This article was published in the February issue of Environmental Health Perspectives. Excerpt below.
Obesity is rising steadily around the world. Convincing evidence suggests that diet and activity level are not the only factors in this trend—chemical “obesogens” may alter human metabolism and predispose some people to gain weight. Fetal and early-life exposures to certain obesogens may alter some individuals’ metabolism and fat-cell makeup for life. Other obesogenic effects are linked to adulthood exposures.
Obesity has risen steadily in the United States over the past 150 years, with a marked uptick in recent decades. In the United States today more than 35% of adults and nearly 17% of children aged 2–19 years are obese. Obesity plagues people not just in the United States but worldwide, including, increasingly, developing countries. Even animals—pets, laboratory animals, and urban rats—have experienced increases in average body weight over the past several decades, trends not necessarily explained by diet and exercise. In the words of Robert H. Lustig, a professor of clinical pediatrics at the University of California, San Francisco, “[E]ven those at the lower end of the BMI [body mass index] curve are gaining weight. Whatever is happening is happening to everyone, suggesting an environmental trigger.”
Many in the medical and exercise physiology communities remain wedded to poor diet and lack of exercise as the sole causes of obesity. However, researchers are gathering convincing evidence of chemical “obesogens”—dietary, pharmaceutical, and industrial compounds that may alter metabolic processes and predispose some people to gain weight.