Earlier this week, the Journal of the American Medical Association came out with a huge study of obesity that concludes that the obesity hysterics are, indeed, hysterical. Their results indicate that being moderately overweight or even very mildly obese doesn’t make you more likely to die than a thin person. In fact, it may make you less likely to die, to the tune of 6%. (Severe obesity, however, did show a strong connection to higher death rates).

Now you would think that this would be greeted with some skeptical enthusiasm. If the results are born out by further study, it would mean we do not have a massive pending public health crisis on our hands. It means that instead of using cattle prods to get moderately overweight people into the gym, we can concentrate on really obese people.

So is the health community greeting this with relief? Not exactly:

That’s the wrong conclusion, according to epidemiologists. They insist that, in general, excess weight is dangerous. But then they have to explain why the mortality-to-weight correlation runs the wrong way. The result is a messy, collective scramble for excuses and explanations that can make the new data fit the old ideas.

William Saletan at Slate lists a dozen different explanations for why this study is wrong, definitely wrong, absolutely wrong, no sir. Most of these cross him (and me) as trying to rationalize away an inconvenient scientific result.

To go through them:

The difference is barely significant. As Saletan points out, they’d think 6% was significant if it went the other way.

Death risk is the wrong standard. Maybe there’s something to this if obesity causes joint problems or other quality of life issues. That’s a discussion to have. However, we’ve been told for decades that fat is killing us; that even being a bit overweight is deadly. If they want to change the conversation, that’s fine. But at least admit that they were over-reaching in their last conversation.

Overweight is too close to obese. I want to see some longitudinal data showing that being overweight inevitably leads to obesity. It’s highly likely that some people — most, maybe — level out at a weight slightly higher than ideal. And, anyway, that’s changing the subject again. They haven’t been focusing laser-like on the morbidly obese; they’ve been telling those of us with a bit of a spare tire that we’re ruining the country.

The dangers of being underweight hide the dangers of being overweight. They’re claiming that because underweight people are health risks, this skews the sample. This might be true. But, as Saletan notes, to account for this, you have to shift the scale so that those who are overweight become normal. So … they’re conceding the point, I guess.

Some kinds of fat are worse than others. I’ll address this in my post-bullet-point BMI rant, but I suspect this is bullshit too. The idea that belly fat is particularly dangerous is questionable at best.

Fat helps you survive some diseases and Fat protects you against injury.. I combined these two points because both are an admission that there are some benefits to being a bit overweight. The thing is that those benefits are just as real as the costs. The obesity debate has long been dominated by a particularly insidious kind of political bullshit: cost without benefit analysis. Now that the data are against them, they suddenly want to talk about the benefits of being overweight (so that they can discount them). Again, had the data indicated otherwise, they would not be talking about this.

Muscular people inflate the survival rate of the fat group. See my post-bullet point BMI rant.

Sick people depress the survival rate of the “normal” group. Saletan notes this was addressed in the study. So … bullshit. And wait a minute; aren’t obese people supposed to be sicker than thin people? Wasn’t that offered up as an explanation for these data like five bullet points ago?

Overweight gets you more medical attention and intervention. Ah, now the “it’s because we’re so awesome” argument. They are saying that because of their hysterical focus on weight, we’ve actually improved outcomes for overweight people. That’s possible. But … data, please. In God we trust. All others must bring data.

Medicine has made fat less harmful. This may be the first legitimate argument in the entire thing. But it’s worth noting that a lot of medicine is also focused on … weight loss. And of the medicines that make obesity less deadly, most are either of dubious help (statins) or of very long standing (insulin). Still, I’ll concede that being fat is a lot less deadly in 2012 than it probably was in 1992. Heart attack survival rates alone have boomed in the last twenty years. However, it’s worth noting that this does not explain away the data. If being overweight makes you more likely to have a heart attack, improved medicine would decrease the mortality advantage of thin people, not invert it. No matter how high the heart attack survival rate goes, you’re still more likely to die if you’re more likely to have one.

Overweight doesn’t mean you’re getting fat. It means you’re resisting obesity. This is the complete opposite of what they’ve been saying for twenty years and the complete opposite of what they said earlier. We were just told, nine bullet points ago, that being overweight is the road to obesity. Now we’re told being overweight means you stopped getting there. Which is it? And if this is the case, then maybe being a bit overweight isn’t a bad thing after all if it gets you on the damned treadmill once a while.

Here’s the thing: the entire discipline of public health would be much more useful if we simply dumped the Fucking Useless BMI (hereafter FUBMI). Why on Earth we decided to use a bit of 19th century pseudoscience as our end-all, be-all for measuring health mystifies me.

We all have heard about the muscle thing. Muscular people have higher FUBMI’s and better health. In grad school, I worked out for a while and my BMI went up because I added muscle. But I felt great.

But the muscle thing isn’t the only reason to discount FUBMI. It’s that some people simply have bigger bodies and bigger frames. I have big shoulders and muscular legs, as do many men. There are lots of women who have big hips, no matter how much they starve themselves. None of us is ever going to be in the ideal weight range unless we get down to death camp survivor levels. Does that make sense?

The FUBMI thing reached its awful nadir in public schools, where children were sometimes weighed and shamed in front of their classmates. Childhood obesity is something to be worried about, no question. But using the FUBMI in those circumstances is insane. Any parent knows that children can cycle quite a bit, packing on some weight right before a growth spurt. In just five years, I’ve watched my daughter’s belly get big for a while and then shrink again when the growth spurt hit. I saw her FUBMI go up and down on the doctor’s charts because she was quite a bit head of the growth curves. Fortunately, our pediatrician we smart enough to ignore the FUBMI and concentrate on the healthy active girl in front of him. Many pediatricians and teachers are not that smart and start talking about diets and portion control for toddlers.

The FUBMI is a piece of shit. It has distorted and ruined any scientific discussion of obesity. In the article they talk about slightly better things like waist-to-hip ratios and body-fat percentages. But those are just fancier FUBMI’s. Blood pressure, blood lipids, glucose, cardio-respiratory fitness — that’s useful. But also more difficult and more expensive to measure.

(Part of me wonders if there’s a wisdom of crowds thing going on here. Obesity has leveled off in the last few years despite predictions that it would continue to rocket upward. I’m wondering if we’re finding a level that is the right intersection of health, happiness and a life not spent crying over the scale. Obviously, there’s a distribution: some people at “ideal” weight, some people obese. But I would not be terribly surprised — a little surprised, but not terribly — if research shows that we’re leveling off at level that acceptably trades health risk for happiness.)

Frankly, I think what this study means is that it’s back to the drawing board on obesity. I don’t think this study shows that obesity isn’t bad for you (and it doesn’t) or that being overweight isn’t necessarily bad. I think it shows that our obsession with weight and in particular the FUBMI has been wrong-headed. Fitness, diet, lifestyle: these are far more important.

We need to refocus on the inputs. Encourage people to eat better and get exercise and get off the couch not because it will make them lose weight and look like Heidi Klum or something but because those things are good things in and of themselves. If you lose weight and look good, well, that’s low-calorie gravy. But the inputs are what matters, not the outputs.

An overweight person who gets regular exercise is in better health than a skinny person who doesn’t. Most people who exercise do not lose a lot of weight unless they are obese because their bodies, told by millions of years of evolution that losing weight is a bad thing, will make them eat more to compensate. They then get discouraged and quit. This travesty results from a wrong-headed approach to public health and our obsession with weight the the FUBMI.

Encourage healthy lifestyles. Let evolution and the wisdom of crowds handle the rest.

(And when I say “encourage people” I don’t mean government. I mean society at large: doctors, public health advocates, nurses. You know, people who actually do stuff.)