The Complete Guide to Fasting by Dr Jason Fung: Review
For a lot of people, this is the book that made fasting feel like medicine rather than a fad. Dr Jason Fung teamed up with health podcaster Jimmy Moore to write the closest thing the field has to a practical manual for longer, therapeutic fasting.
Authors: Dr Jason Fung, MD, with Jimmy Moore · Publisher: Victory Belt Publishing, 2016 · Length: about 304 pages
What The Complete Guide to Fasting covers
Fung’s central argument is about insulin. Keep insulin low, he argues, and the body will burn fat and metabolic health will improve, which is where fasting comes in. The book explains that physiology and then applies it to weight loss and to reversing type 2 diabetes.
The practical half is thorough. There are concrete protocols for intermittent, alternate-day, and extended multi-day fasts, clear guidance on who should and should not fast, and answers to the questions that stop people: how to manage hunger, what fluids are allowed, how to break a long fast. Moore’s contribution keeps the medical content readable and adds a personal thread. It also includes sample schedules and fluid recipes.
Who it’s best for
Readers who want a thorough, protocol-driven how-to for longer therapeutic fasting, including anyone approaching it for a metabolic condition under medical supervision.
Key takeaways from The Complete Guide to Fasting
- Lowering insulin is the mechanism Fung builds everything around.
- The book covers short, alternate-day, and extended fasts, well beyond 16:8.
- Managing hunger and breaking a fast properly are treated as skills you can learn.
- Fasting is presented as a therapeutic tool, with clear cautions on who should avoid it.
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How it fits cycle-aware fasting
The extended-fasting protocols are the book’s strength and also where women need to tread carefully. With extended fasting, ease in slowly and track your cycle, sleep, and energy as you go, pulling back if any of them change. Nothing here is organised around the menstrual cycle, so the female-specific dose is on you to add. Our overview of intermittent fasting for women sets that dose, and is intermittent fasting bad for you explains where aggressive fasting crosses from helpful to harmful.
Where it falls short
It leans heavily on the insulin and carbohydrate model, and some claims, including the degree of diabetes reversal, are debated by mainstream researchers. The protocols are sound, but a few of the promises are stated more firmly than the evidence justifies. For the same evidence weighed by an academic physician outside the low-carb frame, see our review of The Fasting Fix.
The verdict
The reference book for therapeutic fasting, and worth owning if you want to understand the how and the why in depth. Just apply the female-specific limits it does not, and involve your doctor for anything beyond a routine daily window. If the clinical tone is not what you need and consistency is your real problem, Fung’s Life in the Fasting Lane is the warmer companion.
This review is part of our roundup of the best intermittent fasting books.
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