"The modern lifestyle of super-sized french fries and couch potatoes often takes the blame for the rising rates of obesity and diabetes in the U.S. -- perhaps rightly so. But growing evidence suggests another factor in the dual epidemics: modern chemicals.
Exposure to even minuscule amounts of synthesized substances -- used in everything from pesticides to water bottles -- can scramble hormone signals, scientists say. This interference can trick fat cells into taking in more fat or mislead the pancreas into secreting excess insulin, a hormone that regulates the breakdown of fat and carbohydrates.
Among the most ubiquitous and scrutinized of these so-called endocrine disruptors is bisphenol A, better known as BPA. The chemical is a common ingredient in plastics and food-can linings. The consequences of the continued widespread use of BPA could be most dire for pregnant women and developing fetuses, who appear to be particularly sensitive.
"The fetus is not only exposed to BPA but also to higher levels of insulin from the mother, making the environment for the fetus even more disruptive," says Nadal. "This is a very delicate period."
Previous studies have suggested that the environmental chemicals in the womb can preprogram weight gain later in life. BPA, for example, may tell a growing fetus to develop more fat cells.
Nadal adds that BPA is just one of a larger cocktail of at least 20 endocrine disruptors commonly used in everyday items, including phthalates, nicotine, dioxin, arsenic and tributyltin. Further, obesity and diabetes aren't the only risks posed by the chemicals. Studies also hint at links with cancer, infertility, heart disease and cognitive problems.
Overall, half of the developed world is now overweight and one in six is obese -- about double the numbers of 30 years ago. Approximately 250 million people suffer from diabetes worldwide.
Sure, our lifestyle has changed over the decades in parallel with the increased use of BPA. Yet scientists have noticed the same fattening trend in newborns, lab rodents, pets and wildlife that live in close proximity to humans. Have babies or mice really changed how much they eat or exercise? Experts highlight this as further evidence that more than just caloric intake is driving the current epidemics of obesity and Type 2 diabetes.
"The scary thing is, this is occurring in children. Thirty years ago, we called Type 2 diabetes 'adult-onset,'" vom Saal says. That's not the case anymore.