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3 Tips For Safely Trying Intermittent Fasting, Doctor-Approved

Jason Wachob
mbg Founder & Co-CEO
By Jason Wachob
mbg Founder & Co-CEO
Jason Wachob is the Founder and Co-CEO of mindbodygreen and the author of Wellth.
Image by mbg Creative
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November 12, 2019

If there was a reigning expert in intermittent fasting  for women, Amy Shah, M.D., could very well hold the title. As an mbg class instructor with training from CornellColumbia, and Harvard Universities, she was (unsurprisingly) named one of mindbodygreen's Top 100 Women in Wellness to Watch in 2015. Despite seeing numerous clients as a double board-certified physician, Shah believes we have the power to take control of our own health. "Health and wellness happen outside the doctor's office: Your best physician is good nutrition and your own mind," she's previously told mbg.

On this episode of the mindbodygreen podcast, it's probably not a shock that Shah and I had much to discuss regarding intermittent fasting. In this episode, she explains an ideal fasting day in the busy working world, what to do if you're struggling with your fast, and what a fasting schedule looks like for menstruating women. 

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She also mentions how we can navigate the very personalized (and sometimes ambiguous) world of intermittent fasting. While it's always best to discuss your own eating habits with your doctor, Shah gives great direction for people who might not know where to start when it comes to fasting. 

Here are three tips from Shah on how to know which type of intermittent fasting is best for you. Whether you're a fasting pro or you're just starting your IF journey, you'll want to check out Shah's expert-level advice:


Check in with your hormones. 

We already know that fasting can work differently for women on a chemical level. "It's not that you cannot do fasting as a woman," Shah notes. "It's that we are hard-wired to be more sensitive to external stressors." 

That said, in order to make sure you're fasting safely and effectively, you might want to periodically check in with your hormones and make sure there aren't any glaring issues. Shah offers some factors (four, to be exact) you can mark off your mental checklist as you fast, just to make sure you're on the right track. 

"Is your energy good? Are your periods regular, or are you getting missed or irregular periods? Because that's a sign of ovulatory dysfunction. How are your hunger and cravings?" And finally, "Check on your sleep. Is your sleep disturbed?" 

These checks are so important to keep in mind, no matter your gender (apart from checking in on your menstrual cycles), because each can uncover important signs about your hormones. If you are experiencing any of these symptoms, Shah recommends you talk with your doctor, as you might need to ease up on the intermittent fasting or change your plan entirely.


Try cycling in and out. 

Especially if you're intermittent fasting for weight loss, cycling the number of hours you fast is crucial, according to Shah. 

"You have to remember that our metabolism adjusts," she says. "So if you fast every day for 16 hours and take in low calories on those days, your metabolism will turn the thermostat down." So, switching up your fast can keep your metabolism on its toes (plus, it might make intermittent fasting a much easier feat to accomplish). 

"I think cycling in and out is really, really a nice way to give your body a break and also push your body a little bit," she adds. It may seem obvious, but it seems as if listening to your body as you fast is the way to go; if you feel that your body needs a break, take it! 

Shah personally switches up her fasts, as this system feels best for her body. "I'll do three longer fasts a week, and I'll do three shorter fasts, and then I'll do one day off," she says. 

How you plan those shorter and longer fasts is completely up to you—and you can even switch it up from week to week. According to Shah, the key is to get creative. 

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Remember: Even a little can go a long way.

This tip is specifically for those who are struggling with intermittent fasting. If you're hungry or miserable, don't force it! Shah says that even 12 or 13 hours of fasting can have significant effects on our health—there's no reason to jump right into a 16- or 18-hour fast from the get-go. 

"Research has looked at just 13 hours of fasting in a group of women who had breast cancer history, and they found a 34% reduction in breast cancer recurrence. So you can get profound benefits, even with short fasting windows," she says. 

So, if you're new to intermittent fasting (or maybe you're just having a hard time with it), you may want to take this "less is more" approach. As long as there's some sort of time-restricted eating model, you can reap the many benefits of intermittent fasting, says Shah. 

"I think a lot of the lay media really pushes people to do 16, and 18, and plus on a daily basis. But I think that you can start to see benefits even earlier, especially when you're doing this time-restricted eating model." 

You can even eat a spoonful of nut butter or avocado if you're feeling especially peckish in the morning—Shah says that you can eat up to 40 non-sugar, non-protein calories if you're having trouble with your fast, and you won't steer from your intermittent fasting goal. 

Before you embark on your IF journey, it's important to keep these guidelines in mind. Just the term "intermittent fasting" alone involves tons of different information, definitions, and eating plans, and—as always—it's best to navigate your way through health trends as educated and informed consumers. Although Shah has many more tips and tricks under her belt, these three pieces of advice will help you get started on a fasting plan that's safe, effective, and personalized to you.

Enjoy this episode sponsored by Yogi Tea! And don't forget to subscribe to our podcast on iTunesGoogle Play, or Stitcher, and sign up for our podcast newsletter!
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Jason Wachob
Jason Wachob
mbg Founder & Co-CEO

Jason Wachob is the Founder and Co-CEO of mindbodygreen and the author of Wellth. He has been featured in the New York Times, Entrepreneur, Fast Company, and Vogue, and has a B.A. in history from Columbia University, where he played varsity basketball for four years.