If Ms. Totten and Mr. Hirshberg are correct, the potential for health care savings is huge. A study in the January-February 2009 issue of the journal Health Affairs concluded that 75 percent of the country’s $2.5 trillion in health care spending has to do with four increasingly prevalent chronic diseases: obesity, Type 2 diabetes, heart disease and cancer. Most cases of these diseases, the report stated, are preventable because they are caused by behaviors like poor diets, inadequate exercise and smoking. Obesity alone threatens to overwhelm the system. In a recent study, Kenneth Thorpe, chairman of the department of health policy and management at the Rollins School of Public Health at Emory University, found that if trends continued, annual health care costs related to obesity would total $344 billion by 2018, or more than 20 percent of total health care spending. (It now accounts for 9 percent.) Dr. Thorpe also said that if the incidence of obesity fell to its 1987 level, it would free enough money to cover the nation’s uninsured population.