The prevalence of obesity and obesity-related diseases has increased drastically over the past several decades. While there are many culprits to blame for our ever-expanding waistlines, including colossal portion sizes and an increasingly sedentary lifestyle, scientists are exploring the idea that the obesity epidemic may be more complicated than the old "calories in versus calories out" explanation (balancing calories consumed with calories expended). Researchers believe a third factor may be involved: a group of natural and synthetic chemicals called endocrine-disrupting chemicals. Recent research suggests these environmental chemicals, dubbed "obesogens," can alter metabolism and the production and storage of body fat.

Obesogens are environmental chemicals that can disrupt the normal developmental and natural controls over metabolism. Industrial pollutants found in many plastics, food packages, pesticides, and cosmetics are thought have metabolism-altering effects on our genes. Researchers have suggested that obesogens target body proteins that send signals to a developing human fetus to increase production of fat cells. Scientists hypothesize that exposure to these common chemicals at an early age is "programming" infants to be overweight. In infants, these environmental pollutants that seem to mimic certain hormones turn more precursor cells into fat cells that stick around for life. Researchers do warn, however, that obesogens can not be the reason that everyone is overweight. After all, many older adults who were not exposed to nearly as many of these compounds in utero are still overweight or obese, most likely as a result of their lifestyle choices.

There is a scary statistic that prompted researchers to investigate other explanations for the obesity rise. Several years ago, scientists from the Harvard School of Public Health reported an alarming statistic: the prevalence of obesity in infants (under 6 months of age) has risen 73 percent since 1980. This statistic is of particular concern because infants are not eating high-fat, high-calorie foods and remaining sedentary--which are two explanations for the obesity epidemic among adults. Infants consume only breast milk or formula, and they don't exercise; therefore, the typical reasons for obesity don't apply to them.

Of particular concern is the rise in childhood obesity, because once it is in place, obesity is very hard to treat. This is why obesity prevention at an early age is key. Since about 60 percent of the American population is currently overweight or obese (and these number continue to climb), research on obesity causes, prevention strategies, and treatments is warranted during this pivotal time of American healthcare.

The bottom line: We definitely need more research about both obesogens and obesity. Balancing your daily caloric intake with your daily energy expenditure (through a combination of calories used for basal metabolism and calories burned through physical activity) is still your best bet when it comes to achieving and maintaining a healthy weight and, ultimately, a healthy body. If you subscribe to the "better safe than sorry" school of thought, get rid of your plastic food containers and switch over to glass and stainless steel varieties. Also, try eating fewer pre-packaged convenience foods, and aim to buy more locally grown, minimally-processed organic foods. In any case, a diet of more fresh foods will ensure that you take in fewer preservatives and other chemicals.