We’ve got two problems in health care: The first is how to make people healthier. The second is how to make them cheaper. There’s long been the unsettling hypothesis, however, that these two things conflict: that making people healthier will make them more expensive, because the healthier you are, the longer you live. It turns out that that’s mostly not true — but there’s one major exception:

Analyzing Medicare data, federal researchers showed that elderly people in good shape at age 70 — meaning they had no difficulties performing tasks of daily living such as walking and shopping — could expect to live to 84.3, and after 70 they had average, cumulative health care bills totaling $136,000. In contrast, less healthy 70-year-olds with at least one limitation in daily-living activities could expect to live to 81.6 — nearly three years less — yet had cumulative medical bills of about $145,000 during their shorter remaining lives...

Unfortunately, there’s a giant exception to the rule that the longer life tends to be a healthier one: Obese people are living longer, thanks to factors such as cholesterol-cutting medicines (as is the entire population), but much of their extra time is spent in ill health, and as a result, their annual medical bills are some 42 percent higher than those of normal-weight people. In fact, the obesity epidemic has greatly increased the prevalence of chronic diseases such as diabetes, but contrary to much of the media coverage on the epidemic, it has had little effect on mortality rates. As the title of one study put it, “Smoking kills, obesity disables.”...

The nation’s obesity bills are just beginning to ramp up, though, and will soon be growing at a pace comparable to the increase in government medical spending due to the graying of boomers. Annual obesity-related health care costs are projected to rise by nearly $265 billion a year between 2008 and 2018, while annual Medicare expenditures are expected to increase by about $360 billion during the same period. And much of the rise in Medicare spending will go toward treating obesity-related diseases. As one researcher noted, when it comes to chronic health problems, being obese is roughly equivalent to being aged by 20 years.