The Obesity Code eats most other weight loss books for lunch, without gaining an ounce.
When Dr. Jason Fung asked me to review his new book, The Obesity Code: Unlocking the Secrets of Weight Loss, I eagerly agreed, and I’m delighted to say that his book truly exceeded my expectations.
Dr. Fung argues that obesity is not about calories or fat grams or exercise, but about hormones. The main character in his book is insulin, a powerful hormone that regulates our metabolism. When insulin levels run too high for too long, we develop “insulin resistance,” which can make us fat. By identifying the true culprits in obesity, Dr. Fung provides readers with much-needed hope and strategies grounded in science rather than mythology.
Dr. Fung is a nephrologist (kidney specialist) practicing in Toronto, where he founded the Intensive Dietary Management program. His signature prescription for patients with obesity and type 2 diabetes is his intermittent fasting protocol. Dr. Fung is considered one of the leading specialists in intermittent fasting, a topic I knew little about prior to reading his book.
Even if you have absolutely no interest in fasting, you’ll learn all kinds of wonderful things that will completely change the way you think about food and weight. You will emerge armed with powerful information about your health that you can use to improve almost any diet and help you reach your health or weight loss goals. Dr. Fung has chosen to focus squarely on obesity, but the story he tells of how food can damage our delicately balanced hormonal networks has implications for all of us, no matter how much we weigh. This is because insulin resistance is about so much more than obesity and diabetes—insulin resistance is nothing less than the driving force behind most “diseases of civilization,” from heart disease to cancer to Alzheimer’s disease. Therefore, even if your weight is normal, you can still have insulin resistance, putting you at risk for serious health problems down the road. If you fall into any of the below categories, this book is for you:
- Do you gain weight easily?
- Do you gain weight even though you exercise religiously and don’t overeat?
- Do you have trouble losing weight, even on a low-carbohydrate diet?
- Do you want to prevent or reverse pre-diabetes or type 2 diabetes?
- Are you curious about fasting as a weight loss strategy?
- Do you have an insulin-resistant condition, such as pre-diabetes, fatty liver, polycystic ovarian syndrome (PCOS), "high cholesterol," pre-Alzheimer's, or erectile dysfunction?
- Are you a health professional who needs to understand how to help people lose weight?
- Do you want to know which foods are most damaging to your metabolism and overall health?
Obesity is a hormonal problem
For decades we were (mis)taught that low-fat, low-calorie diets, in combination with exercise, are the key to maintaining a healthy weight. Yet, the tired, impotent mantra of “eat less, exercise more” has betrayed countless overweight people. How many people do you know who have worked hard their whole lives to control their weight without any lasting success? On the other hand, we all know people who maintain a healthy weight without having to count a single calorie or ever get up off the couch. Overweight people are hormonally different.
Dr. Fung's writing style strikes just the right balance, providing enough rock solid research to convince even the most skeptical physician of his argument, without overwhelming or boring a general audience. He takes readers by the hand, leads them out of the confusion about dieting and weight loss, and into the light: obesity is a hormonal disorder of persistently high insulin levels and insulin resistance, caused by eating the wrong foods too often. If your insulin levels are too high, no matter what diet you are following, and no matter how much you exercise, you will gain weight.
I have read a great deal about the relationship between insulin and obesity, so I was pleasantly surprised to see that Dr. Fung tells the insulin story in a uniquely compelling and convincing way. He assembles a firing squad of fascinating facts from history, medicine, politics, science, and human experience, takes aim at all the useless myths about weight control, and unceremoniously shoots each of them dead, one by one, right before your very eyes. Even though the insulin-obesity connection is one I already understood very well, he explains it so beautifully and from so many different angles, that I was riveted.
For the throngs of people who haven’t yet been introduced to these ideas, this book will be nothing short of a miraculous revelation. Dr. Fung provides people who have been struggling with weight their whole lives with precious “Aha!” moments that will finally relieve them of the guilt, shame, and demoralization that can come with failed attempts at weight loss, and empower them with the information they need to succeed.
Dr. Fung explains exactly why losing weight is so hard for overweight people. He addresses all of the following questions, and more:
- Why does metabolism slow down as we get older?
- Why does the body resist weight loss?
- What drives yo-yo dieting and the weight roller coaster?
- Why doesn’t exercise work as well as we think it should?
- Why are children and even babies now becoming fat and diabetic?
- How does stress contribute to weight gain?
- Are some carbohydrates more dangerous than others?
- Does it matter how much food you eat in one sitting?
- Can eating too much protein interfere with weight loss?
- Are all calories created equal?
- How can low-calorie sweeteners make it harder to lose weight?
- Is breakfast really the most important meal of the day?
- Why doesn’t fat make you fat?
The obesity solution
How can you correct your hormonal imbalance? Dr. Fung believes that you must dramatically change not only what you eat, but when you eat.
The fastest way to dramatically lower your insulin levels is to simply stop eating. This is why the cornerstone of Dr. Fung’s approach is to fast several times per week. He educates and reassures readers about his approach: he writes about fasting traditions in human history, how fasting affects hormones, how to cope with potential side effects, and (curiously) what you can eat and drink during your fast.
What should you eat when you’re not fasting?
Unlike many other low-carbohydrate advocates, Dr. Fung emphasizes the importance of eating real, whole foods. In this way, he demonstrates that he cares not only about your weight, but also about your overall health.
While there are no recipes or menus in the book, he does provide a couple of sample weekly meal plans to give you an idea of what his approach looks like. He doesn’t prescribe a particular number of calories, carbohydrate grams, or protein grams; instead, he sets forth five basic principles to guide your food choices. This means that you can apply his philosophy to most diet plans, from plant-based to Paleo. He provides a great deal of information about specific foods and how they affect your metabolism, including surprising tidbits about fiber, vinegar, and dairy products, just to name a few.
I agree wholeheartedly with the lion's share of the ideas within this book, and thus my criticisms are minor.
The diet he proposes is extremely healthy compared to the average diet, but his sample menus do include whole grains, legumes and dairy products. Although he emphasizes that his menus are only suggestions and can be modified, I was surprised to see dairy products on the table, as dairy products have powerful effects on our metabolic hormones. Dr. Fung sends a somewhat mixed message about dairy. He warns people against consuming whey protein, because it triggers insulin spikes, yet encourages the consumption of full-fat dairy products, citing primarily epidemiological studies to support this recommendation. [Yet, he does a beautiful job in his chapter entitled "fat phobia" of calling out epidemiological studies as dangerously misleading.] As most of you know, I put virtually no stock in nutritional epidemiology, and I believe that grains and legumes pose health risks for humans. Therefore, I would simply recommend that people who choose to follow his dietary protocol avoid grains, legumes, and dairy products.
I have never tried intermittent fasting myself, so I can’t comment on what it’s like or how it compares to my own strategy, which is a high-fat, adequate protein, very low-carbohydrate ketogenic diet. A ketogenic diet is also very effective at lowering insulin levels, and does a beautiful job of reducing appetite. For people trying to understand which of these approaches is right for them, I wish that Dr. Fung had shared his thoughts on how these two plans compare, particularly when it comes to questions of metabolic adaptation, hunger, and stress hormone levels.
Dr. Fung emphasizes that the stress hormone cortisol causes weight gain. I wish that he had addressed the question of whether fasting triggers an increase in cortisol levels, which is a common concern in the blogosphere. I also would have loved some case examples from his practice showing us how his patients respond to intermittent fasting—insulin, cortisol, blood glucose, appetite, and weight trends over time would all be fascinating parameters to observe.
I also wish he had shared with us his perspective on the question of why women tend to gain weight more easily than men, since this would seem to be another phenomenon signifying that obesity is a hormonal disorder.
Lastly, Dr. Fung makes the case that fructose is worse than glucose when it comes to the development of insulin resistance, but in my deep exploration of this topic in a series about fructose I wrote last summer ["Has Fructose Been Framed?"], I was unable to find evidence of this except in studies of pure fructose (which doesn’t exist in nature) at extremely high doses. [The clinical experiment he referenced in his fructose chapter used 1,000 calories per day of pure fructose, and therefore lies within this exceptional category.]
In my view, insulin resistance is Public Health Enemy #1, and The Obesity Code is the most complete and most satisfying book about insulin resistance I have ever read. I am so glad to finally have a physician-authored, science-rich, accessible source to recommend to my colleagues, friends, family, and patients that explains so clearly what we all need to know about this massively important topic. Go ye forth, read, and be . . . ahem . . . enlightened.