单选题 3.Born to be Big
In 2006 scientists at the Harvard School of Public Health reported that the prevalence of obesity (肥胖) in infants under 6 months had risen 73 percent since 1980. "This epidemic of obese 6 - month - olds," as Robert Lustig of the University of California, San Francisco, calls it, poses a problem for conventional explanations of the fattening of America. "Since they' re eating only formula (配方奶) or breast milk, and never exactly got a lot of exercise, the obvious explanations for obesity don't work for babies," he points out. "You have to look beyond the obvious. "
The search for the non - obvious has led to an early - life exposure to Paces of chemicals in the environment. Evidence has been steadily accumulating that certain hormone - mimicking pollutants (污染物质), ubiquitous (到处存在的) in the food chain, have two previously effects. They act on genes in the developing fetus (胎儿) and newborn to turn more precursor (前体) cells into fat cells, which stay with you for life. And they may alter metabolic (新陈代谢的) rate, so that the body saves calories rather than burning them. "The evidence now emerging says that being overweight is not just the result of personal choices about what you eat, combined with inactivity," says Retha Newbold of the National Institute of Environmental Health Sciences (NIEHS). " Exposure to environmental chemicals during development may he contributing to the obesity epidemic. "They are not the cause of extra pounds in every person who is overweight but environmental chemicals may well account for a good part of the current epidemic, especially in those under 50.
The new thinking about obesity comes at a critical time politically. As the debate over health care shines a light on the country's unsustainable spending on doctors, hospitals, and drugs, the obese make tempting scapegoats (替罪羊). About 60 percent of Americans are overweight or obese, and their health - care costs are higher: $3,400 in annual spending for a normal- weight adult versus $ 4,870 for an obese adult, mostly due to their higher levels of type 2 diabetes, heart disease, and other conditions. If those outsize costs inspire greater efforts to prevent and treat obesity, fine. But if they lead to demonizing (妖魔化) the obese - caricaturing (画成漫画讽刺) them as lazy pigs raising insurance premiums (保险费) for the rest of us -that' s a problem, and not only for ethical reasons: it threatens to obscure (使不明显) that one potent cause of weight gain may be largely beyond an individual's control.