The Complete Guide to Fasting: Heal Your Body Through Intermittent, Alternate-Day, and Extended Fasting by Jason Fung
My rating: 2 of 5 stars
Prior to reading this book, I knew a few people who had experienced positive results with intermittent fasting, which this book covers in addition to more sustained and prolonged fasts. I was curious about the science behind it as well as the basic recommendations and protocol. I also wondered if it might be something that some of my coaching clients could benefit from.
My general feeling was that fasting, particularly shorter intermittent fasts might be a useful short-term strategy for individuals who had been overweight for long periods and/or were what I call "metabolically" sick from years of yo-yo dieting and less than ideal food choices.
Well, after reading the book, my gut feelings regarding fasting were confirmed. Fasting for short periods like twelve to sixteen hours, which essentially translates into eating only between 8 and 8 or 8 and 4, is probably a worthwhile short-term and even long term-strategy for not only losing weight but in maintaining that weight loss as it can assist with metabolic healing. In addition, it seems as if longer-term fasts (3-7 days and maybe even longer) might be a useful tool as well (at least in the short-term) for those who are obese or already have a metabolic issue like diabetes or metabolic syndrome.
That said, I am not sure this book is for everyone. I have a BS in Nutritional Sciences, a Professional Masters in Physical Therapy, and hold/have held numerous fitness certifications over the years. I've also worked with people across the lifespan with a myriad of physical and emotional issues. And in addition to my conventional professional training, I've spent over 2.5 decades taking additional continuing education courses and reading on my own. Basically, when I read this book, I read it with the benefit of a solid base from which to weigh and evaluate the claims being made.
And some of the claims in this book, while not necessarily untrue, are either misleading or confusing. He suggests that prolonged periods of fasting are not only safe but beneficial, which is a dubious claim. While it is true that in cases where someone has diabetes or is morbidly obese, the benefits of fasting may significantly outweigh risks, despite his attempts to reassure the reader to the contrary, there are risks. And yes, for the nutritionally savvy, fasting could be used to fine-tune certain systems, but for the average person??? I think the average person could take the ball and run right off the edge of a cliff. The author himself admits that with chronic fasting, in order to be effective you have to keep upping the ante. This should make one pause and take note.
So if you do read the book, read with some healthy skepticism, and if you do try more prolonged fasting (more than a day or two), make sure to discuss the benefits and risks with you personal physician.