Namo Namaha, fellow readers!
She copied the routine. 16:8 fast, black coffee, two meals a day. Just like the podcast said. Except it didn’t work. Her skin dulled. Sleep got worse. The scale didn’t budge. She blamed herself, of course!
But what if it wasn’t her fault? What if she was trying to use software built for an entirely different operating system?
That was the shift that hit me when I discovered the book Fast Like a Girl by Dr. Mindy Pelz — a leading voice in the fasting and functional health space, known for her science podcast and widely-followed YouTube channel.
The book isn’t a diet manual or a trendy hack guide —it’s a fasting guide authored by a woman for the women keeping their metabolic and hormonal health in mind. It challenges the one-size-fits-all approach to fasting that dominates health conversations today.
The Two Different Rhythms: Daily Beats vs. Monthly Symphony
In Fast Like a Girl, Dr. Pelz explains that most popular fasting advice treats the human body the same way regardless of gender. 
According to the book, men typically operate on a straightforward 24-hour hormonal cycle, like a steady drumbeat that repeats daily with testosterone as the primary conductor. This makes consistent daily fasting routines more compatible with male physiology.
Women, on the other hand, experience what could be described as a monthly hormonal symphony. Our hormones dance through complex patterns over approximately 28 days, with entirely different movements each week. Estrogen rises and falls. Progesterone enters and exits. Energy ebbs and flows.
The book suggests that applying the same fasting protocol every day for women is like playing contradictory instruments in a symphony—it’s bound to create a cacophony and disrupt the rhythm.
The author emphasizes that “Marrying the science of fasting to the magic of your hormones is pivotal for your fasting success,” And I’d add—for general health too.
Understanding Fasting Basics
The book begins by explaining what fasting actually means. According to Dr. Pelz, fasting is simply the absence of food for a determined period of time, allowing your body to shift from burning glucose (sugar) to burning fat in the form of ketones. And apparently, it’s this very metabolic shift that underpins most of fasting’s benefits.
Dr. Pelz explains that our ancestors naturally cycled between periods of feasting and fasting based on food availability. Modern life has eliminated these natural cycles, keeping us in a constant ‘fed state‘ that can lead to metabolic inflexibility and health challenges.
Fasting, she says, isn’t about willpower or punishment. It’s about giving your body the rest and space it needs to reset, repair, and realign. Or in her words: “Fasting… It is not a moment of deprivation; it’s a gift you give yourself that will allow your body and brain to recover from the stressors of the modern world.”
The Six Different Types of Fasts
According to Dr. Pelz, successful fasting for women isn’t about finding one perfect protocol—it’s about applying different approaches at the right times. Her book outlines six distinct types of fasts, each serving a different purpose:
- Intermittent Fasting (12-16 hours): An entry point into fasting that helps with weight loss and switching to fat-burning energy. Dr. Pelz notes that ketone production typically begins around the 15-hour mark, improving mental clarity.
- Autophagy Fasting (17-72 hours): A cellular self-repair process that triggers deep cleansing. This process helps with detoxification, brain function, immune support, and hormone balance.
- Gut-Reset Fast (24 hours): This fasting helps repair the mucosal lining of your gut, creating a better environment for beneficial bacteria.
- Fat-Burner Fast (36 hours): A particularly effective fasting for stubborn fat, leading to continued ketone production, reduced cholesterol and inflammation, and helping release stored sugar.
- Dopamine-Reset Fast (48+ hours): A mental health boost fast that repairs and creates new dopamine receptors, improving your brain’s reward pathways.
- Immune-Reset Fast (72+ hours): At this duration of the fast, the body begins to produce new stem cells, creating a powerful healing effect on aging cells and the immune system.
Syncing with Your Cycle: The Fasting Cycle
The breakthrough concept in Fast Like a Girl isn’t just understanding different fast types—it’s learning to sync them with a woman’s monthly hormonal cycle. Dr. Pelz calls this “The Fasting Cycle,” and maps it to four key phases of the menstrual cycle:
- Menstrual (Days 1–5): Lower energy, focus on nourishment and rest.
- Follicular (Days 6–13): Rising estrogen, great for longer fasts and workouts.
- Ovulation (Day 14–16): Peak energy makes this a good time for moderate fasting and higher intensity activities.
- Luteal (Days 17–28): Progesterone rises, and gentler fasting or feasting helps with mood and sleep management.
Women with irregular cycles or no cycles needn’t feel excluded. In the book, Dr. Pelz provides guidance for perimenopause, menopause, and postmenopause, acknowledging that hormonal fluctuations continue throughout a woman’s life, albeit in different patterns. The principles of metabolic flexibility and varied fasting approaches remain relevant, with modifications to accommodate changing hormonal landscapes.
Programming Your Nutrition: Ketobiotic vs. Hormone Feasting
Fast Like a Girl introduces two core eating styles to complement the fasting cycle:
- Ketobiotic: A lower-carbohydrate diet that supports estrogen-dominant phases, enhancing fat-burning and mental clarity.
- Hormone Feasting: A diet that encourages strategic incorporation of complex carbohydrates during progesterone-dominant phases to support optimal mood, sleep, and hormone production.
According to the book, the key is in learning which nutritional approach your body responds to at different times of the month and accordingly fast or feast.
Why Traditional Fasting Often Fails Women
Dr. Pelz identifies several common reasons why traditional fasting approaches often fail women:
- Using the same fasting window every day of the month
- Never varying fasting length (the body adapts and plateaus)
- Ignoring hormonal signals that suggest when to feast vs. fast
- Failing to support detoxification pathways during fasting
- Breaking fasts with foods that spike insulin or inflame the gut
According to Dr. Pelz: “If you feel frustrated at any point on your fasting journey, I want to remind you that there is no such thing as failure when it comes to fasting. If you have a day when you feel like you’ve failed, remind yourself it’s just feedback. Keep learning. Don’t give up.“
The 30-Day Reset Approach
For readers interested in trying this approach, Fast Like a Girl outlines a structured 30-Day Fasting Reset. This program is supposed to be designed to help women experience different fasting lengths and eating styles while learning to listen to their body’s signals.
At its core, the book aims to make fasting both safe and sustainable for women.
Conclusion: A Different Approach for Women
Ultimately, if you’ve been diligently following fasting protocols with disappointing results, perhaps it’s not your fault but rather that you’ve been given instructions designed for a different hormonal system.
Maybe it’s time we realize that a woman’s body design isn’t faulty and doesn’t need to be fixed. We simply need approaches designed for our unique hormonal patterns—ones that honor rather than hamper the monthly rhythms and our mental & physical states.
Dr. Pelz reminds readers: “Never forget, your body is designed to self-heal. It has so many miraculous ways it repairs and resets you every day. When your health feels like a struggle, come back to the Fasting Cycle and ask yourself, ‘Am I living a life that is working with my hormones or against them?’“
While this post only scratches the surface of the concepts presented in Fast Like a Girl, those interested in learning more about fasting specifically tailored to women’s hormonal needs might find value in exploring the complete book.
The core message worth considering is that women are not duplicates of men when it comes to metabolic health. According to Dr. Pelz, our differences aren’t bugs—they’re features. And working with them, rather than against them, might be the approach many women have been searching for.
Have you read Fast Like a Girl or tried cycle-synced fasting? I’m genuinely curious about your experience! Drop a comment below sharing what worked (or didn’t) for you, or reach out through my social channels. Women’s health conversations are always better when shared!
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Until next time, stay blessed, and happy reading! Om Shanti. 🙏
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