"The Complete Guide to Fasting" - A Book Review
Posted November 22, 2022 by Matthew Romans
Jason Fung, MD, is a graduate of the University of Toronto medical school and he completed a fellowship in nephrology at UCLA. Dr. Fung runs the Intensive Dietary Management Program in Toronto, where he works with patients suffering from obesity, insulin resistance, and diabetes. Jimmy Moore is a blogger, author, and host of several low-carb podcasts who achieved a stunning 180 pound weight loss due to a combination of dietary change, exercise, and fasting. These two gentlemen teamed up in 2016 to write "The Complete Guide to Fasting." I was recently asked by a client if I had any book recommendations on intermittent fasting. I had read many articles on the subject and learned about the concept as part of several medical and nutritionally-themed books, but had not come across a book specifically dedicated to fasting. A quick search on Amazon brought me to this title, so I went ahead and purchased the book.
Fasting, very simply, is what happens when we are not eating. Much of what passes for modern dietary advice is flat-out wrong, and over the last 50 years or so we have been conditioned to believe that eating smaller meals spread out throughout the day is the healthy way to go. Nothing could be further from the truth. Fasting is something that has been around for thousands of years, and it has its place in many cultures and religions all over the world. Dr. Fung gives a very concise explanation of what happens when we fast. He says, "Insulin levels drop, signaling the body to start burning stored energy. Glycogen (the glucose that's stored in the liver) is the most easily accessible energy source, and the liver stores enough to provide energy for twenty-four hours or so. After that, the body starts to break down stored fat for energy." So the idea is that we want to tap into our reserves of body fat to use as our primary energy source, which can only happen efficiently when we are in a fasted state. Insulin is the key hormone; its purpose is to help nutrients get into our cells. Lower insulin levels mean you are maintaining insulin sensitivity, which is a good thing. Higher insulin levels can be dangerous to your health, and are often associated with heart disease, stroke, obstructive sleep apnea, cancer, Alzheimer's disease, and many other diseases of modern civilization. Chronic high insulin can also lead to Type 2 diabetes. Fasting forces your body to use fat as its primary fuel source. If you temporarily deprive yourself of food, the body will use the resources it already has.
What are the benefits of fasting? I believe there are some psychological improvements that can be achieved through fasting (especially a feeling of accomplishment after an extended fast), but Dr. Fung discusses six key physical improvements that can be obtained through regular fasting.
Stimulate growth hormone. This is key for tissue repair, as well as building and maintenance of lean muscle mass.
Regulate insulin, other hormones, and blood sugar. Energy levels will be kept relatively stable, thus avoiding peaks and valleys at various times throughout the day
Apoptosis, or programmed cell death. This is a normal part of an organism's growth and development, and can help you avoid certain types of cancers.
Autophagy. Similar in nature to apoptosis, but this is a regular form of cellular cleansing that can only occur when you are in a fasted state.
Increased alertness. Think about what happens after a large meal (certainly topical, with Thanksgiving just around the corner). We've all heard the term "food coma", but you're usually groggy, and it's not only because of the tryptophan. Being in a fasted state means that blood is not concentrated in your gut, helping you to digest a large meal. You feel more awake, and your thinking is more clear when you fast.
Lowers cholesterol. Cholesterol, in and of itself is not a bad thing, since every cell membrane in your body contains this substance. According to Dr. Fung, "...Since excess carbohydrates are converted to triglycerides, the absence of carbohydrates means fewer triglycerides. Remember that triglycerides are released from the liver as VLDL (very low density lipoprotein), which is the precursor of LDL (low density lipoprotein). Therefore, reduced VLDL eventually results in lowered LDL."
One particularly interesting chapter of the book deals with some of the myths about fasting. Here, Dr. Fung does a wonderful job of exploding these myths, and hopefully this educates people who have been misinformed. One commonly expressed reservation that people have about fasting is that they think it will cause them to burn muscle. As the author explains, "Muscle, on the other hand, is preserved until body fat becomes so low that the body has no choice but to turn to muscle. This will only happen when body fat is at less than 4 percent. (For comparison, elite male marathon runners carry approximately 8 percent body fat and female marathoners slightly more.)" Most of us carry around more body fat than that, so the risk of losing muscle is practically nonexistent. Another myth that has become accepted as fact is that fasting causes low blood sugar. Not true. According to Dr. Fung, "If you fast for longer than twenty-four to thirty-six hours, glycogen stores become depleted. The liver now can manufacture new glucose in a process called gluconeogenesis, using the glycerol that's a by-product of the breakdown of fat. This means that we do not need to eat glucose for our blood glucose levels to remain normal." The popular version of what we have been told about fasting, from both the mainstream media and establishment medicine is wildly inaccurate.
How should you go about fasting? My personal recommendation is to start by fasting for 12 hours per day, and gradually work up to 16 hours per day, with an eight hour feeding window (the time between your first and last meals of the day). Each individual is different, and the great thing about fasting is that you can customize how you do it in order to best suit your lifestyle. You can avoid fasting during the holidays or if you have a wedding to attend (or any social event that involves food), and then get right back on track afterward. Dr. Fung details some of the programs that he uses with his patients, and he often utilizes 24 hour, 36 hour, or even longer fasts. Co-author Moore devotes an entire chapter to his personal experiences with fasting and the ways that he experimented and experienced great success. If you're doing an extended fast, it's a good idea to consume plenty of water and a multivitamin, to avoid becoming nutrient deficient. Drinking bone broth is also a good strategy. Fasting is safe and effective for the vast majority of the population, but should be avoided if you are pregnant, breastfeeding, under the age of 18, or severely malnourished. The last point I'll make is that fasting is most easily accomplished if you are on a ketogenic diet, or eat a diet consisting largely of single-ingredient whole foods, with plenty of saturated fat. This will make you less prone to hunger.
Dr. Fung writes well, and the insights provided by Mr. Moore adds a nice touch to the book. The concepts are fairly simple to understand and listed in a way that makes for easy reference if you are a health professional. However, this book is not written for the professional; it's written for the layperson that wants to make a significant change to their health. There are even helpful recipes located in the back of the book, as well as some sample fasting schedules that can be adopted.
Fasting, in and of itself, is very simple (but not necessarily easy) to do. Encouragement from friends and family members will go a long way toward success. It doesn't require money or a product, all it entails is not eating for designated periods of time. I highly recommend incorporating intermittent fasting along with your regular Total Results workouts in order to facilitate fat loss and maximize metabolic effect. It will cost you nothing and will give you a huge return on your exercise investment.