting to where they are at in their reproductive phase?
What are the different approaches to fasting?
What are some key hacks to support fasting?
Read on to find out the answers to these questions, and much more!
If you are pressed for time, click here for the key takeaways by topic and check out the "bottom line" for each section:
What is fasting?
Many different diets and ways of eating focus on what you eat, but fasting is about when you eat. It is a pattern of eating that alternates eating times with periods of not eating.
According to Cynthia Thurlow, Intermittent Fasting and Nutrition Expert, quite simply put, it is the “absence of food during a prescribed time period.”
But why would we want to deprive ourselves of food? Well, there are actually a number of benefits to fasting.
The many health benefits of fasting
More and more evidence is building to document the benefits of fasting. While the long-term effects of fasting have not been fully established and the bulk of research has been done on obese people, men and lab animals, the research continues to evolve, with more studies demonstrating the potential benefits of fasting approaches to support health and healing.
When done correctly, fasting can help with a number of health outcomes. Here I focus on what I consider to be some of the most important ones.
1) Weight loss
When in a fasted state, your body is not getting its energy from glucose (its main energy source) so it has to look for alternative energy sources. As a result, your body starts to break down stored fat into ketones (made in the liver from the breakdown of fats). Ketones now become the fuel for your cells and your body is able to draw from its fat storage.
Reviews (Welton et al., 2020; Cioffi et al., 2018; Bonnet et al., 2020) have shown that fasting can indeed help with weight loss and may reduce obesity.
2) Improving insulin sensitivity and reducing the risk of diabetes
Insulin is a hormone that helps deliver glucose to your cells and thereby regulates the amount of sugar circulating in your body. When your bloodstream is overwhelmed by sugar, your cells stop responding to insulin, putting strain on your pancreas to produce even more insulin. This is called "insulin resistance".
Eventually, your pancreas will burn out if you continue to consume too many carbs and sugar, leading to diabetes and a host of other co-morbidities.
Fasting can enhance the ability of your body to reduce fasting glucose levels and decrease insulin resistance (Cho et al., 2019; Mattson et al., 2017).
3) Decreasing inflammation in the body
Chronic inflammation is the root cause of most illnesses. Fasting can lower the production of inflammatory markers such a C-reactive protein (Wang et al., 2020). Certain compounds produced by the body when fasting can modify inflammatory pathways (Youm et al., 2015; Intermountain Healthcare Heart Institute, 2021).
4) Supporting the process of autophagy
Autophagy is basically a cellular spring cleaning. The body breaks down old, damaged cells and recycles them to create new healthy cells. Fasting can help support the process of autophagy (Mattson et al 2017; Bagherniya et al., 2018). This is a promising area of research.
5) Upping energy levels by strengthening mitochondrial health Mitochondria are the energy powerhouses in all our cells. We need them and they sustain us. Fasting has been shown (Lettieri-Barbato et al., 2018) to support the process of mitophagy — a process by which old and damaged mitochondria are broken down and replaced with new and healthy mitochondria, thereby supporting cellular energy.
Bottom line: There are many health benefits to fasting including weight loss, improving insulin sensitivity, supporting cell renewal, upping energy levels and decreasing inflammation in the body.
Different approaches make it doable to fast
Fasting can seem daunting. While many people may associate fasting with restricted eating for very long periods of time, there are actually different timing approaches that are very doable.
In fact, you may already be fasting without even realizing that you are doing so!
The most basic kind of fast is the one that takes place between dinner and breakfast. Fasting during this time falls in line with our natural circadian rhythms. When the sun is up we eat, when the sun is down we don’t eat. A 12 hour fasting period is the ideal minimum, giving your digestion and gut a break.
You can gradually increase this fasting period to last longer. There is a lot of flexibility here in terms of time restricted eating. You can determine how big or small your eating window is: eating within a 12 hour period (12/12); or a 4 hour period (20/4).
Some practitioners recommend a 16:8 ratio (also known as the Leangains Diet) as a good option.
Ultimately though, it’s really up to you — but make sure you are getting guidance from a practitioner to ensure that the option you are choosing is the best possible for your body’s needs.
Some other popular fasts include:
* OMAD (One meal a day), which can also be referred to as a 23:1, means you are fasting for 23 hours and eating within 1 hour.
* The 5:2 approach which allows you to eat as you normally would five days a week. The other two non-consecutive days are considered your fasting days, where you consume 25% of your caloric needs (keeping your calories to no more than 600).
* 24 hour fasts: You restrict all food for 24 hours, once or twice a week.
* 3-5 (or longer) day water fasts.
For these longer fasts, make sure that you know what you are getting yourself into and get guidance!
Bottom line: There are many different ways to fast such as intermittent fasting, OMAD, 5:2 and 24+ hour fasts which makes it easy to play around with in order to find an approach that resonates for you.
Tips on how to be successful at fasting
Begin with a fasting window of 12-13 hours, a couple of times a week and see how you feel. If you are feeling well, then increase by an hour at a time and see where you feel best. During this fasting time frame, you can drink plain coffee or tea.
Give it 30 days to see if fasting is right for you. It may take up to 6-8 weeks for you to experience any benefits or change.
Mix it up. Once you’ve mastered basic fasting, play with the other fasting methods, if that resonates for you. According to Cynthia Thurlow, most women will not do well if they fast in the same exact way every single day (see her Ted talk).
Make a schedule for yourself and a plan for when you will be eating vs fasting and what you will be eating.
Make sure you feel satiated during your fasting period. This is best ensured by eating nutrient dense foods. This translates to eating healthy fats, high-quality proteins, unprocessed foods and non-starchy veggies. You’re not likely to achieve your health goals if your feeding times are packed with things like junk food.
Keep your cortisol levels under control. Cortisol is secreted when we are stressed. If cortisol is high, it will make managing insulin more difficult and may compromise your fasting efforts to bring insulin levels down.
Those who overexercise also tend to have too much cortisol coursing through their bodies and therefore have a hard time regulating insulin. So be mindful of your work out routine and don’t overdo it.
Bottom line: Set yourself up for a successful fast by implementing a few ground rules around fasting such as making sure you are satiated during your fasting period, mixing up different fasting methods and keeping your cortisol levels down.
Why fasting for women looks different than for men
Basically, fasting looks different for women because we have more hormone flux than men.
According to Mindy Pelz, Holistic Health and Fasting Expert, fasting has been shown to be safe for women, but it’s important that women sync up fasting with their cycle or where they are at in their reproductive years.
Her recommendations are as follows:
For women under 40, the ideal time to fast is around days 1-12. When women experience an estrogen surge around days 12-14, they should avoid longer fasts.
Women will also want to avoid fasting during the second half of their monthly cycle, especially days 21-28 when the body needs to make progesterone. It is a time to consider stepping out of ketosis and increasing carb intake.
Perimenopausal women between the ages of 40-55 will also want to be very mindful of varying their fasting to support progesterone, as this hormone begins to decline quite noticeably during this time.
Another thing to consider is that stress will impact the production of progesterone. Women will need to be mindful to not be stressed when doing longer days of fasting.
At this time in life the adrenals take over the job of making hormones so women need to think about strengthening their adrenals by leaning into hormone building foods such as beans, rice, squashes, citrus and tropical fruits.
Women over 55 will also want to mind their progesterone, stepping out of a fasted state at least one day a week, adding hormone building days and incorporating different eating and fasting styles.
Make sure to check out Mindy Pelz’s you tube channel and her website, which have a wealth of information on the topic.
Cynthia Thurlow recommends a somewhat similar regimen for her clients. Because there is more estrogen circulating during the follicular phase, she recommends eating lots of cruciferous vegetables and flax seeds as well as getting liver support (beets, dandelion, bitter greens) to be able to package up the extra estrogen circulating in the body.
During the luteal phase, during which time women lose estrogen, women are more insulin resistant. She recommends eating whole food carbs (like sweet potato, squash, root veggies) and adding a fat such as butter to feel satiated.
She advises women to be cautious with fasts that last more than 24 hours, especially for women who are lean. It can put these women’s bodies under quite a bit of stress, thereby increasing cortisol levels.
Bottom line: Women should fast differently than men by paying attention to their cycle or where they are at in their reproductive phase.
Who should avoid fasting
Fasting isn’t for everyone. People who have a difficult time controlling diabetes; children and adolescents; the elderly over 70; pregnant and breastfeeding women; those with chronic heart issues or renal issues; and women who have a disordered relationship with food should avoid fasting.
Be sure to talk about fasting with your practitioner to decide if it is right for you.
Additional resources
How to Use Intermittent Fasting to Lose Weight, Live Longer, and Feel Better with Dr. Jason Fung (podcast)
Intermittent Fasting: Surprising Update (article):
Dave Asprey’s IF Fasting Guide:
How to Use Intermittent Fasting to Lose Weight, Live Longer, and Feel Better with Dr. Jason Fung (podcast)
Bottom line: It may take you some time to figure out which fasting approach works best for you. Or you may even decide fasting is not for you. And that’s okay too! What’s important is that you do YOU.
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