Wondering if fasting is healthy, or seeking insights as it pertains women’s health? This guide can help you get a greater sense of the benefits of fasting and how to make it work for you.
Although fasting is far from a new practice, perhaps it’s new to you. Ahead, you’ll learn about the origins of fasting, popular types of fasts, and tips to practice this dietary pattern in a sustainable way that supports your well-being. Throughout, you’ll also find surprising intel on intermittent fasting for women and other game-changing FYIs you probably weren’t privy to… until now.
The History and Evolution of Fasting
Generally speaking, the practice of fasting has its roots in evolutionary necessity and religious practices. “People all over the world have practiced fasting for most of human history,” explains Mindy Pelz, DC, a holistic health practitioner, fasting expert, and author of Fast Like a Girl. “Back when we were hunter-gatherers, fasting was less of a choice. We would go for hours (sometimes days) without eating, punctuated by huge feasts when someone hunted an animal or found an abundance of fruits, nuts, and so on.”
The religious ritual of fasting is seen across different religions and sects to this day, with Ramadan and Yom Kippur fasts as popular examples. “Buddhist monks also often practice fasting, sometimes for days at a time, as a way to meditate and cultivate inner stillness,” Dr. Pelz adds. In fact, the women’s fasting expert explains that research on religious fasting largely paved the way for the health perks associated with fasting as we recognize them today. “A lot of the early fasting research came from scientists studying people during Ramadan,” she shares. “They noticed that those who fasted experienced all kinds of benefits, which led to more targeted research in a lab setting.”
Studies on patients with epilepsy also set the groundwork for modern-day fasting fanfare. “About a hundred years ago, researchers discovered that intermittent fasting helped stop seizures, and that the people who fasted were healthier in all kinds of other ways,” Dr. Pelz continues. “The field grew from there. Today, fasting is a major field of research for everything from weight loss to longevity.”
Is Fasting Healthy?
Simply put, fasting can be healthy so long as you practice it in a sustainable way that works for your body’s needs. As we’ll soon see, there are different types of fasts to choose from—as well as certain guidelines that can work for (or even against) women and other demographics.
Dr. Pelz provides a general overview of potential benefits of fasting, which include:
Different Fasting Methods
This overview will help you get a sense of popular fasting methods—including if experts give them the green light or a hard pass.
Intermittent Fasting
The 16/8 fasting method—in which you fast for 16 hours and have an eating window of 8 hours—is arguably the most popular type of intermittent fasting (IF), aka time-restricted eating (TRE). “This method is not actually meant to include calorie restriction,” explains Brigitte Zeitlin, MPH, RD, CDN, founder of BZ Nutrition. Instead, it restricts the time frame in which you eat.
According to Zeitlin, this style of fasting can yield a range of health benefits including:
- Lowering risk factors for heart disease
- Protecting memory and cognitive function
- Improved metabolic health (via blood sugar balance, lowering cholesterol, and maintaining a healthy weight)
- A longer, healthier life
While 16/8 is popular, Dr. Pelz says that some people may eventually enjoy longer fasts like 20/4 and one meal a day (OMAD) fasting. Both experts approve of these intermittent fasting protocols that cut time, rather than drastically cut calories. “It’s amazing how much you can upgrade your body and brain, all from not eating for most of the day,” Dr. Pelz shares. Meanwhile, Zeitlin prizes it since it can be a sustainable lifestyle practice to reap the aforementioned rewards in a healthy manner over time.
Longer Fasts and Significant Calorie Restriction
Zeitlin then discusses fasts in which you severely restrict calories. These types of fasts include:
- Fasts in which you don’t eat for 24 hours or longer
- 5/2 fasting, in which you stick to your usual diet for five days and don’t eat (or limit food intake to 500 to 800 calories) for two days a week
- Alternate-day fasting (ADF), in which you follow the same dietary restrictions as 5/2 but enact “feast then famine” every other day
Research illustrates the potential benefits of the 5/2 diet (including adherence and weight loss) and of restricting calorie intake for one to three days a week. According to Dr. Pelz, variations of these more intensive, longer fasts may also be beneficial for specific goals (ranging from gut repair to boosting dopamine) and certain people.
That said, Zeitlin doesn’t suggest these methods—especially for women. These fasting protocols “can interfere with hormone production, which is crucial for women thinking about fertility and women at the peri/postmenopausal stage,” she explains. “Additionally, [they] can be harmful for our bone health and be a risk factor for osteoporosis, which women are already at an increased risk for.”
9 Healthy Fasting Tips
Interested in trying fasting out for yourself? Be sure to heed the following tips and FYIs.
1. Get Clear on Your Priorities
To start, Zeitlin advises honing in on your goal or intention for fasting. Is it weight loss, improved metabolic health, promoting longevity, or something else? From there, she wants you to consider if you can adopt it as a healthy and sustainable lifestyle practice. “Otherwise, you may be back on a diet-mentality rollercoaster,” she cautions.
2. Get Approval from Your Healthcare Team
As is the case with making any major dietary change, it’s always wise to consult a trusted healthcare professional. This is especially pertinent if you have a medical condition, including a history with disordered eating.
3. Start Modestly
If you’re kicking off an intermittent fasting protocol, it’s okay—and advised—to start with a modest time-restriction window as your body adjusts. “It all depends on what works for you, though I would say that you want to go at least 14 hours without food, and ideally 16+ hours. That’s when the benefits of fasting start to kick in,” Dr. Pelz shares.
4. Limit Bites at Night
Your fasting period should naturally overlap with your sleeping period (that is, unless you’re prone to sleepwalking straight to the kitchen). Eating an earlier dinner and kicking any late-night snacking habits can also help you lengthen your fasting window with relative ease.
5. Nourish Yourself During Eating Windows
In order to benefit from fasting, you’ll still need to feast on balanced, nutritious meals and snacks during your non-fasting windows. “Make sure that you are eating a variety of fruits and veggies, and include a protein and healthy fats at each meal/snack,” Zeitlin advises. “This will keep your energy up, improve quality of sleep, and promote a healthy GI system.” All the while, staying on top of your nutrition game will maximize your chances of achieving the fasting goals you set at the fore.
P.S. Zeitlin adds that nourishing yourself also entails enjoying your favorite foods—including salty and sweet fare—in moderation.
6. Drink Up
“Water, tea, and black coffee are all great during fasting,” Dr. Pelz shares. So long as the drink doesn’t have calories, it won’t break your fasting window. Of course, staying hydrated is crucial whether or not you’re fasting. Zeitlin suggests aiming to sip on half of your weight in ounces of water throughout the day.
7. Enjoy a High-Fat Snack
There’s one fact about healthy fasting that doesn’t seem to get enough airtime, but absolutely should. Drum roll, please: It’s totally fine to have a snack while fasting. (Yes, really.) “A study from 2021 found that people who had a snack after 12 hours of fasting, then continued fasting afterward, enjoyed all the same benefits as people who fasted without a snack,” Dr. Pelz shares.
There’s just one caveat: The snack has to be rich in fat. (Carbs and protein, on the other hand, will kick you out of a fasted state.) To extend your fast and optimize health benefits, Dr. Pelz suggests opting for one of the following high-fat snacks:
- Half an avocado with salt
- A few tablespoons of nut butter
- Coffee with butter and MCT oil
8. Align Your Fast with Your Menstrual Cycle
“Contrary to popular belief, fasting is great for women,” Dr. Pelz emphasizes. “I work with hundreds of women who see amazing benefits from intermittent fasting.” However, there’s one IF tip that all women who menstruate should heed: timing your fasts with your monthly cycle to support hormonal balance.
“You may want to avoid fasting in your luteal phase, which is seven to 10 days before your period,” she advises. “Take it easy on your body and don’t do anything too stressful during this time. It’s hard enough without trying to fast.”
9. Enlist the Help of a Dietitian
Enacting major dietary changes can be challenging, to say the least. If you’re overwhelmed, confused, or prefer personalized guidance, working with a dietitian can set you up for lasting success. Zeitlin says that RDs can help you customize your plan to align with your goals, as well as offer tips so you can seamlessly integrate fasting into your lifestyle. (This could include how to navigate social or family dining, work and travel scenarios, and the like.) Professional, hyper-customized guidance can ensure that fasting “will work for you for the long term and have you feeling great,” she concludes.