The Obesity Code: Unlocking the Secrets of Weight Loss

“There is no survival advantage to carrying a very high body-fat percentage.”

Fung debunks several weight loss myths. In this quote, he addresses the popular misconception that the body evolved to put on weight to survive. The contrary is true–humans evolved toward leanness.

“It. Just. Does. Not. Work.”

This punctuated quote addresses caloric reduction, the most common weight loss method. The research shows that eating less only results in short-term, not lasting, weight loss.

“If we want to reduce obesity, we need to focus on what makes us obese.”

Researchers have long known that exercise does not result in lasting weight loss, yet they continue to spend time, funding, and energy on the topic, leaving few resources to understand and fight obesity and causing dieters to blame themselves for failing to lose weight.

“The reason diets are so hard and often unsuccessful is that we are constantly fighting our own body.”

This quote addresses homeostasis, or the body’s tendency toward equilibrium. Caloric reduction is a self-defeating weight loss strategy because the body will activate hormones to return to its original set weight.

“The caloric reduction theory of obesity was as useful as a half-built bridge.”

Fung makes ample use of analogies throughout his book. This rhetorical strategy keeps readers engaged and helps explain scientific concepts to non-specialists.

“A recent study suggests that 75% of the weight-loss response in obesity is predicted by insulin levels. Not willpower. Not caloric intake. Not peer support or peer pressure. Not exercise. Just insulin.”

This passage underscores Fung’s primary thesis, namely, that high, persistent insulin causes obesity, not excess calories, environmental factors, or the lack of exercise. People fail to lose weight using conventional means because the approaches are flawed.

“I can make you fat.

With this provocative statement, Fung expresses certainty in his hormonal theory of obesity. Administering prednisone, the synthetic version of cortisol, leads to weight gain because cortisol is central to carbohydrate metabolism, just like insulin.

“Doctors played their favorite game: blame the patient.”

For decades, the medical community failed to reassess failing weight loss methods. Instead of seeking more effective treatments, they blamed patients for being obese.

“Obesity at age seventeen has consequences that reach decades into the future.”

This quote stresses that obesity is a time-dependent disease that develops over decades. Obese children are likely to become obese adults. In turn, obese adults tend to have obese children. Long-standing obesity is difficult to treat because the body develops insulin resistance overtime.

“Many health professionals endorse the use of artificial meal-replacement shakes or bars, drugs and surgery as evidence-based diet aids.”

Fung emphasizes the complicity of healthcare professionals in promoting the interests of large corporations. Food and drug companies develop nutritionally dubious foods, medications, and surgical procedures to make money. These products do little to support weight loss.

“Socioeconomic status has long been known to play a role in the development of obesity in that poverty correlates very closely with obesity.”

Fung debunks common misconceptions about poverty and obesity, persuasively arguing that poor people tend to be obese because they eat affordable, refine carbohydrates, rather than more expensive whole foods.

“During the years 1977 to 2000, the prevalence of childhood obesity skyrocketed in every age category.”

The dramatic increase in childhood obesity in the closing decades of the 20th century has had lasting effects, as obese children tend to become obese adults. Fetal exposure to high levels of insulin helps explain the rise in childhood obesity. This dramatic increase in obesity was largely fueled by the rising popularity of snack foods and fast food, which had been a minor part of the American diet until that time. The change also reflects the pervasive emphasis on low-fat diets as the best way to lose weight.

“Sugar is fattening.”

Scientists almost universally agree that sugar is fattening, but for decades, health authorities promoted the low-fat diet to combat obesity. The American public cut back on fat rather than sugary drinks and foods, which fueled the obesity epidemic.

“Diet drinks contain very few calories and no sugar.”

Fung addresses the popular misconception that only excess calories and sugar drive weight gain. Diet soda is high in artificial sweeteners, which lead to insulin spikes and weight gain, despite their low caloric content.

“Controversy surrounds the humble carbohydrate. Is it good or bad?”

One of the most valuable contributions of Fung’s book is that it helps readers understand contradictory health recommendations. Health professionals paid relatively little attention to the role of carbohydrates in weight gain until the 1990s, instead pointing the finger at fats. Although many people now recognize the relationship between carbs and obesity, confusion regarding different types of carbs continues. Not all carbs are equal: Fung recommends avoiding refined carbs because they cause the biggest spikes in insulin and instead choosing unprocessed grains and ancient grains, like quinoa.

“Today’s wheat is simply not as nutritious as in previous generations.”

Fung addresses the relationship between technological advances and obesity. Processed foods are more common today than at any other point in history. Moreover, processing methods have changed in ways that promote obesity. For example, the modern flourmill, which replaced stone grinding, strips flour of bran, germs, oils, vitamins, fibers, fats, and proteins. This finely processes flour is quickly and easily absorbed in the stomach, amplifying the insulin effect.

“Carbohydrates are just long chains of sugars.”

Fung uses direct and simple language throughout his book. Avoiding scientific jargon broadens his readership, making potentially challenging material accessible to a wide range of readers. This passage also emphasizes that even though a carbohydrate-rich food, such as bread, is not sweet, it acts as sugar in the body.

“We generally discard most of the organ meats, cartilage and bones—which is analogous to drinking the juice of a fruit but discarding the pulp.”

Fung makes ample use of analogies throughout his book. This analogy stresses the importance of eating whole foods. Eating animal muscle while discarding organs, cartilage, and bones, privileges protein over other key nutrients.

“The seemingly strong link between heart disease and saturated fat consumption was forged with quotation and repetition, not with scientifically sound evidence.”

This quote debunks yet another pervasive food myth, namely, that dietary fat causes weight gain. This misconception gained traction in 1970, with the publication of a study comparing coronary disease across seven nations. Fung points out that though the study found correlations between dietary fat and heart disease, it did not establish causation.

“To replace butter, Americans increasingly reached for that tub of edible plastic: margarine.”

By comparing margarine to plastic, Fung draws attention to the deleterious effects of processed foods on health and the way dietary advice has changed over time: What was once considered a healthy alternative to butter has proven to be a chemically altered substance that impedes rather than promotes weight loss. This quote also alludes to the role of natural fats in maintaining a healthy weight.

“All diets work […]. All diets fail.”

One of Fung’s central points in The Obesity Code is that conventional diets do not yield long-term results. The Mediterranean Diet, the Atkins Diet, and even the low-fat, low-calorie diet all produce weight loss in the short term (though they differ in the amount of weight lost). However, weight loss plateaus at the six-to-twelve-month mark. A period of regain follows, despite continued dietary compliance.

“The truth is that there are multiple overlapping pathways that lead to obesity.”

Obesity is a multifactorial disease that requires multiple targets and treatments. One major contributor is the hormonal imbalance hyperinsulinemia that runs as a through line across patients. Sugar is a problem for some people while others suffer from insulin resistance. A low-carb diet might work for the former while the latter might benefit from intermittent fasting or changing their mealtimes. Controlling cortisol levels with stress reduction and better sleep are also key factors for some patients.

“Long-term dieting is futile.”

Homeostasis dooms all diets. The body reacts to weight loss by activating hormonal processes that lead to weight gain. Achieving long-term weight loss requires cutting back on foods that raise insulin levels and combatting insulin resistance with fasting.