To listen to President Obama, or to just about anyone else in the health care debate, you would think that the biggest problem with health care in America is the system itself - perverse incentives, inefficiencies, unnecessary tests and procedures, lack of competition, and greed. No one disputes that the $2.3 trillion we devote to the health care industry is often spent unwisely, but the fact that the United States spends twice as much per person as most European countries on health care can be substantially explained, as a study released last month says, by our being fatter. Even the most efficient health care system that the administration could hope to devise would still confront a rising tide of chronic disease linked to diet. That's why our success in bringing health care costs under control ultimately depends on whether Washington can summon the political will to take on and reform a second, even more powerful industry: the food industry. According to the Centers for Disease Control and Prevention, three-quarters of health care spending now goes to treat preventable chronic diseases." Not all of these diseases are linked to diet - there's smoking, for instance - but many, if not most, of them are. We're spending $147 billion to treat obesity, $116 billion to treat diabetes, and hundreds of billions more to treat cardiovascular disease and the many types of cancer that have been linked to the so-called Western diet. One recent study estimated that 30 percent of the increase in health care spending over the past 20 years could be attributed to the soaring rate of obesity, a condition that now accounts for nearly a tenth of all spending on health care. The American way of eating has become the elephant in the room in the debate over health care.