Los Angeles

THE inexorable rise in health care spending, as all of us know, is a problem. But what’s truly infuriating, as we watch America’s medical bill soar, is that our conversation has focused almost exclusively on how to pay for that care, not on reducing our need for it. In the endless debate about “health care reform,” few have zeroed in on the practical actions we should be taking now to make Americans healthier.

An exception is Mayor Michael R. Bloomberg of New York, who is setting new standards that we would do well to adopt as a nation. In the last several years, he’s changed the city’s health code to mandate restrictions on sodas and trans fats — products that, when consumed over the long term, harm people. These new rules will undoubtedly improve New Yorkers’ health in years to come.

Such bold moves prompt a provocative question: when does regulating a person’s habits in the name of good health become our moral and social duty? The answer, I suggest, is a two-parter: first, when the scientific data clearly and overwhelmingly demonstrate that one behavior or another can substantially reduce — or, conversely, raise — a person’s risk of disease; and second, when all of us are stuck paying for one another’s medical bills (which is what we do now, by way of Medicare, Medicaid and other taxpayer-financed health care programs).

In such cases, encouraging a healthy behavior, or discouraging an unhealthy one, ought to be a matter of public policy — which is why, for instance, we insist on vaccinating children for the measles, mumps, rubella and polio; we know these preventive strategies save lives.