Health Risk of Obesity is a Numbers Game: Weight, Overweight and Statistics
No 30-second sound-bite can really summarize research that took years. Learn how to understand statistics.
You've probably heard some gleeful gloating lately about how death rates from obesity were grossly overstated in research released last year, and that it now seems that slightly overweight people might actually have a lower risk of death than normal-weight folks.
If you haven't heard it yet, you will. Over and over and over, probably. Just keep in mind that numbers can be crunched a lot of different ways, and the folks at the Centers for Disease Control will no doubt keep crunching them.
But while the jury is still out, ask yourself this: "If obesity is only the 7th leading cause of preventable death, instead of the 2nd, does that make it any easier for me to breathe when I'm climbing the stairs?"
The new numbers and conclusions, understandably, may be more welcome by more of the public. The Journal of the American Medical Association in April published the new research from the CDC, and it seems to contradict the previous finding that nearly 400,000 Americans a year die because of their excess weight.
Health Risk: "The new data suggest that the actual number is closer to 110,000 each year, and once that is adjusted for some statistical advantages of a little extra weight, the number drops to around 25,000."
You may be wondering just what does that mean? "Statistical advantages?"
Good question. Mark Twain's cynical reflection on number crunching comes to mind.
"There are three kinds of lies," he said. "Lies, damn lies and statistics."
Indeed, some contemporary cynics are hailing the new CDC research as evidence that all the previous research linking obesity and early death was the result of some vast, health-fixated conspiracy. The reality is more prosaic: newer data and more sophisticated analysis probably just produced different results.
But it's not even just that, according to the authors of the new research.
"The impact of obesity on mortality may have decreased over time, perhaps because of improvements in public health and medical care," they wrote.
And maybe there's the rub. Because more and more people in America are more and more overweight. And obesity causes all sorts of medical problems for most people. These things aren't disputed. But it's also true that, on the whole, we're also getting better and better at taking care of ourselves, no matter what our size or condition.
Health Risk: "Tremendous resources have been devoted to examining the causes and consequences of Americans' eating habits and burgeoning weight over the last couple decades. In that period, we've advanced by leaps and bounds in our understanding of heart disease, diabetes, exercise, genetics, medicines, nutrition and lifestyle factors that play into the whole complex issue."
And it's not idle study. Treatments are being developed even as new data are gathered and analyzed. All the science is evolving, and everything happens so much more quickly today that it's almost impossible to try to get all the latest information to coalesce into one comprehensive overarching Truth, with a capital T.
The best we can do is keep listening and learning and watching with an open mind, and a real eye to how the best new information is relevant to our own health.
Health Risk: "Because ultimately, like most statistics, broad sweeping numbers about national mortality risk are pretty meaningless to your personal situation. But if you've got heart arrhythmias, that matters to you. If you've got a wild fluctuations in your blood sugar, that matters to you. If you can't get into your jeans, that matters to you, even if the only effects you suffer are social or emotional.
Those things impair the quality of your life, and really, most people are more interested in how they're going to live than why they're going to die.
But then what about this piece that seems to indicate that slightly overweight people actually have a lower risk of death than normal-weight people?
Be careful with that tricky statistic and expect to hear it misused a lot in coming months. It's quite like the infamous data on the dangers of bread. You haven't heard? Well, just look at the statistics:
* More than 98 percent of convicted felons are bread users.
* Fully HALF of all children who grow up in bread-consuming households score below average on standardized tests.
* More than 90 percent of violent crimes are committed within 24 hours of eating bread.
* Bread is baked at temperatures as high as 400 degrees, which can kill an adult in less than one minute!
* Most American bread eaters don't even notice when statistics are misused.
It's obvious and silly when it's illustrated with bread factoids, but this is classic misuse of data. There's just no causal relationship! Yet we're already seeing exactly this sort of thing with people citing the "slightly higher weight/slightly lower risk" factoid from the recent study.
The subjects' risk wasn't lower because they were a little overweight. The study's authors acknowledged that. In fact, they noted that they didn't yet have an explanation for that paradoxical oddity.
But they'll speculate on it. And you can too. Consider: If you're a little overweight, and you're a little sedentary, and have little activity, you're probably limiting your exposure to other mortality risks. It's a good bet you won't get hit by a car if you're home eating corn chips in front of the TV. So, that could lower your death risk. That is, as long as you don't eat so many corn chips that you become obese, which will then raise your death risk.
Either way, you still have to worry about how you'll feel while you're sitting there. We tell patients that the "fit and fat" phenomenon is real, and that some people actually can by physically fit, yet still carry excess body weight and show no medical disadvantages from it. But that's not the same as being protected by it.
And it's not the same as having your life improved by it. Whatever the new data are on mortality and obesity, there are other, pretty long-standing data about the life-impairing effects of obesity, such as increased likelihood of debilitating diseases, joint replacements, high-risk pregnancies, surgical complications, physical limitations, insomnia, discrimination, lower salaries, social discomfort and self-esteem issues.
When all is said and done, everyone ultimately has the same death risk. Fat or slim, active or idle, well or ailing, we're all at extremely high risk of dying eventually. In fact, it's pretty much guaranteed. Science and medicine just haven't figured out how to change that outcome.
Until they do, it's still best to prevent, resist, and when possible overcome obesity. Not just because, in general, it's causing more death, but because in individuals, it simply leaves less room for life.