Why Intermittent Fasting Is Different For Women

Thanks to the popularity of high fat, low-carb diets like the ketogenic way of eating, intermittent fasting is all the rage. But what does it actually mean?  

In general, intermittent fasting refers to cycling between a period of fasting (or avoiding all food and caloric drinks) and eating as usual throughout a defined schedule. For some people, this means fasting on alternate days. For others, this means dividing the day into a fasting period and an “eating window” (e.g., eating only from noon to 6 p.m.), also known as time-restricted eating.

Research on intermittent fasting shows promise for a number of positive benefits, especially when it comes to the prevention and improvement of diabetes, obesity, cardiovascular diseases, and markers for aging. With rates of diabetes on the rise, research is particularly interested in the big impact fasting appears to make on blood sugar regulation. 

However, some surprising differences between intermittent fasting for men and women have been noticed. Keep scrolling to learn the facts and get tips on intermittent fasting for women.

In studies on intermittent fasting, a common measurement is glucose clearance, or how quickly your body is able to make sugar from your food and get it into your cells to give you energy. Another important measurement is insulin sensitivity, which measures how much attention your body is paying to the hormone insulin, which springs to action once sugar enters your bloodstream and starts knocking on the doors of your cells to “let sugar in!” 

Slow glucose clearance indicates that your cells are taking their time “opening their homes” to sugar, while impaired insulin sensitivity would mean they’re not listening to insulin “knocking on their door.” These two factors can lead to big problems, as we see in conditions like diabetes.

A small study conducted in 2012 suggested that alternate day fasting caused no changes in serum glucose clearance in non-obese men; in fact, the fasting seemed to improve their insulin sensitivity with their next meal. But in non-obese women, glucose clearance declined, signifying that their insulin sensitivity was now worse, thanks to a period of alternate day fasting.

While it’s no secret that men and women are different, they surprisingly may include diverse approaches to regulating blood sugar. Although diet and lifestyle are important considerations, studies suggest that, overall, women may more commonly have issues with glucose clearance. Some experts think this may have to do with our differing body compositions, while others think women may be more prone to insulin issues because of differences in carbohydrate metabolism. 

Studies have also suggested that male and female livers may perform differently when regulating glucose while fasting, and that us women release less glucagon (a hormone released to help raise blood sugar levels when they are low) to fuel us through and after exercise compared to men.

Researchers are still putting the pieces together on exactly how different types of intermittent fasting affect us and what may be the best approach for men vs. women. In the meantime, intermittent fasting, done properly, could still be a great fit for your lifestyle and health goals. (Note: Before beginning any new dietary regimen, it is recommended to check with and gain approval from your doctor first.) If you’re a woman looking at trying intermittent fasting, here are some tips.

As with any big diet or lifestyle change, giving your body adequate time to adjust may be your best bet for success. It’s a good idea to experiment with intermittent fasting during different periods of the day, rather than sticking to one eating window religiously. Ease yourself into it with time-restricted eating two to three days a week during for your first few weeks.

Just as there are different diets and ways of eating, there’s more than one way to practice intermittent fasting. What works like a charm for your best friend might not be the right fit for you, so try out a few different styles and check in with how you feel during each. Also, consider that some research shows that eating your calories earlier in the day may be more beneficial than intermittent fasting in the morning and feasting later.

In a study among women 18 to 30 years old, most participants ate more while they were pre-menstrual. Other studies believe this is because our energy needs legitimately increase during this time and the body needs around 90 to 500 calories more than usual. So when experimenting with intermittent fasting, keep in mind that you may want to change your fasting days or times based on where you are in your cycle.

If you’re prone to losing high amounts of iron during menstruation, it’s also good to prioritize getting enough iron-rich foods (think: spinach, lentils, quinoa) into your diet at this time rather than fasting perfectly. As always, check in with your doctor for their recommendations.

When changes in your diet throw off your body, you’re sure to feel it. Be on the lookout for signs that intermittent fasting may be negatively impacting you and your hormones. Indicators of this could be changes to your menstrual cycle, loss of your period, anxiety, or sudden difficulty with sleep. If you’re used to strenuous exercise, try out lighter exercises while you intermittent fast.

By Dr. Kali Olsen, ND