Are Chemicals Making You Fat?

Many people say the obesity epidemic could be solved if we just got off our butt to hit the gym and stopped eating so many Big Macs. Diet and exercise do play a huge role in what we weigh, of course, but there’s one glitch with this theory: Over the past quarter century, the incidence of obesity has risen most markedly—by a whopping 74 percent—not in adults or children, but in infants.

In fact, six-month-olds today are fatter than they were in 1980, despite the fact that birth weights overall have been decreasing—a finding that makes some scientists wonder whether environmental chemicals could be causing babies to rapidly gain weight after birth. Bruce Blumberg, Ph.D., a biologist at the University of California-Irvine, is so concerned that these chemicals play a significant role in the rise in obesity that he considers them “obesogens.” “Not too long ago, no one would’ve believed there was such a thing as an obesogen and that anything except eating too much could make you fat,” he says. But in Blumberg’s research, TBT, a common chemical used to make PVC plastic (of the sort found in some shower curtains), caused mice to develop extra fat cells. And when Blumberg exposed pregnant mice to the chemical, their pups grew to be up to 15 percent fatter than mice that hadn’t been exposed.

Now, this is animal research, and no one knows just how widely humans are exposed to TBT, which hasn’t been tested extensively in humans. But last year researchers at the University at Albany in New York found traces of the chemical in every single sample of house dust they analyzed.

BPA and phthalates, chemicals used to make plastic flexible, may also impact your weight. Boston University research found that teen girls with greater levels of a certain phthalate in their urine were at higher BMIs than those without. Another study found that Americans who were most exposed to both chemicals were more at risk of developing diabetes. As a double whammy, BPA and some pesticides may even disrupt our body’s ability to regulate blood sugar and hunger—two key factors in losing weight. “For me, there’s no doubt common chemicals are playing a role in obesity and related diseases,” says Richard Stahlhut, M.D., an environmental health scientist at the University of Rochester in New York. “Some overweight people have been taking a beating for diseases that are not their fault.”

The good news, some researchers say, is that we may be able to lose weight not by starving ourselves but by avoiding obesogens. While researching his book The New American Diet, journalist Stephen Perrine asked 400 people to cut their obesogen exposure for six weeks. “We had them swap out foods that tended to be high in obesogens, such as canned foods and grain-fed meats, for versions of these foods with lower chemical loads,” Perrine says. They were still allowed to eat burgers and pork chops, just ones that were free-range and hormone-free. After six weeks, the subjects had lost, on average, 15 pounds. Filling your plate with (organic) green leafy vegetables like spinach and kale, which are high in folate, also helps.