It's hard to escape the image of Americans as slothful and overweight. But what if being fat weren't totally our fault?
The narrative we pound into our heads everyday is that we live in a country where fast food rules, where morning coffee drinks can provide nearly one-quarter of your daily calories before you even get to breakfast, and where you can have pizza topped with Oreos.
And there's the issue that less than a quarter of us exercise regularly, and on average we spend 142 hours a month lounging on our couches, our eyes glued to a TV.
So it's no wonder that the Centers for Disease Control report that more than a staggering 60 percent of adults and 16 percent of children are obese. In the last three decades, obesity has doubled among adults and tripled among children. And experts say there are a range of issues that contribute to it -- the most obvious is of course diet and exercise.
But there is also sleep deprivation (we're sleeping less these days), drugs such as anti-depressants and anti-diabetics, as well as genes, metabolism, culture and socioeconomic status (and I would add advertising, although that hasn't made it to any CDC list).
And there is another factor that has only started gaining attention lately, but may be a hugely important factor, especially in helping to explain why some people who exercise and eat well still can't keep off the pounds. It has to do with chemicals in our environment, particularly in many of the products we come in contact with each day -- from our food to our floors.
There is a lot of emphasis on personal responsibility when it comes to weight, but the prevalence of something scientists are now calling "obesogens" may put a crinkle in that posturing.
Sharon Begley of Newsweek reported:
Evidence has been steadily accumulating that certain hormone-mimicking pollutants, ubiquitous in the food chain, have two previously unsuspected effects. They act on genes in the developing fetus and newborn to turn more precursor cells into fat cells, which stay with you for life. And they may alter metabolic rate, so that the body hoards calories rather than burning them, like a physiological Scrooge.
In addition to the plague of Big Macs, we now also have to figure exposure to chemical pollutants as a contributor to the obesity epidemic.
How Did We Get So Big?
Since studying obesity in adults is tricky due to the high number of factors, the most compelling research on the subject has come from a study from the Harvard School of Public Health in 2006 that looked at medical records of more that 120,000 kids over a 22-year period.
What the researchers found was that "the prevalence of overweight children less than 6 years old jumped 59 percent, from 6.3 to 10 percent." And even more shocking, "The results show surprising increases in the number of overweight children up to 6 months old. From 1980 to 2001, the increase in overweight infants ballooned 74 percent."
This is bad news for these kids later in life because "accelerated weight gain in the first few months after birth is associated with obesity later in life," said Matthew Gillman, an associate professor at Harvard Medical School and one of the study's authors.
So what's the connection between chubby babies, the obesity epidemic and chemical pollutants? Actually, significantly more research. (Warning: A lot of mice were harmed to write this story.)
In 2002, an unknown Scottish academic published a paper about the link between obesity and synthetic chemicals, the Newsweek article explains. This eventually triggered some interest from others in the field.
Already in Japan, scientists were finding that bisphenol A (a chemical compound used to make plastic drinking bottles and baby bottles, among other things) pushed certain cells to become fat cells in experiments performed in the lab and also acelerated the growth of existing fat cells. If their results held true outside the lab in people, it would mean that BPA, and potentially other synthetic chemicals, were in fact contributing to obesity.
So researchers kept plugging away.
The next break came from a study done in the U.S on mice that were given low doses of estrogen-micking chemicals, and they were found to gain weight even when given the same amount of food and exercise as other mice.
Then in 2006, Bruce Bloomberg at the University of California, Irvine exposed pregnant mice to a chemical called tributyltin, which is found in marine paints and plastics and often ends up in people through drinking water. Begley writes that he found that, "The offspring were born with more fat already stored, more fat cells, and became 5 to 20 percent fatter by adulthood."
The tributyltin activated a receptor called PPAR gamma, which acts like a switch for cells' fate: in one position it allows cells to remain fibroblasts, in another it guides them to become fat cells. (It is because the diabetes drugs Actos and Avandia activate PPAR gamma that one of their major side effects is obesity.) The effect was so strong and so reliable that Blumberg thought compounds that reprogram cells' fate like this deserved a name of their own: obesogens.
As later tests would show, tributyltin is not the only obesogen that acts on the PPAR pathway, leading to more fat cells. So do some phthalates (used to make vinyl plastics, such as those used in shower curtains and, until the 1990s, plastic food wrap), bisphenol A and perfluoroalkyl compounds (used in stain repellents and nonstick-cooking surfaces).
And more studies confirm the affect on actual people. Begley again:
In 2005, scientists in Spain reported that the more pesticides children were exposed to as fetuses, the greater their risk of being overweight as toddlers. And last January, scientists in Belgium found that children exposed to higher levels of PCBs and DDE (the breakdown product of the pesticide DDT) before birth were fatter than those exposed to lower levels.
Neither study proves causation, but they "support the findings in experimental animals," says [Retha Newbold of the National Institute of Environmental Health Sciences in North Carolina]. They "show a link between exposure to environmental chemicals ... and the development of obesity."
Since then, the research from other areas has been trickling in as well, such as a recent study in Michigan that found prenatal exposure to DDT may be contributing to obesity in women.
It's Not You, It's Everything Around You
Certainly this research doesn't mean that all cases of obesity are the result of chemicals and that factors like diet and exercise aren't important. They still are. But especially for younger kids who are growing up in an increasingly more toxic environment, these chemicals may be all around them (and their moms during pregnancy).
Let's take a look at some of these chemicals.
The "plasticizer" phthalates for instance, are so ubiqutous that an estimated 1 billion pounds are produced each year worldwide. The Environmental Working Group reports that phthalates are found in "toys, food packaging, hoses, raincoats, shower curtains, vinyl flooring, wall coverings, lubricants, adhesives, detergents, nail polish, hair spray and shampoo."
PCBs were used as coolants and lubricants in electric equipment and have also been added to plastics, inks, adhesives, paints, and flame retardants. PCBs are not only into the products we buy but is in the air and water, and many people are exposed to them through eating certain kinds of fish -- especially the ones highest on the food chain.
Bisphenol A (or BPA) is often found in hard plastics, including baby bottles, food-storage containers, water coolers, dental fillings, the lining inside canned goods, sports equipment, CDs, sunglasses ... the list goes on.
All of these are among the much-maligned class of chemicals known as "endocrine disruptors," which responsible for other such feats in nature as sex-changing fish. In humans, we are learning that they are a frightening menace. Joan Melcher of Miller-McCune reports:
In June, the Endocrine Society, a nearly century-old international association of endocrinologists, issued a statement in which its position was clear. In a 50-page paper, the first scientific statement issued by the society, authors wrote: "We present evidence that endocrine disruptors have effects on male and female reproduction, breast development and cancer, prostate cancer, neuroendocrinology, thyroid, metabolism and obesity and cardiovascular endocrinology. Results from animal models, human clinical observations and epidemiology studies converge to implicate EDCs as a significant concern to public health.
Not only are these chemicals everywhere, but are contributing to much more than obesity, as well.
A Public Health Issue
It turns out that being overweight is costly. The CDC reports that in 2000, obesity related health care costs came to $117 billion. And there has been a surge in spending as we are getting more obese and health care costs are skyrocketing.
Begley reports that health care costs are higher for those who are overweight or obese compared to other adults -- about $1,470 more annually.
"If those outsize costs inspire greater efforts to prevent and treat obesity, fine. But if they lead to demonizing the obese -- caricaturing them as indolent pigs raising insurance premiums for the rest of us -- that's a problem, and not only for ethical reasons: It threatens to obscure that one potent cause of weight gain may be largely beyond an individual's control."
And these chemicals that are contributing to obesity are the nexus of environmental and health concerns. The more dangerous chemicals are allowed to proliferate in our air, water, food and the products around our homes, the greater the threat to our own health, and the more of a burden it places on a health care system teetering at the edge of catastrophe.
So what do we do?
"Part of the hesitation to discuss the issue publicly has been rooted in the omnipresence of these chemicals and the dumbfounded response that society would have if pressed to eliminate literally all, or even a majority of, the streams through which they are delivered to us," wrote Rachel Cernansky for Planet Green. "It's a problem that is truly not easy to solve. But the effects of chemicals on human health are becoming clearer by the day, and we just might be close to a tipping point. Obesogens will, for the first time, be a major focus at a government-sponsored meeting this fall."
As scientists and regulators learn more about the links between obesity and endocrine disruptors, you can play it safe by finding ways to detox your home from some of these chemicals and help ban others, such as BPA.
Tara Lohan is a senior editor at AlterNet. You can follow her on Twitter @TaraLohan.