Fasting: How to Fast, Fasting Best Practices, & Fasting For Women 101

Fasting has been practiced for thousands of years as a spiritual discipline, a survival rhythm, and a natural part of how humans were designed to live. 

While it used to be an intuitive part of everyday life, today we understand that fasting is more than just abstaining from food. It’s a powerful tool to support cellular repair, hormone balance, and longevity when done thoughtfully. 

In the following article, we’ll take a closer look at best practices of fasting:

• How to fast in a way that is effective and gentle
• What to eat going into a fast and coming out of one
• What to expect during and after a fast
• Benefits of a fast by the hour
• Fasting for women 

 

What Is Fasting?

At its core, fasting means taking a deliberate break from eating to allow the body to reset, repair, and restore. Instead of constantly digesting food, your body shifts into a state of deep maintenance and renewal. It’s a process that promotes fat burning, cellular cleanup (also called autophagy), and hormone optimization.

In modern life, fasting might look like shortening your eating window (intermittent fasting) or occasionally abstaining from food for 24-72 hours while maintaining hydration and electrolytes.

 

My Journey With Fasting

My personal relationship with fasting began when I was diagnosed with cancer. As part of my integrative therapy, I used ketosis and fasting to help “starve” cancer cells of their primary fuel, which is glucose, while supporting my body’s natural repair systems. 

That experience reshaped how I view nutrition, metabolism, and resilience. Fasting isn’t punishment. It’s actually partnership and cooperation with your body’s innate intelligence. When done correctly, it is a means of supercharging detoxification and healing. 

 

Nutrition: Easing Into a Fast and Coming Out of One

If you’ve never fasted before, start slow. 

I always suggest you begin with intermittent fasting, gradually shortening your eating window from 12 hours to 10 or 8 hours (a 14:10 or 16:8 pattern).

When you’re entering into a longer fast (24-72 hours), you want to prepare your body:

• Hydrate well: Drink 3-4 liters of filtered water per day. 
• Use electrolytes or mineral salt: Ensure you’re maintaining proper hydration and mineral status. I suggest a pinch of TDW Mineral Salt in warm water, Quinton minerals (found on Fullscript). or TDW Electrolytes daily in order to maintain balance. *Note: I do not suggest TDW Electrolytes during a fast due to the organic fruit juice powder component, but TDW Mineral Salt and Quinton are still excellent choices while fasting. 
• Ease into it with nutrient-dense foods: In the days leading up to your fast, focus on nutrient dense and easy-to-digest foods like bone broth (use code TAYLORDUKES), cooked vegetables, and healthy fats (avocado, olive oil, wild caught fish, etc.).

When breaking your fast:

• Start with bone broth or steamed veggies to break your fast. I love drinking FOND bone broth (use code TAYLORDUKES) and making my green gut healing vegetable soup. Then, add healthy fats and clean proteins. Stick with the same types of nutrient dense and easy-to-digest foods you ate while entering into your fast for the first 12-24 hours coming out of your fast. 
• Avoid sugar, processed foods, or heavy carbs for at least 24 hours.

 

Dos and Don’ts of Fasting

DO:

• Hydrate with 3-4 liters of filtered water and minerals daily – a pinch of TDW Mineral Salt or Quinton (found on Fullscript). 
• Move gently (walking, stretching, breathwork).
• Rest and support your nervous system.
• Reflect – fasting can be as much mental and spiritual as it is physical.
• Start your fast in the evening (6-7pm) to sleep through the first 12-14 hours of your fast.
• Herbal teas like dandelion or nettle support liver and lymph.

DON’T:

• Over-exercise or use saunas (which add detox stress).
• Push through extreme fatigue or dizziness.
• Break your fast with sugar or processed foods.

 

What Happens During a Fast?

Every hour of your fast unlocks new benefits. Here’s a simplified timeline based on the body’s physiological changes:

Time	What’s Happening in the Body	Key Benefits
12 hours	Blood sugar drops; body switches from glucose to fat for fuel; glycogen depletes	Insulin drops, digestion rests, early cellular repair begins
24 hours	Autophagy begins; damaged cells start being cleared; ketone production rises	Cellular cleanup and detox pathways activate
36 hours	Deep ketosis; ketone production increases even more	Enhanced fat burning and brain clarity
48 hours	Immune system reboot; inflammation decreases	Regeneration of immune cells, improved insulin sensitivity
72 hours	Growth hormone rises; stem cell production peaks; mitochondria regenerate	Full cellular reset and reduced inflammation

 

What Is “Keto Flu” (and How to Ease It)

When your body transitions from burning sugar to burning fat for fuel, called ketosis, you might experience temporary symptoms known as “keto flu.” This can include fatigue, headache, irritability, or lightheadedness, often within the first 24-72 hours of fasting.

These symptoms are simply signs that your body is recalibrating its metabolism and electrolyte balance. To ease the transition:

• Hydrate deeply and add minerals, if you haven’t already.
• Rest and sleep more than usual to support recovery.
• Take an Epsom salt bath to replenish magnesium and relax your muscles.
• Try dry brushing or castor oil packs to support detox pathways and lymphatic flow.
• If you must break your fast, sip bone broth for gentle nourishment and steady energy.
  

With proper hydration, mineral support, and rest, the keto flu typically resolves within a day or two, leaving you with renewed energy and mental clarity.

 

What to Expect & Benefits of Fasting

Fasting isn’t just a physical reset. It’s a full body and mind recalibration. As your body shifts from digesting to deep repair, you may feel a mix of sensations that reflect powerful internal changes.

Physically, you might notice waves of fatigue, lightheadedness, or even heightened energy as your body transitions from glucose to fat for fuel. Behind the scenes, your cells are hard at work:

Your body is optimizing mitochondrial function, cleaning up damaged cells, and making room for new, healthier ones – that’s autophagy in action. Some “symptoms” of fasting may include:

• Chills or feeling cold, since your body conserves energy and blood flow shifts.
• Muscle soreness or weakness as your body releases stored water and minerals.
• Bad breath or “metallic taste” – a sign of ketone production.
• Increased urination as glycogen (which holds water) is burned off.
• Heightened smell or taste sensitivity, as digestion and detox pathways recalibrate.

Mentally, fasting often brings a surprising sense of clarity once you move past the early hunger cues. Many people report sharper focus, calmer thinking, and an overall feeling of “lightness.”

Emotionally, it can be both grounding and revealing. Without constant eating cues, emotions may rise to the surface – a natural part of your body and mind recalibrating. Approach it with curiosity, not judgment. Give yourself grace for what you feel.

Throughout the process, remember that your liver and lymphatic system are working overtime, flushing toxins and supporting regeneration. That’s why rest, hydration, and gentle movement are essential. Prioritize sleep, as that’s when your body does its deepest repair work.

Fasting is less about restriction, and more about renewal. And the benefits are big:

• Reduces inflammation and supports detoxification
• Improves insulin sensitivity and blood sugar balance
• Supports gut healing by resting the digestive tract
• Promotes longevity via autophagy and mitochondrial repair
• Boosts immune resilience and may help target abnormal or precancerous cells
• Improves skin, energy, and mental clarity through reduced oxidative stress

 

An Ancient and Biblical Practice

Fasting is one of the oldest healing practices known to humanity, woven into both our biology and our history. Our hunter-gatherer ancestors naturally fasted through cycles of feast and famine, allowing the body to rest, reset, and adapt.

But fasting isn’t just physical. It’s deeply spiritual. Throughout the Bible, fasting is a way to seek clarity, strengthen faith, and draw closer to God. It was never about deprivation, but about  creating space to quiet distractions and realign with what truly sustains us.

“Man shall not live by bread alone, but by every word that comes from the mouth of God.” -Matthew 4:4

We see this modeled throughout the Bible:

• Jesus fasted for 40 days before beginning His ministry (Matthew 4:1–2)
• Moses fasted while encountering God on Mount Sinai (Exodus 34:28)
• Esther called for a fast in a moment of courage and surrender (Esther 4:16)
• The early church fasted when seeking guidance and direction (Acts 13:2–3)

Again and again, fasting is used as a pathway to clarity and deeper connection.

When approached with intention, fasting can:

• Deepen your relationship with God
• Create space for prayer and discernment
• Strengthen discipline and reliance on faith over flesh
• Bring clarity in seasons of uncertainty

There’s something powerful that happens when physical stillness meets spiritual intention. As your body shifts into repair mode, your spirit often becomes more receptive. In that way, fasting is less about restriction and more about realignment.

 

Who Can Benefit from Fasting

When done safely, fasting can be particularly beneficial for those with:

• Autoimmune or inflammatory conditions
• Cancer or metabolic disorders (with medical oversight)
• Gut dysbiosis or SIBO
• Skin issues (acne, eczema)
• High blood pressure or metabolic syndrome

 

Who Should Proceed With Caution

Avoid or modify fasting if you:

• Have adrenal fatigue or cortisol dysregulation – focus on nervous system healing first
• Struggle with eating disorders – fasting can be triggering
• Are pregnant or breastfeeding
• Have diabetes or thyroid conditions – seek professional guidance before fasting
• Those who are under 18 or over 60

If fasting increases stress or worsens sleep, mood, or energy, it’s a sign to scale back and support the adrenals and thyroid before trying again.

 

Fasting for Women: What You Need to Know

Fasting affects women differently due to hormonal rhythms. Understanding your cycle phase can make fasting safer and more effective:

Cycle Phase	Fasting Guidance	Why
Days 1–5 (Menstrual)	Light fasting only	Energy is lower; body needs nourishment
Days 6–12 (Follicular)	Best time for longer fasts (36–72 hours)	Estrogen rising → body resilient to stress
Days 13–15 (Ovulation)	Use caution	Hormones peak; fasting may disrupt ovulation
Days 16–28 (Luteal)	Avoid fasting	Progesterone needs calories; fasting may cause fatigue or hormone imbalance

 

The best time for any women to fast is during their follicular phase, which is days 6-12 of a normal 28-day cycle. This is when the body is most resilient to stress. 

If you’re perimenopausal, reserve longer fasts for low-stress times when sleep and mood are stable. Anecdotally, women who fast during perimenopause may see the most benefit. Some even report seeing greater regularity in their cycles after fasting. 

Note that whether you are cycling regularly or perimenopausal, if you rush into fasting without preparing the body – or if you fast during times of high stress and low resiliency – fasting can trigger even more stress, higher cortisol, and increased symptoms. It’s incredibly important to take a gradual and gentle approach to fasting, especially for women!

In menopause, fasting is often better tolerated since hormones fluctuate less. Start with shorter windows (14:10 or 16:8) and build up slowly.

 

Fasting for Cancer: A Metabolic Approach to Healing

Fasting can be a powerful metabolic therapy to support the body during cancer prevention or treatment. It is not a replacement for medical care, but a way to strengthen your body’s resilience and create an internal environment where cancer struggles to thrive.

When you fast, your body switches from burning sugar (glucose) to burning fat for fuel. Cancer cells depend heavily on sugar, but they can’t efficiently use fat or ketones. Meanwhile, your healthy cells adapt easily, becoming stronger and more stress-resistant. This metabolic shift helps to:

• Starve cancer cells of their primary fuel source.
• Lower insulin and IGF-1, which are growth signals that promote tumor development.
• Boost immune function, helping your body identify and destroy abnormal cells.
• Activate autophagy, the process that clears out damaged or precancerous cells.

Short-term fasting, especially 48 to 72 hours before chemotherapy, may help protect healthy cells, reduce side effects like nausea and fatigue, and enhance the effectiveness of treatment. Some integrative protocols include fasting one day before, the day of, and the day after chemotherapy to help the body tolerate therapy better.

Fasting also reduces inflammation, angiogenesis (the formation of new blood vessels that feed tumors), and the mTOR and IGF pathways, both of which fuel cancer cell growth. In essence, fasting helps your body shift from growth mode into repair mode.

For those in remission or seeking prevention, pairing intermittent fasting (16-18 hours) several days per week with longer fasts (3-5 days) every few months can support deep immune rejuvenation and mitochondrial repair.

Fasting doesn’t cure cancer, but it empowers the terrain of your body to resist disease, optimize treatment response, and restore cellular integrity.

 

Fasting with Thyroid Issues: Proceed Mindfully

Fasting can be supportive for thyroid health, but it requires a thoughtful, individualized approach. Your thyroid is deeply tied to your body’s stress response and metabolism, and fasting (especially prolonged or aggressive fasting) can influence both.

When done wisely, fasting may reduce inflammation, improve gut and liver function (where thyroid hormone conversion occurs), and enhance cellular sensitivity to thyroid hormones. However, if your cortisol levels are high or your adrenals are depleted, fasting can backfire by increasing stress hormones, which may inhibit thyroid conversion (T4 → T3).

Here are some best practices for fasting with thyroid considerations:

• Start slow: Begin with gentle intermittent fasting (12:12 or 14:10) and gradually increase your fasting window if tolerated.
• Support your adrenals: Prioritize rest, hydration, sleep, and mineral balance.
• Include electrolytes and bone broth during fasting windows to prevent added stress on the body.
• Avoid fasting during high-stress periods or when sleep is disrupted – these are times when your body needs nourishment, not restriction.
• Check thyroid levels regularly, and work with a practitioner to ensure your hormones are optimized before attempting longer fasts.

Fasting can help “reset” thyroid signaling when done safely – improving cellular metabolism and reducing inflammation – but it should always feel supportive, not depleting. If you notice worsening fatigue, anxiety, hair loss, or temperature sensitivity, it’s time to pause and nourish.

The goal isn’t to push harder. It’s to partner with your body’s natural rhythms so healing happens from a place of balance, not burnout.

 

The Bottom Line

Fasting can be one of the most powerful tools for healing and longevity when done with intention, education, and respect for your body’s design. Start small, nourish deeply, and always listen to your body’s cues.

Whether your goal is cellular repair, metabolic health, or spiritual growth, fasting offers your body permission to heal.

Recommended resources:

• Dr. Mindy Pelz – expert on fasting for women’s hormonal cycles
• Dr. Jason Fung – leading voice on metabolic fasting
• Megan Ramos – integrative nutritionist and fasting educator