The Obesogen Effect

CHAPTER 1

Why Are We So Fat Despite Our Best Efforts?

The Hidden Factor No One Is Talking About

If you could go back in time to an era when people believed the earth was flat, how difficult do you think it would be to convince someone that it was, in fact, round? What argument would you use to prove your point? And no, you cannot time travel with a globe in your pocket or images taken from the moon. Without any evidence of a round earth on hand, chances are you would have a tough time convincing anyone that you were right. After all, it is difficult to see the curvature of the earth from its surface—we see straight horizons, not curves. The idea of a spherical shape first appeared in Greek philosophy, credited to Pythagoras in the sixth century BCE. Aristotle provided evidence for it on empirical grounds by around 330 BCE, but it would take centuries for universal acceptance of a round earth that revolved around the sun. Even today, at least four U.S. professional basketball players claim to believe the earth is flat, so you cannot convince everyone, no matter how strong the data are!

When I speak before large professional audiences about obesogens and their impact on the obesity epidemic, I used to feel like that hapless individual trying to persuade the Flat Earth Society that the planet is indeed spherical. Old theories die hard, especially ones that people have clung to for a long time or when the reality seems to defy logic. This is absolutely true when it comes to our ideas about how and why we are so fat today. Laymen and doctors alike continue to believe that body weight is exclusively determined by the number of calories consumed compared with those burned—simple as that. Just look at the website of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), where it states definitively: “Overweight and obesity result from an energy imbalance.”⁹ If only this were the case. You might be surprised to learn that the number of health clubs has doubled over the same period that obesity has doubled. Clearly people are trying hard not to be obese. If only the solution revolved around diet and exercise alone.

Though most everyone has a clear picture of what obesity looks like, obesity is primarily defined by the body mass index (BMI). According to the WHO and American Medical Association, you are considered to be “underweight” if your BMI is less than 18.5, “normal weight” if your BMI is between 18.5 and 24.9, “overweight” if your BMI is between 25 and 29.9, and “obese” if your BMI is 30 or higher. A BMI beyond 40 is considered to be morbidly obese and indicative of a serious health problem. The BMI is a calculation based on height and weight but does not distinguish muscle from fat and bone in the body. I often show a slide comparing three people with identical BMIs of 32. One has extensive subcutaneous (below-the-skin) fat, which is not really problematic for health; another has abundant visceral fat deep inside and around the organs, which, as we will describe later, confers many of the health risks associated with obesity. The third picture is of the “Governator,” Arnold Schwarzenegger, at the pinnacle of his bodybuilding career. Despite having a BMI of 32, he was not remotely obese or even overweight. Thus, BMI is not a perfect indicator of whether or not you are obese. However, it is easy to calculate and a convenient generalization.

Let’s do one more imaginary time-travel experiment: Think about what it would be like for a family of Stone Age hunter-gatherers to experience the modern world (think The Flintstones meets My 600-lb Life). I picture stunned looks on the faces of our ancestors as they take in our modern conveniences—cars, cell phones, computers, electricity, and even supermarkets. And they are also taken aback by our body size. Given our twenty-first-century bulk, would they recognize us as members of their own species? Unlike us, they worked hard for every morsel and probably rarely had much leisure time to sit around eating unhealthy food. There were no fast-food restaurants or processed meals.

Hippocrates was right to stress the importance of moderation in diet and exercise as well as the value of food; diet was considered to be one of the most important interventions in Hippocratic medicine. This was certainly true in his time, but it misses a key part of the equation today. Hippocrates could not have known about endocrine disruptors or the effects they can have on our health and weight. And he, too, would probably be scratching his head in bewilderment at the obese masses at the dawn of the twenty-first century—a mere twenty-four hundred years after he lived.

Inexorably, we have grown accustomed to seeing a world of fat around us. The obesity facts are played over and over again in the media, so much so that they no longer surprise us. Overweight and obese individuals are the norm in most areas of the country instead of an anomaly. But fifty years ago you would have been hard-pressed to find many such people on the planet, let alone in one geographic location. As recently as 1990, obese adults in the United States comprised less than 15 percent of the population in most states. By 2010, thirty-six states had obesity rates of 25 percent or higher, and twelve of those had rates of 30 percent or higher.¹⁰ Obesity has increased threefold over the past forty years and has doubled worldwide in the last twenty years; in the last thirty years, obesity has more than doubled in children and quadrupled in teens. Today there are more overweight and obese adults aged twenty years and older in the United States (70.7 percent) than those of normal, healthy weight and underweight.^11-13 More than one-third of U.S. adults are obese, and a whopping 86 percent of us are expected to be overweight by 2020. A full 20.6 percent of adolescents aged twelve to nineteen years are obese; 17.4 percent of children aged six to eleven years are obese; and almost 10 percent of kids only two to five years old are already saddled with obesity.^11,13 Individuals who had previously enjoyed life in the slim lane at the lower end of the body mass index are now gaining weight, too, and entering the “overweight” and “obese” categories. It becomes difficult to even see the problem because when everyone around you is overweight, it turns into the expected.

But this is not normal. Could it be that we really lack the willpower to control our waistlines through classic diet and exercise because we live in an age of abundance? That it is all about lack of self-control? I don’t think so. Let’s not forget that there is also an obesity epidemic among infants of six months of age and younger, an age group where food choices and limited physical activity cannot explain this phenomenon; infants move as little or as much as they want and eat until they are full. The obesity epidemic is not limited to humans, either—it is also affecting animals living with us, including domestic dogs and cats, feral rats living in cities, and, crucially, primates and rodents living in research colonies where diets are carefully controlled.¹⁴ Are these animals also suffering from a lack of willpower? Highly doubtful.

The seminal 2016 study on our increased average BMI that I mentioned in the introduction was among the first to really call out the new facts.⁵ The researchers in this particular study mined dietary data from 36,377 U.S. adults from the National Health and Nutrition Examination Survey (NHANES) between 1971 and 2008 and showed that we are 2.3 points higher on the body mass index today than we were just a generation ago—even after correcting for how much we eat and exercise. The published conclusion spoke volumes: “Factors other than diet and physical activity may be contributing to the increase in BMI over time.” Granted, as I mentioned, BMI itself is not the best measure of obesity because it does not differentiate between fat mass and muscle mass or even where the fat is located, an important factor we will explore later. Yet despite the shortcomings of BMI as a metric, it does offer a reasonable reference point to use in evaluating body composition in the population.

So what is the most compelling explanation for these new facts? Something has changed in our environment—something that occurs where humans live, work, and eat.

HOW EXPOSED ARE YOU?

Take a look around you and think about a typical day, including that of your young children if you have them. In what ways can your environment impact your biology—and especially that of your children who are still developing, which makes them uniquely vulnerable? Here is a brief quiz that can help clue you in to the kinds of exposures that can cause a human body to create more fat. Many of these exposures could have happened long ago.

Don’t panic if you answered “yes” to any of these questions. Knowledge is power, and I will equip you with the information you need to take better charge of your waistline and health. In this chapter, we will take a tour of the obesity epidemic so you have a solid foundation to understand what I am calling “the new science of fat.” It will help you begin to see why some people gain weight faster and lose it more slowly than others, irrespective of diet and exercise.

THEN AND NOW: THE MYSTERY OF OUR MODERN SCOURGE

The image below shows two different individuals.

Back in our hunter-gatherer days more than ten thousand years ago, when we had to forage for our food by collecting wild plants, fishing, and pursuing wild animals, most of us resembled the individual on the left. Modern hunter-gatherers in Africa and elsewhere who continue to live this way still look like the woman on the left. However, many of us come closer to looking like the person on the right.

Some would argue that one of the reasons it is so easy to turn into the person on the right is that we evolved when food was much harder to find. We were programmed for survival in a world where food was scarce and periods of famine were frequent. But today we live in a calorie-rich environment 365 days a year. Food is abundant, and unhealthy foods tend to be the most affordable, available options. Many of these unhealthy foods are engineered to act on our brain’s pleasure centers to keep us addicted and coming back for more, similar to how drug addicts on heroin or crack cannot easily quit.¹⁵ While the theories around whether obesity-causing genes are widespread, or whether there is an obesity-favoring metabolic program, the idea that we have been molded by evolution to use calories sparingly makes some sense and is worth considering.

The “thrifty gene” hypothesis suggests that the two images here reflect an obvious mismatch between our Stone Age genes and space age circumstances. Having access to ample calories allowed the body to build fat stores quickly when food was available so it could endure long stretches of food shortages, which were inevitable and common throughout much of human evolution. Perhaps we retain essential components of this hunter-gatherer genome—after all, a small percentage of each of our genomes is derived from our Neanderthal and Denisovan cousins.¹⁶ These genes helped us store fat during times of abundance so that this fat could be used during those regular periods of scarcity, and thus they lead to energy being spent sparingly. The end of famine in developed countries means that accumulated changes in genes that were once favorable for storing fat instead could cause widespread obesity. In other words, “famine genes” that were once advantageous for survival became liabilities that could threaten health and longevity in the land of plenty.

Geneticist James Neel first described the “thrifty gene” hypothesis in 1962 to help explain why diabetes has such a strong genetic basis yet results in such negative effects.¹⁷ According to the theory, the genes that predispose someone to diabetes—the “thrifty genes”—were advantageous long ago. But once modern society changed and we developed agriculture, our access to food changed, too. Our bodies no longer needed those thrifty genes, but they were still active. Today they continue to prepare us for a famine that will not arrive. Our thrifty genes are partially responsible for the obesity epidemic, which is closely tied to the development of diabetes.

If there are such things as “thrifty genes,” then it must be possible to identify them with the advent of modern, affordable DNA-sequencing methods. This is where the thrifty gene hypothesis has run into some critics. If these thrifty genes have been around for the two hundred thousand years or so that we Homo sapiens have existed, and agriculture began only around twelve thousand years ago, then pretty much everyone should carry the majority of the thrifty genes that have ever existed. Dr. John Speakman, a prominent challenger of the thrifty gene hypothesis, showed in a 2016 paper that none of the common obesity-related genes that had been identified conferred any properties or traits that could be considered to have provided an adaptive advantage.¹⁸ On the other hand, perhaps there are bona fide thrifty genes that have yet to be identified, so the case is not yet closed. As we will discuss in chapter 5, it is clear that there is a “thrifty phenotype.” That is, in both human and animal studies, it is possible to identify individuals that store more of the calories they consume as fat, whereas others burn more calories or eliminate more in their feces. If thrifty genes are not responsible, then what is?