Expert Insights from Cynthia Thurlow, NP: Fasting, Nutrition, and Women’s Health

Written and medically reviewed by Nicole Grant, RD

As interviewed by Nicole Grant, RDN

Cynthia Thurlow wants you to know that intermittent fasting can change your life. And also: You probably need to eat more protein.  

Cynthia Thurlow, NP, is a world-renowned fasting and nutrition expert. As a clinician, author, and podcaster, she educates and empowers people around the world — especially women — to use intermittent fasting to achieve a healthier, longer life. We recently spoke with her about her best-selling book, Intermittent Fasting Transformation, and explored the benefits of fasting for women, the importance of optimal protein intake, and more. Here is some of the wisdom she had to share.

Q&A with Cynthia Thurlow: The Power of Intermittent Fasting and the Importance of Protein for Healthy Aging

Q: Please tell us your story of how you found intermittent fasting and what propelled you to focus your career on helping so many people achieve health with fasting.

A: I am an adrenaline junkie. I loved working first as a nurse in the emergency department, and later cardiology as a nurse practitioner (NP), where I helped manage patients in the ER, ICU, and trauma units. You name it, I did it.  But after 16 years of being an NP, I started to grow increasingly disillusioned with our current medical model because I felt like all I was doing was putting patients on more and more medication. It got to the point where I just couldn’t write another prescription. And so, in April of 2016, I left clinical medicine to become an entrepreneur, nutritionist, and health coach. 

From there, I went on to do additional training, a lot of it in functional and integrative medicine. It really affirmed for me that I was on the right path. Then, I decided to do a TED Talk. I might be an adrenaline junkie, but I’m also incredibly introverted; I told my husband, “I think if I do a TED Talk, this will be a scary yet safe challenge.” So in the fall of 2018, I accepted my first TEDx Talk. A few months later, I accepted a second TEDx Talk and chose to focus on intermittent fasting for women. Little did I know that the TED Talks would be so successful.

Today I humbly sit here knowing that I did not choose fasting; fasting chose me. The timing of my own professional and health circumstances collided with the power of fasting, and I am so grateful to now be helping people leverage intermittent fasting to build health and happiness in their own lives. 

Q: Your TEDx Talk remains a wonderful resource for women interested in reclaiming health with intermittent fasting. Can you tell us more about the lead-up to that talk?

A: About a month before the TEDx Talk in 2019, I got really sick. I thought I had food poisoning, but eventually the pain was so severe that I had to go to the hospital. It turned out I had a ruptured appendix, plus a slew of complications. My life was literally on the line, and half a dozen different specialists were brought in to figure out a plan for me. 

While I was in the hospital, I couldn’t eat, and I lost close to 15 pounds in just thirteen days. Still, I was anxious to get home to my children, and I really wanted to do the TEDx Talk — I felt like being able to accomplish this would prove I was still OK. Three days before my talk, the doctors removed the drain from my fistula, and I went on to give the TEDx Talk. 

Most people who experience a ruptured appendix with an extended hospital stay have to undergo intensive rehab. I didn’t, and I attribute that to the metabolic health I built with intermittent fasting. The experience was terrible and traumatic at the time, but it led me to learn so many great lessons, both personally and professionally. 

Q: Fasting is a powerful health tool. Based upon your own health and clinical experience, how does intermittent fasting transform or improve health and longevity, especially for women?  

A: People come to fasting for different reasons. I found fasting because I was in the throes of perimenopause, and it seemed clear to me that some of the conventional medicine wasn’t working. Perimenopause is a dynamic time in midlife for women. In my experience, clinicians were quick to say that in your early-to-mid-forties you should expect to put on weight and not feel like your younger, more vital self. There was an attitude of “you’re getting a little older, and this is the way life is going to be now.” That attitude bothered me and prompted me to dig deeper.

I find that for women, fasting helps manage body composition and weight gain throughout various life stages. Considering only about 7% of our population is metabolically healthy right now, there are so many who can benefit from the transformative power of intermittent fasting! I know I personally felt so much better fasting and not eating too frequently. I was not tempted to eat so many snacks, and the weight eventually came off. I had more energy. I slept better. But it’s not exclusively about fasting, either. I often recommend the Zero app to help people track their fasts and build healthy habits. It’s important to approach health from a variety of different angles so you don’t put all your emphasis on one specific thing. 

Q: What other health habits, technologies, or strategies do you recommend people incorporate into their lifestyles to maximize healthspan?

A: In addition to intermittent fasting, I highly recommend people occasionally engage in food tracking. The process is not the most fun, but the learning is so important since so few people really know what they consume throughout the day. And you can’t change what you do not measure. You don’t necessarily have to measure everything out; instead, food logging can be centered around what makes your body feel good. We’ve gotten so disconnected from talking about the connection between food and mood. Identifying what foods you eat that make you feel fantastic afterwards and what foods make you feel sluggish is very important. Food tracking is highly insightful and pairs perfectly with intermittent fasting because your nutrition should be prioritized when you’re limiting the hours of the day in which you eat.

I’m also quite committed to good sleep because the research supports that great sleep has been waning in the last century and is foundational to our health. I’m a bit of a data geek, and I take extra precautions to try to maximize my sleep because I find, for me, it’s a large piece of my overall healthy habit structure. I target getting 90 minutes each of REM and deep sleep. Apple Watch and Oura Ring are also wearables I rely on to help me improve the habits I believe will contribute to maximizing healthspan. The caveat here is that if the devices stress you out, don’t feel compelled to use them. They’re certainly not mandatory to form healthy habits.

Finally, for women specifically, as they approach perimenopause, I think considering hormone replacement therapy, or HRT, can improve quality of life and healthspan. A little over a century ago, women’s life expectancy was between 45 and 50 years, so women likely didn’t live long enough to even experience menopause. Now, longer lifespans mean that HRT might be an important consideration for many women. It is a conversation women should be having, but, ultimately, it’s a personal decision for you and your care team. 

Q: Protein has been a hot topic recently. Can you explain your approach to getting adequate protein while intermittent fasting?

A: First, I want to give credit to Dr. Gabrielle Lyon. For those who don’t know, she’s a huge proponent for sustained muscle health being the key that unlocks longevity and metabolic health. She has helped me update my stance on protein as more data and science have emerged. 

I’m a big proponent of focusing on protein to nutritionally support muscle and bone mass throughout the lifespan. Sarcopenia, the clinical name for muscle loss, is not a question of if, but when; therefore, we want to do as much as possible to circumvent and delay that muscle loss, especially as we surpass age 30. After age 40, we start losing muscle at a more accelerated rate. This is undoubtedly a contributor to metabolic-health decline, as muscle is directly linked with insulin sensitivity. Therefore if you want to support metabolic health, then you need to be focused on supporting strong, healthy muscles. Two of the best ways to do that are to 1) develop regular exercise habits, including resistance exercise at least 2–3 times per week, and 2) ensure you’re eating enough protein to make that exercise count while supporting healthy aging.

I regularly hear people say, “I was told by my trainer that I can only absorb 20–30 grams of protein with a meal.” But when it comes to protein, recent research suggests that it’s more important to meet your protein needs over a 24-hour timeframe, no matter how you do it. The metric that I have many people start working towards is at least 100 grams of protein a day. From there, depending upon body size, we usually target one gram per pound of total, or ideal, body weight. If you weigh 120 pounds, then 120 grams becomes your daily goal. If you get 100–120 grams, that’s a really good day. 

I do find that there is a mental block in some cases, particularly in women. That’s why I really try to help women, and people in general, understand that the RDA is sufficient for avoiding protein deficiency, but most are eating too little protein to support their health and a high quality of life as they age. So if you’re north of 40 years old, you’re already at risk of muscle-mass loss, and the more muscle mass you lose, the more you’re likely to see it replaced by adipose tissue. And then, because fat is an inflammatory tissue, you’ll be more at risk for developing insulin resistance, diabetes, and/or metabolic syndrome. If you exchange lean muscle for fat, you can also suffer from leptin resistance, which causes you to have a hard time feeling full after meals, fueling a nasty cycle that can further damage your metabolic health.

Q: In addition to protecting muscle mass and supporting muscle health, are there other benefits associated with prioritizing dietary protein?

A: I find that for a lot of people I’ve worked with, when they’re hitting those higher levels of protein — so 30, 40, 50, 60 grams of protein in a meal — they can easily maintain their satiety and don’t feel the need to snack later on. The research backs this up: Protein is certainly more satiating than carbs and even fat. So, have your protein, have your non-starchy veggies, and get your carbohydrates naturally from fruits or vegetables. The key is to avoid making processed or refined carbohydrates, like breads and pastas, the centerpiece of your meals and keep them more protein-forward, instead.   

In addition to satiety, another advantage of centering protein at meals is blood-sugar control. Protein can displace glucose-containing foods that spike blood sugar, and it can reduce blood sugar when you consume it alongside your treats, sweets, and starches. I’m not anti-carb, but I am interested in helping people understand that protein really is going to be the guiding principle that enables you to feel satiated and have a stable blood sugar. When you pair those two huge benefits with plenty of healthy muscle, now you’re really setting yourself up for lasting metabolic health.

Q: What are your thoughts regarding very small eating windows — for example, one meal a day (OMAD)? How do these fasting protocols mesh with protein intake?

A: Many people love OMAD because they find that the length of the fast and the exceptionally short eating window (time for a single meal) enables them to easily shed pounds of body weight. I am a big fan of OMAD, but I do not consider it a great “daily driver” fasting protocol.

OMAD makes hitting an optimal protein intake target exceptionally challenging. If you weigh over 100 pounds, you’re much more likely to miss your protein goals if you follow OMAD on consecutive days. You may be able to meet the RDA for protein, but we all know that metric does not reflect ideal intake, especially with aging. 

OMAD can be an effective strategy for intermittent or occasional use. I find that OMAD is great for travel, vacations, or celebrations, but I don’t recommend it clinically as a foundational approach. It’s absolutely necessary that people balance their nutrition needs with their fasting or time-restricted feeding approach. Well-rounded nutrition balances fasting and feeding, and protein is a crucial piece of striking that balance.

Tips for Meeting Your Daily Protein Goals 

Getting enough protein should be a top priority when your eating window opens. To do that, consider the following tips that can help you consistently provide your body with the amino-acid building blocks it needs to grow strong and stay healthy.

  1. Know your protein target, so you can aim for and hit it reliably. A quick protein-target calculation is 1 gram per pound of body weight. For more personalized calculations, see Your Complete Guide to Protein.
  2. Know the protein quantities of the foods you regularly eat. For animal protein, 1 oz of meat or cheese, 1 egg, and 2 sardines are all about 7 grams of protein. For plant protein, ½ cup of beans, peas, or lentils are all about 7 grams of protein as well.
  3. If you’re eating at a restaurant, don’t be shy about asking for more protein. Doubling your portion size or adding an additional side of protein can be a quick way to up your intake.
  4. Batch prep your protein ahead of time, so you have it ready when you need it.
  5. Have a protein-rich snack. Hard-boiled eggs, canned sardines or tuna, Greek yogurt, and nuts are easy, protein-packed snack options.

Wrap Up

As Cynthia has demonstrated, you have the power to maximize your health through habits like intermittent fasting and ensuring you meet your nutrition needs (especially protein!). For more practical wisdom and education about living a healthy lifestyle, please visit Cynthia’s website, follow her on social media, subscribe to her Everyday Wellness Podcast and YouTube channel, and check out her book, Intermittent Fasting Transformation.

Nicole Grant, RD
Posted in Health & Science

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