Obesity is generally discussed in terms of caloric intake (how much a person eats) and energy output (how much a person exercises).
However, according to a University of Missouri-Columbia scientist, environmental chemicals found in everyday plastics and pesticides also may influence obesity. Frederick vom Saal, professor of biological sciences in MU's College of Arts and Science, has found that when fetuses are exposed to these chemicals, the way their genes function may be altered to make them more prone to obesity and disease.
"Certain environmental substances called endocrine-disrupting chemicals can change the functioning of a fetus's genes, altering a baby's metabolic system and predisposing him or her to obesity. This individual could eat the same thing and exercise the same amount as someone with a normal metabolic system, but he or she would become obese, while the other person remained thin. This is a serious problem because obesity puts people at risk for other problems, including cancer, diabetes, cardiovascular disease and hypertension," vom Saal said.
Using lab mice, vom Saal has studied the effects of endocrine-disrupting chemicals, including bisphenol-A, which recently made news in San Francisco, where controversy has ensued over an ordinance that seeks to ban its use in children's products. In vom Saal's recent study, which he will present at the 2007 Annual Meeting of the American Association for the Advancement of Science (AAAS), he found that endocrine-disrupting chemicals cause mice to be born at very low birth weights and then gain abnormally large amounts of weight in a short period of time, more than doubling their body weight in just seven days. Vom Saal followed the mice as they got older and found that these mice were obese throughout their lives. He said studies of low-birth-weight children have shown a similar overcompensation after birth, resulting in lifelong obesity.
"The babies are born with a low body weight and a metabolic system that's been programmed for starvation. This is called a 'thrifty phenotype,' a system designed to maximize the use of all food taken into the body. The problem comes when the baby isn't born into a world of starvation, but into a world of fast food restaurants and fatty foods," vom Saal said.