The Complete Guide to Fasting (Dr. Jason Fung): Book Overview
✨ Key Takeaways
- Learn the best practices of intermittent fasting for optimal health.
- Understand how to track your fasting windows effectively.
- Discover the science-backed metabolic benefits of fasting.
In This Article
- The Ultimate Manual for Therapeutic Fasting
- Fasting as an Ancient Healing Tradition
- ⏱️ Your Digital Fasting Assistant
- Practical Protocols for Every Goal
- Troubleshooting the Side Effects
- Key Takeaways from The Complete Guide
- Ready to Heal Your Metabolism?
- Frequently Asked Questions
- Does It Break Your Fast? Interactive Drink Checker
- 📖 Related Fasting Guides & Research
The Ultimate Manual for Therapeutic Fasting
While Dr. Jason Fung’s first book, The Obesity Code, focused on the deep endocrinology and theory of why we get fat (insulin resistance), his follow-up book, The Complete Guide to Fasting, co-authored with Jimmy Moore, is all about execution. It is the practical, hands-on manual for anyone looking to use fasting as a therapeutic tool to heal their body.
Whether you want to lose a few stubborn pounds, reverse type 2 diabetes, or explore the longevity benefits of extended water fasts, this book provides exact schedules, troubleshooting tips, and medical protocols to do it safely and effectively.
Expert Take (Aly Owen): “This book is the gold standard reference manual. Whenever a client asks me a specific question—like how to fast if they are on medication, or what to do if they get a headache on day two of a fast—the answers are always found in this guide.”
Fasting as an Ancient Healing Tradition
Dr. Fung begins by removing the modern stigma associated with fasting. He points out that for thousands of years, fasting was considered a natural, healing practice in almost every major religion and culture. It is only in the last 50 years—with the advent of the food industry’s push for 3 meals and 3 snacks a day—that fasting became viewed as “starvation.”.
The book clearly distinguishes between starvation (involuntary, uncontrolled absence of food) and fasting (voluntary, controlled abstinence for spiritual, health, or other reasons). Your body is perfectly designed to survive and thrive during periods without food by seamlessly switching to burning its own fat stores.
⏱️ Your Digital Fasting Assistant
Ready to implement Dr. Fung’s protocols? Download our Simple Intermittent Fasting Tracker app on iOS. Choose from pre-set schedules like 16:8, 24-hour, or extended fasts, and track your fat-burning stages in real-time.
Practical Protocols for Every Goal
The Complete Guide to Fasting excels in its detailed breakdown of different fasting protocols. It does not force a one-size-fits-all approach. Instead, it offers options based on your specific health goals:
- 16:8 or 20:4 (Daily Fasting): Ideal for steady, long-term weight loss and general health maintenance.
- 24-Hour and 36-Hour Fasts (Monk Fast): Recommended for breaking through weight loss plateaus and reversing severe insulin resistance.
- Extended Fasts (3 to 7+ Days): Used therapeutically for massive autophagy, immune system resetting, and rapid reversal of type 2 diabetes (must be done under medical supervision if on medication).
Troubleshooting the Side Effects
One of the most valuable sections of the book deals with the common side effects of fasting and how to manage them. Dr. Fung and Jimmy Moore address real-world challenges that cause people to quit prematurely.
For example, if you experience headaches or muscle cramps during a fast, the book explains that this is usually due to sodium and electrolyte depletion (as fasting lowers insulin, which causes the kidneys to excrete water and sodium). The simple fix? Drink some bone broth or add a pinch of sea salt to your water. They also provide practical advice for dealing with hunger waves, dizziness, and constipation.
Key Takeaways from The Complete Guide
- Bone Broth is Your Friend: On longer fasts, homemade bone broth provides essential electrolytes and makes the fast highly sustainable without breaking the benefits.
- Feast Properly: Breaking an extended fast is just as important as the fast itself. Start with a small, easily digestible meal (like a handful of nuts or a small salad) to avoid gastrointestinal distress.
- Don’t Force It: If you feel unwell, dizzy, or nauseous (beyond normal hunger waves), break the fast. Fasting should be therapeutic, not torturous.
- Combine with LCHF: Fasting is most effective when combined with a Low-Carb, High-Fat (LCHF) or Ketogenic diet, as both strategies keep insulin levels low.
Ready to Heal Your Metabolism?
Put the science of Dr. Fung into practice today. Get customized schedules, track your health markers, and stay motivated with the Simple Fasting App.
Frequently Asked Questions
Is fasting safe for type 2 diabetics?
Yes, Dr. Fung uses fasting extensively in his clinic to reverse type 2 diabetes. However, if you are on medications (especially insulin or blood sugar-lowering drugs), you MUST consult your doctor before fasting, as your medication doses will need to be adjusted to prevent severe hypoglycemia.
Will fasting slow down my metabolism?
No. The book cites numerous studies demonstrating that while daily caloric restriction slows the metabolism, intermittent and extended fasting actually boosts basal metabolic rate due to increased adrenaline and noradrenaline.
What can I consume during a fast according to this guide?
Dr. Fung is slightly more lenient than the strict “clean fast” crowd. He allows water, black coffee, plain tea, and, for those struggling, small amounts of bone broth or a tiny splash of heavy cream in coffee to help compliance.
Does It Break Your Fast? Interactive Drink Checker
Search or filter any drink to verify its impact on insulin, ketosis, and cellular autophagy in real-time.
Pure black coffee does not break a fast. Its high chlorogenic acid content actually accelerates cellular autophagy and fat oxidation.
Unsweetened green tea contains potent EGCG catechins that stimulate AMPK and enhance fat breakdown while keeping insulin completely flat.
Pure water is the gold standard for fasting. It assists liver kidney clearance without causing any metabolic disruption.
Squeezing a wedge of lemon adds trace vitamin C and potassium. With fewer than 3 calories, it will not trigger an insulin spike or break fasting.
1-2 tablespoons diluted in water helps stabilize gastric emptying, suppresses appetite, and has zero negative effect on fasting.
Zero caloric value keeps ketosis intact, but artificial sweeteners (sucralose, acesulfame K) may trigger sweet cravings or cephalic phase insulin release.
Excellent for "dirty fasting" or multi-day electrolyte preservation. However, its amino acid content (glycine, proline) pauses mTOR autophagy.
Pure fat keeps you in ketosis, but the incoming calories prevent cellular autophagy and cause the body to burn dietary fat before body fat.
Lactose is a dairy sugar that immediately raises blood glucose and insulin, stopping lipolysis and breaking your fast within minutes.
High fructose concentration floods the liver, triggers rapid insulin release, and instantly terminates both ketosis and autophagy.
Although rich in potassium, natural coconut water contains 9-11 grams of natural carbohydrates per cup, which breaks your fasting window.
The liver halts all fat oxidation and ketone synthesis to prioritize metabolizing toxic alcohol byproducts, severely stressing your metabolism.
Track daily hydration, fasting windows, and get notified when entering peak autophagy with FastingTracker.
Interactive Autophagy & Cellular Renewal Tracker
Drag the slider to see what metabolic transformations occur inside your cells hour by hour.
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📖 Related Fasting Guides & Research
📚 Scientific Studies & Medical References (5 Sources) ▼
FastingTracker adheres to strict editorial standards, citing peer-reviewed clinical trials and authoritative medical institutions.
- New England Journal of Medicine (2019): de Cabo R, Mattson MP. Effects of Intermittent Fasting on Health, Aging, and Disease. N Engl J Med. 381(26):2541-2551. PubMed 31881139 • DOI
- Cell Metabolism (2014): Levine ME, Suarez JA, Brandhorst S, et al. Low Protein Intake and Periodic Fasting Promote Longevity and Autophagy. Cell Metab. 19(3):407-417. PubMed 24606898 • DOI
- Obesity (Silver Spring, 2018): Anton SD, Moehl K, Donahoo WT, et al. Flipping the Metabolic Switch: Understanding and Applying Health Benefits of Fasting. Obesity. 26(2):254-268. PubMed 29086496 • DOI
- Annual Review of Nutrition (2017): Patterson RE, Sears DD. Metabolic Effects of Intermittent Fasting. Annu Rev Nutr. 37:371-393. PubMed 28715993 • DOI
- Autophagy (2010): Alirezaei M, Kemball CC, Flynn CT, et al. Short-term fasting induces profound neuronal and systemic autophagy. Autophagy. 6(6):702-710. PubMed 20534972 • DOI
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Personal Fasting Protocol Finder
Answer 3 quick questions to calculate your optimal, science-backed fasting and eating windows.
1. What is your primary health goal?
2. What is your fasting experience?
3. What matches your daily lifestyle?
16:8 Lean Protocol
🥗 Best Meals to Break Your Fast
Gentle, nutrient-dense dishes designed to avoid insulin spikes and digestive discomfort when exiting your fast.
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