The Complete Guide to a 3-Day Fast
My Journey to Fasting: From Skeptic to Believer
Written by Logan Cookingham, Founder & CEO of Vitalize U
(Disclosure: This article contains Amazon affiliate links. As an Amazon Associate, I earn from qualifying purchases. This means I may receive a small commission if you buy through these links, at no additional cost to you.)
I always heard about the incredible benefits of fasting, but for years it remained a distant concept—something I couldn't imagine actually doing. Even as I struggled with chronic illness and came across mounting evidence that fasting could help, I hesitated to take the leap.
That all changed in January 2025 when I suggested to my brother that we try a fast together. To my surprise, he was enthusiastic! We decided on a 72-hour (3-day) water fast, and I was genuinely astonished by the results.
The experience was so transformative that I've done a 3-day fast every month this year (except last month, when I completed my first 5-day fast!). Some of the benefits I've personally experienced include:
- Incredible mental clarity
- Increased mental energy
- Significantly improved sleep quality (sleep score increases by 20+!)
- Decreased resting heart rate (10 BPM lower!)
- Reduced allergies and sinus congestion
- Cleared nasal passages and easier breathing
- A deep sense of calm and tranquility
Maybe you're where I once was—aware of fasting's potential benefits but unsure how to start. In this guide, I'll walk you through everything you need to know about a 3-day fast, including the science behind why it works, what to expect each day, and my tried-and-true preparation and execution strategies.
Understanding What Happens During a Fast
When you temporarily stop eating, your body reclaims a tremendous amount of energy. Your digestive system is one of your body's largest energy consumers, and during a fast, this energy becomes available for cellular repair and regeneration.
Think of it like a kitchen that finally gets time to deep-clean after constantly washing dishes. For those managing conditions like my Mast Cell Activation Syndrome, or anyone with food sensitivities, fasting provides a crucial break from dietary triggers, allowing for a true biological reset.
The Science: Ketosis and Autophagy
Here's what happens in your body during a 3-day fast:
Hours 0-12: Your body depletes its glucose reserves (glycogen stored in your liver and muscles).
Hours 12-48: As glucose diminishes, your body transitions to ketosis—a metabolic state where it burns fat for fuel. This transition period is usually the most challenging. Full ketosis typically activates around the 48-hour mark, though this varies between individuals.
Hours 48-72: Once firmly in ketosis, your body triggers autophagy—a remarkable cellular cleaning process where your body identifies, removes, and recycles damaged cells and components.
If you've never experienced ketosis before, you might encounter the "keto flu"—temporary symptoms like fatigue, irritability, and headaches. During my first fast, I experienced low energy, restless sleep, and minor heart palpitations. But by day three, these symptoms disappeared, replaced by remarkable clarity and energy.
Powerful Health Benefits of Extended Fasting
1. Reduced Inflammation
Fasting significantly lowers systemic inflammation—the root cause of most autoimmune diseases and chronic conditions. I've found that joint discomfort and general body aches noticeably diminish during and after fasting.
2. Immune System Recalibration
Extended fasting helps reset an overactive immune system by promoting a healthy balance of gut bacteria and activating regulatory T-cells that help control immune responses.
3. Cellular Repair and Regeneration
Fasting activates specific longevity genes and protective mechanisms that help repair damaged cells, increasing the production of proteins that protect against cellular stress.
4. Brain Health Enhancement
The neuroprotective effects of fasting are remarkable. Fasting helps your body clear harmful proteins from brain cells, and the ketones produced during fasting are a preferred energy source for the brain—explaining the mental clarity boost.
Your Complete 3-Day Fast Guide: Preparation, Execution, and Recovery
Preparation: Setting Yourself Up for Success
After almost half a dozen fasts, I've learned preparation is key:
1. Dietary Transition
In the 2-3 days before your fast, gradually shift to lower-carb, higher-fat meals. Focus on:
- Healthy fats (avocados, olive oil, nuts, salmon)
- Moderate protein (eggs, poultry, fish)
- Non-starchy vegetables
- Minimal grains, sugars, and starchy foods
This makes the initial phase of fasting significantly easier.
2. Hydration Strategy
Begin intentionally hydrating 48 hours before your fast. I aim for at least 2-3 liters of water on pre-fasting days.
3. Social Support
Consider fasting with a friend or family member (this was a game-changer for me). Feel free to DM me on Instagram (@LoganCookingham) or email me at logan@vitalizeu.com if you'd like to join me on my next fast!
4. For Women: Timing with Your Cycle
Women should consider their menstrual cycle when planning a fast. The entire follicular phase (days 1-14 of your cycle) works well, with the mid to late follicular period (days 7-14) being optimal. Avoid fasting during the luteal phase (days 18-28). If you're pregnant, breastfeeding, or trying to conceive, fasting is not recommended.
5. Clear Your Schedule / Timing
While you can maintain normal activities during a fast, I recommend minimizing stressful commitments, especially during your first extended fast. If possible, schedule your fast during a period when you have flexibility with work and social obligations. I personally do my fasts over the weekend, with my last meal on a Thursday afternoon/evening, and then break it on Sunday afternoon/evening. This timing works well with my lifestyle and allows me to rest more if needed.
During the Fast: What to Expect
As you start your fast, your body will begin depleting its glucose reserves during the first 12 hours or so. Then it shifts to activating ketosis—where your body uses fat as fuel instead of glucose. Here's what you might experience each day:
Day 1
Most people find the first day manageable since your body still has glycogen reserves. You'll likely feel hungry around your normal mealtimes, but it's not overwhelming. Stay busy with light activities and make sure to drink plenty of water with some Celtic Sea Salt added for electrolytes (has all antural trace minerals as well). If hunger hits hard, a cup of black coffee or plain tea can help suppress your appetite.
Day 2
This is usually the hardest day as you're in that transitionary phase to ketosis. For my first fast, I experienced a period of really low energy, restless sleep, and some minor heart palpitations. These are normal as your body adapts to using a different fuel source. Increase your salt intake, rest when needed, and remember—this challenging phase is temporary. A light walk can sometimes help you feel better and accelerate ketosis.
Day 3
I'm so glad I pushed through the second day, because the third day was definitely the best! By now, ketosis is in full effect, autophagy is activated, and most people (including myself) notice:
- Significantly reduced hunger
- Incredible mental clarity
- Improved energy levels
- A sense of accomplishment
By the end of my first 3-day fast, I was so energized that I was tempted to continue for another day because I felt so amazing. Keep up with your electrolytes, enjoy the mental clarity, and prepare for properly breaking your fast.
Fasting Essentials to Remember
Hydration Is Crucial
- Add high-quality Celtic Sea Salt to water which has all the essential trace minerals needed (my personal go-to)
- Aim for 2-3 liters of water daily
- Space your water consumption throughout the day
What's Allowed During a Fast
While opinions vary, these are generally acceptable:
- Plain water (always)
- Black coffee (unsweetened)
- Plain tea (herbal or regular, unsweetened)
- Apple cider vinegar (1-2 tablespoons in water)
- Electrolytes and minerals
For my personal fasts, I stick to water with Celtic Sea Salt and occasionally black coffee in the morning. More recently, I've also experimented with replacing coffee with caffeine pills which has helped my gut more during the fasting process (I use these ones as it's pure caffeine, zero additives)
Supplements and Medications
I've experimented with taking supplements during fasts but now pause my supplement routine to maximize fasting benefits.
Medications are different! Always consult your healthcare provider before altering any medication schedule.
Physical Activity
Listen to your body, but generally:
- Walking and light stretching are beneficial
- Avoid intensive cardio or heavy weight training
- If you feel weak or dizzy during activity, stop and rest
When to Break a Fast Early
While some discomfort is normal, certain signs indicate you should end your fast:
- Severe dizziness or lightheadedness that doesn't improve with salt intake
- Persistent nausea or vomiting
- Irregular or racing heartbeat
- Extreme weakness
Breaking Your Fast: The Critical Transition
Breaking a fast properly is just as important as the fast itself. After three days without food, your digestive system needs a gentle reintroduction.
I'll usually break my fast with bone broth - you can also use vegetable broth as a plant-based alternative. Keep your portion small, around 1 cup maximum.
After waiting about an hour, I'll eat something very clean like steamed vegetables and chicken or fish. Keep it basic with just salt and avoid spices as they might cause digestive discomfort. The key is simplicity and gentleness.
Be careful not to overeat. Your stomach hasn't had food in it for a while, so you won't need as much food as you might think. It's better to eat less than you think you need rather than risking discomfort from eating too much too soon.
The day after your fast, continue emphasizing whole, unprocessed foods and pay attention to how different foods make you feel. This heightened awareness is one of the gifts that fasting gives you - a reset relationship with food and greater bodily intuition.
Common Mistakes to Avoid:
- Eating too much too quickly (causes stomach discomfort and potentially dangerous refeeding syndrome)
- Breaking fast with high-carb or sugary foods (triggers insulin spikes and inflammation)
- Complex or spicy foods (can irritate the digestive system)
- Alcohol (particularly harsh after a fast)
Conclusion: Your Fasting Journey
The 3-day fast has become a cornerstone of my health routine, delivering benefits I couldn't have imagined when I was still on the fence about trying it. While challenging at times, the clarity, energy, and health improvements make it absolutely worthwhile.
Remember that fasting is a practice that improves with experience. Your first fast is about learning—both about the process and about your body's unique responses.
I hope this guide helps you navigate your own fasting journey with greater confidence and success. If you have questions or want to share your experience, please reach out to me on Instagram (@LoganCookingham) or email me at logan@vitalizeu.com.
Here's to your health transformation through the ancient but powerful practice of fasting!
Note: While fasting offers significant benefits for many people, it isn't appropriate for everyone. Always consult with your healthcare provider before beginning any extended fast, particularly if you have existing health conditions, are on medications, are pregnant or breastfeeding, or have a history of disordered eating.