Scrooge-like reaction to obesity vs. smoking trade-offs: Bah, humbug!

OK. Maybe the holidays are too much on my mind (or I’ve seen “A Christmas Carol” at the Guthrie one too many times). But when I read earlier this week in the New England Journal of Medicine (NEJM) about how obesity may negate many of the health benefits we Americans have reaped from our (finally) declining smoking rates, I instantly thought of Ebenezer Scrooge.

After traipsing around for an evening with the grim Spirit of Christmas Yet to Come, including a visit to his own pathetically lonely gravesite, Scrooge shouts out to his ghostly travel guide, “Tell me! Are these the shadows of things that must be, or are they the shadows of things that might be?”

And I, too, after wandering through the sobering results of the NEJM study, had an equally plaintive question: Tell me, oh public health epidemiologists, are half of us destined, as your projections indicate, to become obese by 2020, or are these simply the shadows of the fatter-bellied bodies that we might have by then?

Let’s hope it’s the latter.  But according to all accounts, including this latest study, the trends aren’t very encouraging.

As a population, we Americans may have only, um, a ghost of a chance of avoiding the health consequences of our ever-increasing girths.

And one of those consequences may be a shorter life.

What the study found
The NEJM study examined, for the first time, the joint effects of two competing trends in the United States: the increase in obesity (defined as a body mass index, or BMI, of 30 or higher) and the decrease in smoking.

Smoking rates have declined by 20 percent in recent years, while obesity rates have increased by 48 percent. 

Currently, smoking accounts for 18 percent of deaths in the United States each year, while obesity is linked to 5 to 15 percent of all deaths.

Using data from national health surveys conducted from the early 1970s through 2006, the NEJM researchers forecasted both the life expectancy and the “quality-adjusted life expectancy” (quality of life from a health perspective, such as not having heart or joint problems that create disabilities) for a typical 18-year-old.

Overall, they projected that life expectancy will increase significantly for that 18-year-old (because of factors unrelated to smoking and obesity) — but not as much as it would if Americans weren’t getting collectively fatter.

Here are the specifics (Remember, these numbers are for populations, not individuals): The researchers estimated that by 2020, life expectancy will increase by 2.44 years for the typical 18-year-old.  Of that increase, 0.31 years will be because of the drop in smoking rates.

But life expectancy will also decrease by 1.02 years as the result of the increase in obesity rates.

Furthermore, if current trends hold, the typical 18-year-old can expect to lose 1.32 years of quality-adjusted life expectancy (in other words, live those years with some kind of health-related disability).

If, however, all of us stopped smoking and maintained a normal weight (BMI under 25) by 2020, our life expectancy would increase by 3.76 years.

The bottom line:  “If past obesity trends continue unchecked,” the authors of the study wrote, “the negative effects on the health of the U.S. population will increasingly outweigh the positive effects gained from declining smoking rates.”

Caveats
The study does have its limitations, of course. It can’t factor in such things as future advances in medicine and public health (such as health insurance for all?) that might affect life expectancy and quality of life. “Historically,” the authors of the study report, “the positive effects of these factors have overwhelmed the negative effects of smoking and obesity.”

Furthermore, the study uses BMI as an indication of obesity. As the authors acknowledge, there’s been an “ongoing debate about the effect of different BMI levels on the risk of death.”

Minnesota’s no different
I spoke about the study Thursday with Jennifer Linde, an assistant professor at the University of Minnesota’s School of Public Health.

“I think it was a nice examination of the available data,” she said. “It was interesting to see that even with the decreases of smoking rates, we still have some work to do.”

Linde, of course, was not surprised by the projection that almost half of American adults are likely to be obese by 2020. “That’s something we’re already very concerned about from a public health standpoint,” she said.

Minnesotans may not be as fat (per capita) as other states, Linde added, but current state trends are still worrisome.

“We’re a relatively healthy state, but we’re seeing changes in childhood obesity and in adult rates that are fairly consistent with other states,” she said.

A cause for optimism?
So, are ever-increasing waistlines the shadows of things that must be or the shadow of things that might be?

Well, there is a sliver of hopeful obesity-related news in the NEJM study:  We’ve been getting fatter at a slightly slower pace of late.

But given our propensity for sugary, high-calorie, high-fat foods and our disdain for physical activity, I’m not all that optimistic that we’ll change our fat-accumulating ways.

Let me put it another way: Bah, humbug.