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Why are we so fat despite our best efforts?

If you only focus on diet and exercise you're missing a huge influence—chemicals in our environment that promote weight gain.

When you think about the causes of overweight and obesity, conditions that now affect the majority of Americans, two factors likely come to mind immediately: dreadful dietary habits and lack of exercise. This is what I call the "orthodox wisdom" that we hear all the time.


But what if I said you are wrong? Well, at least not 100 percent right. You're missing a huge influence that has been driving the obesity epidemic for the last half century, and it has nothing to do with a penchant for sitting on the couch eating potato chips and watching television. It has to do with obesogens—chemicals in our environment that promote weight gain.

No one wants to be fat, but most of us are, despite working hard to eliminate unwanted pounds. Something is wrong with this narrative.

I coined the term "obesogen" in 2006 to describe chemicals that can make you fat. This sounded the alarm and spurred a flurry of scientific research studying the phenomenon of chemical-induced obesity. My team found that a chemical we were studying for other reasons had the ability to make mice fat. That started me thinking that there might be an alternative explanation for our irrepressible fatness other than calories in versus calories out.

And I was right.

Take a moment to consider obesity from a purely logical standpoint: If weight were simply determined by calories eaten minus calories burned (more formally called the energy balance equation), don't you think we would be able to more easily manage our weight? Why can we balance our bank checkbooks, but not our caloric checkbooks?

In arithmetic, one plus one equals two no matter what language you speak. But one plus one can equal more than two when it comes to the weight equation of the human body.

"Alarming" obesity levels

Epidemiological studies in humans have revealed strong links between exposure to certain environmental chemicals and greater body mass index (BMI). The BMI is a general measure that relates your weight in kilograms to your height. BMI is often used as an indicator of obesity on one end of the spectrum, and underweight on the other.

An important 2016 study showed that average BMI today is higher than it was a little more than a generation ago, even when our caloric intake and physical activity is about the same.

Put another way, adults today find it harder to maintain the same weight than did adults 20 to 30 years ago, even at the same levels of food intake and exercise.

People are about 10 percent heavier today than were people in the 1980s, even if they eat and exercise as they did back in the heydays of leg warmers and Sony Walkmans. And despite what you hear, we probably exercise more than we did in the 1980s—not less.

The time has come to reveal the untold story of obesogens with the hope that you can take better control of your waistline, your health, and especially the wellbeing of your children and future generations. After all, nowhere is the obesity epidemic more painfully disturbing to witness and acknowledge than in our young.

In January of 2016, the World Health Organization released a statement declaring that the number of obese children worldwide today is "alarming".

I will add the words "disheartening" and "unacceptable."

Beyond eating and exercise

I don't mean to minimize poor diet and physical inactivity; these remain leading causes of overweight and obesity. But we in the scientific community are increasingly finding that exposure to chemicals in our diet and environment may be an under-recognized risk factor.

In the last decade, other researchers and I have identified dozens of chemicals that can increase susceptibility to becoming obese in animals, and trigger cultured cells to become fat cells.

The narrative about our obesity epidemic, which is now a severe public health crisis, continues to be stuck in the conversation about our modern lifestyles—too much food (especially the wrong kind) and not enough exercise. When doctors address patients who are overweight, they resort to the same old questions: "How much are you eating? How often do you exercise?"

Doctors rarely ask about what their patients may be exposed to (even unwittingly) in daily life—in their food, households, workplaces, and even in medicine cabinets. Indeed, many are hostile to the idea that chemical exposures may have effects on health.

However, there are many chemicals that you are exposed to on a daily basis (many of which will surprise you) that are connected to your body weight. Losing weight is no longer only about putting down the doughnuts and hopping on a treadmill.

Obesogens contribute to obesity by disrupting the normal development and balance of fat metabolism—how your body creates and stores fat. Obesogens can reprogram stem cells in the body to develop into more fat cells. Obesogen exposure also changes how your body responds to dietary choices and handles calories.

So even though you have bought into the latest trends—Paleo, low-carb, gluten-free, high-intensity interval training—you can still struggle mightily with weight because of what is in your environment (broadly defined).

A heritable health hazard

One of the most pernicious ramifications of obesogens is that their effects can be passed on to future generations. That's right: The effects of obesogen exposure can be heritable.

The havoc that obesogens wreak on our bodies can be passed down to our biological children, grandchildren and beyond. This is why understanding the science of obesogens and knowing how to avoid them is particularly important for women who intend to become pregnant, are already pregnant, or who have young children.

The developmental years are a sensitive period in one's life, during which the body can be more vulnerable to, and affected by chemical exposures.

Our children, grandchildren and beyond deserve to have the best possible chance to live long, healthy and lean lives without being saddled with a predisposition to the burden of obesity and its related consequences.

Reducing obesogen exposure in your life is an excellent start.

Bruce Blumberg has been conducting pioneering research in endocrinology and developmental biology for more than 30 years. He is professor in the Departments of Developmental and Cell Biology, Pharmaceutical Sciences, and Biomedical Engineering at UC Irvine. He is the author of The Obesogen Effect: Why We Eat Less and Exercise More but Still Struggle to Lose Weight.

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