The hormone-smart way to fast.

Fasting is a powerful longevity tool for women—if you get the strategy right.

Last month I wrapped up my annual 5-day fast (this year, a fasting-mimicking diet—more on that below).

Not for weight loss. Not to “detox.” But because fasting done right can be one of the most effective ways to:

• Induce cellular repair
  

• Reset metabolic health
  

• Lower inflammation
  

• Rebalance hormones
  

• Reduce chronic disease risk
  

Fasting is also one of the most misunderstood tools for women.

The internet loves to argue: “Is fasting bad for women’s hormones?” But that’s the wrong question. The right one is: What kind of fasting, for which woman, and when?

Let’s break it down.

🤓 What to know: Fasting triggers the magic of autophagy.

For weight loss, fasting is less studied than calorie restriction. But for longevity, we know that fasting for 16+ hours can switch on autophagy—your body’s cellular recycling program (International Journal of Molecular Sciences, 2025).

Autophagy clears damaged components inside cells, removes “junk” proteins, and stimulates repair. Think of it as a deep clean at the microscopic level.

The benefits are wide-reaching:

🧠 Brain health

• Clears misfolded proteins like beta-amyloid and tau (linked to Alzheimer’s)

• Boosts BDNF, a compound that supports memory and mood

🎗 Potential cancer prevention

• Eliminates precancerous cells

• Lowers IGF-1 (a growth signal linked to cancer)

• Reduces oxidative stress + inflammation

• Enhances DNA repair

🔥 Lower inflammation

• Removes damaged mitochondria that create inflammatory free radicals

• Downregulates pro-inflammatory pathways like NF-kB

❤️ Cardiovascular health

• Improves lipid metabolism

• Enhances HDL/LDL ratios

• Reduces vascular inflammation

💪 Metabolic health

• Improves insulin sensitivity

• Stabilizes blood sugar

• Reduces liver fat accumulation

🌱 Stem Cell Activation

• Prolonged fasts (48–72 hrs) regenerate immune + gut stem cells

⚠️ Why Women Need a Different Fasting Strategy

Women have tighter hormonal feedback loops and store more body fat than men. That means aggressive fasting can cause:

• Muscle loss

• Blood sugar crashes

• Hormone disruption

Your baseline matters.

If you’re already metabolically fit, too much fasting can backfire. But many women (myself included) sit at a desk most of the day and aren’t burning through glycogen regularly. For women with impaired glucose control, PCOS, menopause symptoms, or metabolic syndrome, fasting can help reset hormonal imbalances and restore metabolic health (Disease Markers, 2022).

💪 What to do: Start with a 16+ hour intermittent fast followed by 30g of protein.

Fasting isn’t “bad” for women. But fasting without a strategy can be.

My personal protocol:

• 16-hour intermittent fast (7 PM–11 AM) 3–4 days/week → burns glycogen, shifts my body into fat-burning mode, gentle enough that I don’t get hangry

• Break fast with 30g protein → enough to trigger muscle protein synthesis, which is most effective when you hit a threshold of leucine (~25–35g of high-quality protein) 

• 1x/year 5-day fasting sprint → deeper autophagy, immune reset, inflammation reduction (especially important for my positive ANA marker, a marker of autoimmune activity)

4 fasting styles to explore: 

🕜 Intermittent Fasting (aka time-restricted eating)

• Easy entry point, helpful for blood sugar regulation and mild caloric control. 

• 12-15 hours: fat burning begins and insulin sensitivity improves. 

• 16+ hours: autophagy begins. 

Try a 7pm to 11am fast 3x per week. 

🥩 Ketogenic Diet

• High-fat, very low-carb diet—70-80% calories from fat, 10-20% protein, and 5-10% carbs—shifts the body into ketosis (i.e. burning fat instead of glucose for fuel). 

• Works best when paired with blood (most accurate) or urine testing (least accurate) to confirm your body is in ketosis.

• Can worsen high cholesterol in some people. 

• One small case study found that a ketogenic diet significantly improved symptoms in patients with major depressive disorder (Frontiers in Nutrition, 2024)

Talk to your doctor about your cardio labs before trying. 

🚰 Nothing-But-Water Fast

• 4-12 hours: blood sugar and insulin drop

• 12-16 hours: ketosis starts

• 16-24 hours: autophagy begins, inflammation lowers, fat metabolism and growth hormone rises

• 24-36 hours: autophagy intensifies and cognitive and immune function may improve

• 48-72 hours: stem cell renewal in the gut, blood, and immune system 

I don’t recommend more than 5 days of fasting at a time.

🥗 Prolon (fasting-mimicking diet):

• This year I tried Prolon’s 5-Day Fasting Mimicking Program, a pre-packaged meal kit designed to induce ketosis and autophagy while you’re still eating.

• Designed by researchers at the University of Southern California to induce a state of "cellular fasting.” 

• Allows you to eat pre-packaged food without activating nutrient sensing pathways (IGF-1, mTOR, and PKA). 

• Proven to reduce body fat, improve blood pressure, and lower IGF-1 (Science, 2017).

• Super convenient. 

Great for first-timers or those who can’t tolerate water fasting. 

🚫 When to avoid fasting

Burnout/adrenal dysregulation → Fasting activates stress pathways (AMPK and cortisol), which can worsen symptoms of hypothyroidism and adrenal dysregulation.

Trying to conceive → can lower LH and estradiol, disrupting ovulation or causing missed periods

(Note: this assumes you’re already metabolically healthy. Poor blood sugar control, metabolic syndrome and diabetes can all worsen fertility and conditions like PCOS. If intermittent fasting improves your blood sugar control, it may potentially help fertility.)  

Pregnant or breastfeeding → higher calorie needs; may affect milk supply or fetal development

Perimenopause/menopause → research is mixed; may be especially effective for weight loss in post-menopausal women (Nutrition and Healthy Aging, 2017), but could cause a drop in estrogen precursor DHEA (Obesity, 2022). 

(My POV: even if a short-term fast temporarily disrupts hormones, a 5-day fast once a year to improve autophagy and reduce inflammation is unlikely to have a long-term effect on hormone levels.) 

Low muscle mass (<27%) or BMI (<18.6) → higher risk of muscle loss unless paired with adequate protein and resistance training

On GLP-1s → risk of dangerously low blood sugar and GI distress

History of disordered eating → even structured fasting can reinforce harmful food patterns

⚡️ Quick hits

🎧 Estrogen is the new longevity drug

I joined the Global Wellness Institute podcast to talk biomarkers, GLP-1s, and why estrogen matters more than ever.

Listen here!

🥦 Real food = double the weight loss

If you needed more proof UPFs are bad for you, a new study found people who cut ultra-processed foods lost 2x more weight. Whole foods increase satiety and reduce overall calorie consumption while improving body composition.

My favorite recipes for addictive veggies. 

🐟 Cod bars?

David (of protein bar fame) is now selling vacuum-sealed wild cod fillets. Not sure how my stomach feels about this, but it’s at least a real-food upgrade from their “frankenbars.

I still prefer Epic meat bars on-the-go. 

💛 The Momgevity Files

This week, I pulled a tick off my leg and prescribed myself a single 200mg dose of doxycycline to prevent Lyme disease.

I’ve lived in Lyme-heavy zones, treated patients with it, and seen how disruptive it can be—so I take it seriously.

I was upstate with some mama friends, where Lyme anxiety is running high. One won’t even let her kids walk in the grass. I get it… but I’m not spending the summer indoors. I’ll sit in the grass and let my kid run barefoot—then we do a tick check every. single. time.

This week, both my three-year-old and I ended up with bites. Here’s what the CDC says: if a deer tick has been attached long enough, a single 200mg dose of doxycycline within 72 hours can lower Lyme risk by 87%.

For my son (45 lbs of giant toddler—thanks, bone broth + Parsley protein powder) that meant a one-time 100mg dose. Yes, kids can take doxy as prevention, but it’s weight-based—so talk to your pediatrician.

My take: If you get a tick bite, take the antibiotics and move on. Herbal antimicrobials can be amazing for chronic Lyme, but for acute prevention, doxy is fast, effective, and low-risk.

In the wellness world, it’s easy to slide into “anti-medication” mode. But I’m a both/and girl:

• Eat real food
  

• Avoid toxins
  

• Move daily
  

• And yes—use pharmaceuticals when they’re the best tool for the job

You can be anti-inflammatory and pro-antibiotic when the moment calls for it.

Stay strong, stay curious, and breathe,

Robin

As always, this newsletter is for informational and educational purposes only and is not intended as medical advice. Always consult your healthcare provider before making any health decisions or changes to your treatment plan.