By Edward Hadas The opinions expressed are his own.

Americans are both the fattest people in the world and the biggest spenders on health care. Both those facts can be traced, at least in part, to a common attitude.

First a few numbers. The latest global handbook from the Organization for Economic Co-operation and Development (OECD) shows that 34 percent of Americans are obese by the criteria of the World Health Organization. In health care spending, the United States leads with 17 percent of GDP. In both categories, U.S. numbers are almost twice as high as the average numbers of OECD members.

The extra fat accounts for only a small portion of the extra American spending on health care. Researchers recently estimated that the medical expenses caused by obesity, which is connected to problems such as high blood pressure, heart disease and diabetes, amounted to $147 billion in 2008. That number suggests that even if Americans were no fatter than the OECD average, they would only spend 3 percent less on health care than they do now.

I believe there is a more significant connection between the obesity problem and the amount Americans spend on health care than these numbers suggest. Both the choice to eat too much and the choice to pay up for almost everything labelled “medical expense” are spawned by an attitude which can be called health willfulness. The United States leads the world in this attitude, but it, along with obesity and health care spending, is probably on the rise almost everywhere. It helps explain why spending on health care increased from 4 to 10 percent of GDP since 1960 for the entire OECD.

Health willfulness is the belief that it is my right to decide what to do with my body. If I want to eat without concern for my health, so be it. When it comes to health care, I expect the modern medical system to satisfy my desires, whether for help in getting slim again or for heroic efforts to prolong my life. Money should not matter.