Passage Three

Few foods are more alluring than chocolate. "Chocolate is a drug of abuse in its own category," jokes Dr. Louis Aronne. "It’s ahnost as if people have chocolate receptors in their brains. " That may not be too far off the mark. In a recent book called "Breaking the Food Seduction," Dr. Neal Barnard contends that certain foods—including chocolate, cheese, red meat and practically anything combining sugar and fat—are just plain addictive. " It’s not that you lack willpower. These foods stimulate the release of chemicals in the brain’s pleasure center that keep you hooked. " Besides tapping the brain’s own "feel good" chemicals, Barnard says, some of these foods contain drug-like molecules (分子) of of their own. Cheese delivers casomorphins, the same compounds in a mother’s milk that help an infant bond during nursing, he says, but cheese is even more powerful, because it delivers casomorphins in an undiluted form. The result: "We’re bonding to our refrigerators. " Other scientists doubt these drug-like compounds have enough force to make the foods addictive. But no one denies that fat and sugar exert a strong appeal. The brain is designed to reward eating and other behaviors that promote survival. And throughout history, with food relatively hard to come by, what prmnoted survival better than calorie-dense foods packed with fat and sugar Besides, fat and sugar also calm the brain, lowering levels of stress hormones. "That’s why we call them comfort foods," says physiologist Mary Dallman. But comfort is different from addiction. In classic addiction, the brain grows less sensitive to a pleasurable substance, and the addict requires higher and higher doses to derive the same rewards. Can food cause that kind of change Perhaps. In a new study, Ann Kelley offered rats either plain water or a high-calorie chocolate drink. Over a two-week period, the animals drank more and more chocolate, but produced fewer brain opiates(镇静剂) in response. "You see the same thing in rats on or heroin," she says. Admittedly, some foods can be hard to stop eating. But these foods are less habit-forming than alcohol—and most people can enjoy a drink without becoming alcoholic. The real problem today may be that we’re constantly surrounded with food—and can’t undo millions of years of evolution.

Which of the following CANNOT explain our addiction to sugar and fat