He rattles off the usual suspects — stress, food portion sizes, lack of exercise, and others. The National Academies research panel reviewed evidence for many possible culprits, ranging from lack of access to medical care to seatbelt use to poverty. Nearly half of the Shorter Lives report is devoted to exploring that evidence, but the researchers concluded that no single factor fully explains the U.S. health disadvantage.

Shorter Lives did refute some easy assumptions. “When you talk to the general public, they say, ‘We want people to live longer so let’s invest more in medicine,’” Kaplan said. “Health care certainly is a contributor to life expectancy, but the report did a very good job of clarifying that achieving better health requires more than just providing health care.”

Researchers also looked at the effect of individual behaviors. For example, eating a high-fat diet in early life can lead to obesity, which can cause diabetes and heart disease. But why is there so much childhood obesity in America? Shorter Lives points to government policies that encourage production of cheap, fattening foods; school district decisions about high-calorie cafeteria menus and vending machine contracts; business decisions about where to locate grocery stores and fast-food outlets; the marketing of electronic devices to children; and neighborhoods that are too unsafe for children to play outside. “Choices may not always be made ‘freely’: they are made in a societal and environmental context,” the report said.