I’m going to tell you something that might shock you: Science can’t prove anything. I know, I sounded like a creationist there for a second, but hear me out. The best way to support a theory is to submit it to a test where, if you don’t get the results you expected, the theory cannot possibly be true. For instance, if there were no overlap between the DNA of humans and the DNA of other primates, evolution would have to be overturned. When a test like that fails, it’s a pretty damn good indicator that the theory, or at least that part of the theory, is wrong. But if you get the expected results, it absolutely does NOT prove that the theory is right. It just proves that it could be. And since most theories are awfully complex, it’s pretty hard to prove them wrong either; you can’t always come up with a plausible risky test that would defeat the whole thing, since you’re often looking at multiple factors and sometimes at the wrong ones. Studies contribute to a greater dialogue; they increase the vocabulary we have to interpret the world. But they don’t “prove” things. They don’t “lay questions to rest.” This is generally how they’re reported, but it’s just not what they do.
Take the study in today’s New England Journal of Medicine which is being touted as “proving” that gastric bypasses are better for you than being fat. (The link goes to Reuters, but if you want a more balanced approach, check out the WaPo treatment.) Certainly there are things reporters won’t tell you – like the fact that suicide rates were three times higher in the surgery group (the AP report expressed confusion over the higher non-disease death rate among surgery patients – “my goodness, whyever could that be?” – but it’s not too mysterious when you look at the numbers). Or the fact that even in the “severely obese,” who could of course drop dead any minute if popular opinion is to be believed, there were only 321 deaths out of 7795 over the study period (compared to 213 in the bypass group – just over 4 percent versus just under 3 percent). Or the fact that many of the gastric bypass patients were probably still fat after surgery (to be fair, the study didn’t look at this either; another study in the same NEJM saw weight losses of 14 to 25 percent, but many of those were not gastric bypass surgeries).
But picking over the reporting is Kate’s territory, and she does it well; I’m not gonna step on her toes. I’m looking at the actual study numbers right now, though, and I have to tell you: they’re statistically significant and the methodology is fairly sound. The BMI cutoff for “severely obese” was 35, which I can quibble with – that’s 204 pounds on a 5’4” woman, hardly bedridden – but the average BMI was in fact in the range that has been associated with genuine health risks. Brian worried that deaths due to surgery had been quietly “corrected for,” and it’s possible – I don’t see any clear evidence either way – but it would be deaths on the operating table only, since they take time of surgery as the baseline. (They do mention, though, that post-surgical deaths might have been low — about the same rate as the controls — because the procedure was performed by excellent, experienced surgeons.) They basically did their homework. Their results should be heeded.
But they haven’t proven that obesity increases mortality, or that gastric bypass surgery is good for you, or that losing weight will save your life. That’s not how science works. They’ve contributed to the conversation, and their contribution is sound, but it will be interpreted much differently in the current context – surrounded by studies funded by the diet and weight-loss industry, couched in moral panic about the dangers of fat – than it would be in the context I would consider fair, where studies focus on habits and not mass, and scientists question whether weight itself can hurt you or whether perhaps unhealthy behavior is unhealthy across the board. And, of course, where dieting is revealed as one of the unhealthiest of unhealthy behaviors.
For instance, looking at these numbers, I’m inclined to say it looks pretty likely that for a (small) subset of the population, drastic measures for weight loss are, in the long term, less risky than continuing on a frankly self-destructive path. Within the popular paradigm, this is easily interpreted: fat kills, so less fat kills less, even when the weight loss comes at the expense of digestive integrity. But here’s my HAES interpretation: people who get WLS are generally required or forced to adopt good habits, verging on the orthorexic. You physically cannot overeat (or even eat normally), and you can’t keep down “bad” foods. Weight loss surgery itself doesn’t make you exercise, but exercise is generally a precondition – take care of yourself or you can’t get your stomach amputated! And some very fat people who get surgery will find themselves more mobile and therefore able to exercise for the first time in a long while. Plus, they may begin to value themselves for the first time in their life, and thus take more care of their health. Of course, some will feel despair, accounting for the astronomically higher suicide rate. But we can assume that many will lose weight for at least the first few years, and that they will consequently achieve a higher status in a fatphobic culture, both as No Longer Fat and as Properly Self-Flagellating (nothing says “I know I’m a disgusting pig and I repent” than having your guts cut out). They will be treated better by their doctors. They will treat themselves better. They will inch towards Health at Any Somewhat Smaller Size. It seems reasonable that this could make the modest difference between a 2.7 percent and a 4.1 percent death rate. (And for anyone inclined to say Occam’s Razor – if fatter people die more, death must be caused by fat! – I ask you to look me in the eye and tell me the higher rate for almost all diseases among African Americans is due to skin color.)
The study doesn’t “prove” my interpretation either, and it doesn’t disprove it. It adds a few words to the dialogue, that’s all. In the conversation science is having right now, my version isn’t even audible (in fact, science is sticking its fingers in its ears and going “la la la”). In the conversation that it could be having, this perfectly satisfactory study’s perfectly valid conclusions fit in just as nicely, if not better.
Because we diverge from conventional wisdom, we’re going to get accused – Kate certainly has been accused – of ignoring all evidence that doesn’t fit our preconceived notions. I can’t really be offended by this, because it’s such a common and almost inevitable human behavior that I understand why people are quick to diagnose it. (Well okay, I’m a little offended, but only because critical thinking is my job, so I irrationally expect people to assume better of me.) But you know, science isn’t immune to this behavior any more than its consumers are. Experiments are performed, carried out, and interpreted within a paradigm. They contribute to that paradigm, or they contribute to something new brewing on the horizon, or sometimes they contribute to both. What they don’t do is PROVE a damn thing.