The Obesity Code. Jason Fung

for which the only correct treatment is progressively increasing insulin dosages. He argues, instead, that type 2 diabetes is a disease of insulin resistance with excessive insulin secretion—in contrast to type 1 diabetes, a condition of true insulin lack. To treat both conditions the same way—by injecting insulin—makes no sense. Why treat a condition of insulin excess with yet more insulin, he asks? That is the equivalent of prescribing alcohol for the treatment of alcoholism.

      Dr. Fung’s novel contribution is his insight that treatment in type 2 diabetes focuses on the symptom of the disease—an elevated blood glucose concentration—rather than its root cause, insulin resistance. And the initial treatment for insulin resistance is to limit carbohydrate intake. Understanding this simple biology explains why this disease may be reversible in some cases—and, conversely, why the modern treatment of type 2 diabetes, which does not limit carbohydrate intake, worsens the outcome.

      But how did Dr. Fung arrive at these outrageous conclusions? And how did they lead to his authorship of this book?

      In addition to his realization, described above, of the long-term nature of disease and the illogic of treating a disease’s symptoms rather than removing its cause, he also, almost by chance, in the early 2000s, became aware of the growing literature on the benefits of low-carbohydrate diets in those with obesity and other conditions of insulin resistance. Taught to believe that a carbohydrate-restricted, high-fat diet kills, he was shocked to discover the opposite: this dietary choice produces a range of highly beneficial metabolic outcomes, especially in those with the worst insulin resistance.

      And finally came the cherry on the top—a legion of hidden studies showing that for the reduction of body weight in those with obesity (and insulin resistance), this high-fat diet is at least as effective, and usually much more so, than other more conventional diets.

      Eventually, he could bear it no longer. If everyone knows (but won’t admit) that the low-fat calorie-restricted diet is utterly ineffective in controlling body weight or in treating obesity, surely it is time to tell the truth: the best hope for treating and preventing obesity, a disease of insulin resistance and excessive insulin production, must surely be the same low-carbohydrate, high-fat diet used for the management of the ultimate disease of insulin resistance, type 2 diabetes. And so this book was born.

      In The Obesity Code, Dr. Fung has produced perhaps the most important popular book yet published on this topic of obesity.

      Its strengths are that it is based on an irrefutable biology, the evidence for which is carefully presented; and it is written with the ease and confidence of a master communicator in an accessible, well-reasoned sequence so that its consecutive chapters systematically develop, layer by layer, an evidence-based biological model of obesity that makes complete sense in its logical simplicity. It includes just enough science to convince the skeptical scientist, but not so much that it confuses those without a background in biology. This feat in itself is a stunning achievement that few science writers ever accomplish.

      By the end of the book, the careful reader will understand exactly the causes of the obesity epidemic, why our attempts to prevent both the obesity and diabetes epidemics were bound to fail, and what, more importantly, are the simple steps that those with a weight problem need to take to reverse their obesity.

      The solution needed is that which Dr. Fung has now provided: “Obesity is . . . a multifactorial disease. What we need is a framework, a structure, a coherent theory to understand how all its factors fit together. Too often, our current model of obesity assumes that there is only one single true cause, and that all others are pretenders to the throne. Endless debates ensue . . . They are all partially correct.”

      In providing one such coherent framework that can account for most of what we currently know about the real causes of obesity, Dr. Fung has provided much, much more.

      He has provided a blueprint for the reversal of the greatest medical epidemics facing modern society—epidemics that he shows are entirely preventable and potentially reversible, but only if we truly understand their biological causes—not just their symptoms.

      The truth he expresses will one day be acknowledged as self-evident.

      The sooner that day dawns, the better for us all.

      TIMOTHY NOAKES OMS, MBchB, MD, DSC, PhD (hc), FACSM, (hon) FFSEM (UK), (hon) FSEM (Ire)

      Emeritus Professor

      University of Cape Town, Cape Town, South Africa

INTRODUCTION

      THE ART OF medicine is quite peculiar. Once in a while, medical treatments become established that don’t really work. Through sheer inertia, these treatments get handed down from one generation of doctors to the next and survive for a surprisingly long time, despite their lack of effectiveness. Consider the medicinal use of leeches (bleeding) or, say, routine tonsillectomy.

      Unfortunately, the treatment of obesity is also one such example. Obesity is defined in terms of a person’s body mass index, calculated as a person’s weight in kilograms divided by the square of their height in meters. A body mass index greater than 30 is defined as obese. For more than thirty years, doctors have recommended a low-fat, calorie-reduced diet as the treatment of choice for obesity. Yet the obesity epidemic accelerates. From 1985 to 2011, the prevalence of obesity in Canada tripled, from 6 percent to 18 percent.¹ This phenomenon is not unique to North America, but involves most of the nations of the world.

      Virtually every person who has used caloric reduction for weight loss has failed. And, really, who hasn’t tried it? By every objective measure, this treatment is completely and utterly ineffective. Yet it remains the treatment of choice, defended vigorously by nutritional authorities.

      As a nephrologist, I specialize in kidney disease, the most common cause of which is type 2 diabetes with its associated obesity. I’ve often watched patients start insulin treatment for their diabetes, knowing that most will gain weight. Patients are rightly concerned. “Doctor,” they say, “you’ve always told me to lose weight. But the insulin you gave me makes me gain so much weight. How is this helpful?” For a long time, I didn’t have a good answer for them.

      That nagging unease grew. Like many doctors, I believed that weight gain was a caloric imbalance—eating too much and moving too little. But if that were so, why did the medication I prescribed—insulin—cause such relentless weight gain?

      Everybody, health professionals and patients alike, understood that the root cause of type 2 diabetes lay in weight gain. There were rare cases of highly motivated patients who had lost significant amounts of weight. Their type 2 diabetes would also reverse course. Logically, since weight was the underlying problem, it deserved significant attention. Still, it seemed that the health profession was not even the least bit interested in treating it. I was guilty as charged. Despite having worked for more than twenty years in medicine, I found that my own nutritional knowledge was rudimentary, at best.

      Treatment of this terrible disease—obesity—was left to large corporations like Weight Watchers, as well as various hucksters and charlatans mostly interested in peddling the latest weight-loss “miracle.” Doctors were not even remotely interested in nutrition. Instead, the medical profession seemed obsessed with finding and prescribing the next new drug:

      •You have type 2 diabetes? Here, let me give you a pill.

      •You have high blood pressure? Here, let me give you a pill.

      •You have high cholesterol? Here, let me give you a pill.

      •You have kidney disease? Here, let me give you a pill.

      But all along, we needed to treat obesity. We were trying to treat the problems caused by obesity rather than obesity itself. In trying to understand the underlying cause of obesity, I eventually established the Intensive Dietary Management Clinic in Toronto, Canada.

      The conventional view of obesity as a caloric imbalance did not make sense. Caloric reduction had