Review of The Obesity Code – Shedding New Light on What Drives Weight Gain and Loss

By Lisa Newman, Publisher

The Obesity Code: Unlocking the Secrets of Weight Loss (Why Your Body’s Own Insulin Is the Key to Controlling Your Weight), by Jason Fung, MD (Greystone Books, 2016).

In The Obesity Code, Canadian kidney specialist Jason Fung sets out to disprove several popular ideas about weight. In the book he asserts:

  • The calorie model of weight (that is, energy in minus energy out) is wrong.
  • Carbohydrate intake does not drive weight gain.
  • The popular advice to eat more frequently is misguided.

Dr. Fung then seeks to prove his central thesis that weight is driven by hormones, asserting:

  • Insulin is the major hormone determining our weight.
  • Insulin resistance, rather than insulin itself, is the primary driver of weight gain.

The book is thorough and well-researched, although somewhat repetitive. It’s structured logically, starting with the epidemic of weight gain. It then moves to the reasons behind weight gain, the arguments supporting the author’s premise, and finally, his proposed solution. I like that he often presents the counter arguments so we can review both sides of an issue.

Dr. Fung writes in a casual style punctuated with analogies that make it easy for the nonprofessional to grasp his points, such as this one:

“Consider the money that you earn in a year (Money In) and the money that you spend (Money Out). Suppose you normally earn and also spend $100,000 per year. If Money In is now reduced to $25,000 per year, what would happen to Money Out? Would you continue to spend $100,000 per year? Probably you’re not so stupid, as you’d quickly become bankrupt…

Let’s apply this reasoning to obesity. Reducing Calories In works only if Calories Out remains stable. What we find instead is that a sudden reduction of Calories In causes a similar reduction in Calories Out, and no weight is lost as the body balances its energy budget…”

It would be difficult to read this book and not gain a clear understanding of why traditional weight-loss diets don’t work. Anyone who has a history of dieting will relate to his statement: “The reason diets are so hard and often unsuccessful is we are constantly fighting our own body.” Dr. Fung emphasizes that “eating more and moving less does not cause obesity, but is instead the result of obesity.”

Many readers will no doubt find it surprising that Dr. Fung does not see carbohydrate intake as a problem. He points out that the effect of a low-carb diet evaporates after one year, with much of the weight regained. “The notion that carbohydrates are the only driver of insulin is incorrect,” he states. Additionally, he says you can’t lump all carbs into one category as they have differing effects on the body.

Arguments against eating a single food, or even a single food group, are too simplistic to explain the complexity of fat in humans, according to Dr. Fung. He explains that this is one reason why dividing food into categories of “bad” and “good” doesn’t work.

Additionally, while Dr. Fung is focused on insulin resistance, he notes throughout the book that obesity is multifactorial. In several places, he explains that the reason you aren’t able to lose weight may have little to do with your eating. Instead, he suggests, you may need to look at other factors, such as stress or sleep.

Dr. Fung’s description of the difference between measuring blood glucose vs. blood insulin is informative. He explains that protein has a surprising and substantial response on the insulin index, whereas it doesn’t affect blood glucose.

Based on this and other evidence, Dr. Fung makes the astonishing assertion that “insulin can increase independently of blood sugar.” And that this could be why high-protein diets have failed in their weight-loss promise.

Dietary fat, he asserts, has the weakest effect on insulin, and pure fat does not stimulate insulin at all. This finding is the basis for his controversial use of high-fat diets to counter Type 2 diabetes.

Dr. Fung’s nutritional recommendations are surprisingly balanced and essentially the same as most nutritional experts: Eat less sugar and reduce the intake of processed food. In contrast to current trendy diets, he has no problem with dairy (recommending full fat), nuts, eggs, coffee, and unprocessed carbohydrates. He also takes a moderate approach to saving some foods for special occasions, rather than attempting to eliminate any category of food.

It’s when you eat, rather than what you eat, that can make the biggest difference in weight loss, Dr. Fung asserts. He recommends an eating rhythm that allows for periods without food.

This can be achieved by simply not eating between meals; by implementing periods of “intermittent fasting,” where meal times are stretched further apart (typically by eating dinner earlier and breakfast later or not at all); or by abstaining from food for one or more days.

A complaint I have with Dr. Fung is that his use of snacking as a description for frequent or continuous food intake is incomplete and confusing. What he is describing in most instances is more correctly known as “grazing”—a term that refers to mindless food intake throughout the day.

Grazing is a form of emotional eating that can be detrimental to health and weight. A snack, on the other hand, generally means a conscious instance of eating meant to keep you from becoming overly hungry between meals. Used this way, snacks can go a long way to reducing overeating and binging in the evening.

I find the general lack of discussion of emotional eating to be the biggest absence in this book. There is no doubt that restriction of meals can trigger emotional eating, and thus undermine any weight loss or health advantage.

Another significant weakness is that intermittent fasting appears to work for weight loss by decreasing calories taken in. If the calorie model doesn’t work, then weight loss from reduced calories could also prove to be a mirage. However, I commend him on his advice that fasting and restrictive diets, like the high fat one he uses for diabetes, should be undertaken only when medically monitored.

Overall, The Obesity Code is worth your time, especially if you have blood-sugar concerns. But it remains to be seen if Dr. Fung’s argument for intermittent fasting will fulfill its promise for sustainable weight loss.

If you want to read more about Dr. Fung and his theories, check out his other books, including his newest The Diabetes Code: Prevent and Reverse Type 2 Diabetes Naturally or follow him on Medium where he is a frequent contributor.