Thursday Throughput: Not So Fat Obesity Edition
Ettarh R et al., Public domain, via Wikimedia Commons
[ThTh1] In the early 2000’s, a much-ballyhooed study claimed that obesity was causing around 365,000 deaths per year. However, a subsequent study from Katherine Flegal showed that the methodology was flawed. It failed to account for confounding factors like smoking and used very outdated mortality calculations. The actual number of obesity-related deaths was a third of what they were claiming. Moreover, the data showed that, at least in terms of lifespan, being slightly overweight was preferable to being “ideal”.
The response from the healthcare community was…not good. This week, Flegal published a great article detailing the attacks she endured because she had the temerity to buck the obesity consensus, including some from big names in the field. At one point, the Dean of Harvard convened a panel specifically to attack her work, which has held up so far.
I actually wrote about it at the time. I was far more vociferous in 2013 than I am now, using some very technical scientific terms that might cross the layman as profanity. But the attacks on Flegal’s work crossed me as less motivated by scientific rigor and more motivated by not liking the results of her work.
One of the problems our society has is that…we really like our moral panics. And we really like it when science backs up our moral panics. I wrote a few weeks ago about how overpopulation turned out not be a concern. But the response of overpopulation hysterics to the likes of Borlaug or Simon was not relief, but anger. For years, I’ve written that most of the social science on “sex trafficking” is junk and that we do not, in fact, have a giant sex slave industry in this country. But those facts provoke not relief, but anger in those who support the moral panic. We have seen similar reactions to moral panics over satanism, drugs and, hell, even COVID-19. There is a certain group of COVID hysterics on Twitter who are always pushing worst-case scenarios and always getting angry someone dashes cold water on them.
Part of this is human nature. There’s a part of our mind that really wants to believe things are bad. But part of it is deliberate. There is a feeling among many people, including scientists, that you need to predict the end of the world to get people’s attention. There’s a quote that P.J. O’Rourke repeats in All the Trouble in the World in the context of environmental hysteria:
[W]e have to offer up scary scenarios, make simplified dramatic statements, and make little mention of any doubts we have. Each of us has to decide what the right balance is between being effective and being honest.
This is not a good approach to science. The public eventually tires of having their chain pulled like this. We’ve seen with COVID-19 that hysterical predictions tire the public and make them less willing to comply with safety measures.
There’s no question that obesity is a problem in this country and Dr. Flegal would be the first to agree. As someone who needs to shed a couple of stone, I’m living proof of this. But the disastrous turn-of-the-century predictions of skyrocketing obesity have proven incorrect and the scale we are using to judge health appear to be a few pounds too light. That’s good news. And it’s a shame that so much effort was invested into trying to debunk her work on obesity rather than using it as a springboard to better public health policy. Because it seems to me that the more tenable the goal is with Americans’ weight, the more likely they are to make the choices necessary to get there. If you tell me that a weight of 205 will get me to decent health, that’s a reasonable goal I think I can reach. If you tell me that 175 is the goal — a weight I have not seen since I was in college and two inches shorter than I am today — I’m more likely to just say, “screw it, I’m doomed” and reach for some more fries.
[ThTh2] Remember when Betelgeuse dimmed? We may now know why. And it’s a really cool reason why.
[ThTh3] A new paper indicates that COVID-19 infections may cause brain damage. A note of caution, however: this is one study and it’s not entirely clear what the results mean. But it is another reason why I say it will be years before we know the real impact of this pandemic.
[ThTh4] How do you clean dirty statues? How about with bacteria.
[ThTh5] Columbus didn’t prove the world was round. It was known since ancient times, because people could see the shape of the Earth’s shadow during lunar eclipses. Here’s a map of what they thought the world looked like.
Map of the Ancient Roman World from their perspective: Orbis Terrarum. Read more: https://t.co/tDta99KYHi pic.twitter.com/nZRiFVrtSD
— Archaeology & Art (@archaeologyart) June 21, 2021
[ThTh6] It usually takes many decades and exquisite precision to measure the motions of stars. Unless, that is, they are zooming around the giant black hole at the center of the Galaxy.
Fireflies? Nah: stars. This time-lapse video from the NACO instrument on ESO's Very Large Telescope in Chile shows stars orbiting the supermassive black hole that lies at the heart of the Milky Way over a period of nearly 20 years [source: https://t.co/oirYH22Smm] pic.twitter.com/yzjo254oB8
— Massimo (@Rainmaker1973) June 21, 2021
[ThTh7] A really cool proposal for getting water out of the lunar surface: rocket mining. (H/T: Tim Hamilton)
[ThTh8] Mine too.
this illusion broke my brain 🤯 pic.twitter.com/BvgO2TcwFE
— drewcoffman.eth 𝕚𝕤 𝕠𝕟𝕝𝕚𝕟𝕖 🟢 (@DrewCoffman) June 14, 2021
[ThTh9] Nice to know we’re wrecking ground-based astronomy for a satellite communication system that doesn’t work in hot weather. (H/T: Andrew)
[ThTh10] A really amazing thread on cave art. Our ancestors were so clever.
[ThTh11] No, it’s not going to hit us. It will never cross our orbit. But a gigantic comet is making a trip through the Solar System. 2014 UN 271 is one of the biggest comets we’ve ever detected, some 150-200 km across. It is currently headed inward to just about reach the orbit of Saturn in 2031 before it chugs back out to the Oort Cloud. Then we won’t see it again for another 3-5 million years. Right now, it’s way too faint to see except with a big telescope. But maybe it will brighten. Hopefully, I’ll still be writing and you’ll still be reading my words a decade from now when we see what it has in store for us.
the obesity thing: some have posited that some percentage of the “poor health outcomes” in heavier (if not “morbidly obese”) people is that they tend to avoid doctors and while anecdote =/= data, that seems to ring true to me – I went from 1999 to 2012 (when I was refused from giving blood twice because my blood pressure was too high) without seeing a doctor or having a regular doctor, because I went in for a flu shot to a local physician and she wanted to write me a prescription for weight loss medications. (I am heavy, but not obese, and I work out and strive to eat healthfully).
I was fortunate more recently to find a doctor who (mostly) doesn’t make a deal about my weight. (She did mention the 10 or so pounds I gained – which I have since lost – during the pandemic). But yeah, she has regularly commented my blood numbers are better than hers, and that’s the measure of health she prefers to go by. Also the fact that I do the equivalent of a 5K jog (just in a less-high-impact way) most days of the week.
By the most restrictive charts, I should weigh about 140; I was 140 lbs last when Reagan was in office.Report
When I reached a “certain age” my doctor quit nagging about weight entirely. Suddenly it was all about how active I was, and in particular, if I was doing strength training.Report
Note that failure to control for smoking will tend to bias estimates of obesity-related death downwards. Because smoking both increases mortality and suppresses weight gain, it will result in higher mortality rates for people with low BMI.
While the Flegal study was in some ways methodologically superior to contemporary studies, it was still deeply flawed in some very important ways. Baseline morbidity is a huge problem, because there are diseases that, like smoking, tend to a) kill you, and b) cause weight loss, sometimes before diagnosis. This can be an important confounder, especially in age brackets where death is relatively rare; even a small number of people in the normal or underweight category due to cachexia can skew the mortality numbers pretty substantially.
This is a hard problem, but a technique recently developed to sidestep it is to look at the association between lifetime maximum BMI and mortality, rather than BMI at the beginning of the study. With this technique, studies find a relationship between overweight and mortality that’s more in line with pre-Flegal expectations. Note that this does not mean that losing weight is bad for you and pointless, only that losing weight with diet and exercise is hard, and losing weight with an undiagnosed terminal disease is easy (but not recommended!)
BMI is also problematic, because there are two types of weight with contrary effects: Adiposity increases mortality, and lean body mass decreases mortality (or at least predicts lower mortality). Especially for men, body fat percentage can differ by up to 20 percentage points for two people with the same BMI; conversely, among men with the same body fat percentage, BMI can vary by up to 10 points. Do an image search for “bmi body fat correlation” (no quotes), and take a look at the scatterplots from various studies. When we really want to know the relationship between adiposity and mortality, using BMI instead of a true measure of adiposity results in attenuation bias.
While Flegal’s newest paper documents some really bad behavior on the part of some of her colleagues, we should not mistake that for a vindication of her findings.
Also, while it’s true that obesity has not “skyrocketed” in the US in the 21st century, it has continued its inexorable upward climb, with the age-adjusted adult obesity rate increasing by about 10 percentage points since 2000.Report
“There’s a quote that P.J. O’Rourke repeats in All the Trouble in the World in the context of environmental hysteria…”
It was amusing to me that his recent omnibus reprint has all of All The Trouble In The World except that chapter…Report
I’m guessing parts of its — like the Ozone thing — didn’t age well.Report
[ThTh5] Don’t bother; “Columbus proved the religious idiots wrong because they all believed the Earth was flat” is popular myth now, just like “the religious idiots excommunicated Galileo because they believed the Earth was the center of the universe”.Report
He wouldn’t have proven the Earth was round even if it was commonly believed to be flat. He ended up in North America and did not circumnavigate the globe.Report
I wonder if the consensus on the circumference of the Earth changed briefly as a result of Columbus returning successfully from his voyage to the “Indies.” Did everyone just say, “Huh, I guess he was right” for a few years until they figured out that it was actually a totally different continent?Report
My memory is that people had about the right number but thought there wasn’t a landmass. Columbus, IIRC, used some odd arguments about the world being pear-shaped as to why sailing across the other ocean would work. But the correct size of the Earth was known for about 2000 years.Report
Yeah, I went and looked. Eratosthenes had the circumference correct within a couple of percent. Also a remarkably accurate estimate of Earth’s axial tilt. Also a calendar that had 365 days in the year and 366 every fourth year.Report
Two things happened:
First, Strabo, a Greek geographer, philosopher, and historian, wrote about Posidonius’s estimate, which was very close to Eratosthenes’s, but got the numbers wrong. Second, the estimate was in stadia, which were different lengths in Greece and Rome. So just like today, when you can’t trust science reporting and American vs. Imperial measures confuse things, the results got garbled. There seemed to be two different classical estimates of the size of the earth, and Columbus optimistically assumed the smaller one.
That’s a great question about whether Columbus’s return made the incorrect number more popular. No idea.
https://en.wikipedia.org/wiki/Earth%27s_circumference#PosidoniusReport
That’s my understanding as well, but I’m curious about what happened after Columbus returned. Back in 1492, everyone’s saying, “You’ll never make it to the Indies, you idiot. The Earth’s just too damn fat. Like your head.” Then Columbus sails off muttering about how he’s going to show those jerks but good. Then he comes back months later with a tan, saying “Hey, guys. I sent you a postcard from the Indies, but I had to bring it myself because there’s no mail service yet.” When he hands them the postcard and it says, “Suck it, putas! I was right!” do most of them just accept that Columbus was in fact right about the circumference of the Earth? Or did they immediately figure out that there must be another continent in the way?Report
Because it seems to me that the more tenable the goal is with Americans’ weight, the more likely they are to make the choices necessary to get there. If you tell me that a weight of 205 will get me to decent health, that’s a reasonable goal I think I can reach. If you tell me that 175 is the goal — a weight I have not seen since I was in college and two inches shorter than I am today — I’m more likely to just say, “screw it, I’m doomed” and reach for some more fries.
You may be right that many people think this way, but I think it’s the wrong way to look at. Whether the optimal weight for you is 205 or 175, 205 is still better than 235 (again, composition matters, but for simplicity I’ll ignore that here). If you can lose 30 pounds, that’s a win, even if 60 would be better. And it’s not like there’s some magic weight that makes you immortal. The absolute reduction in mortality risk from going from 235 to 205 is probably about the same either way.
Scott Adams has kind of gone off the rails since Trump’s election, but I like his idea about systems vs. goals. What matters is not achieving some arbitrary goal, but having a system that moves you in the direction you want to go and sticking with it.Report
I get into this in the linked post. Concentrate on behavior, not numbers, and we’ll all be better off.Report
ThTh8 – Things that cause a brain to experience a BSD.Report
I spent some years working on video compression algorithm research. There are so many ways to screw with the human vision system.Report
The pen and the gate both appear to go through each other, so it’s a BSDI.Report
The question that occurs to me is, does it only work when we’re viewing a 2D projection of things? In real life with 3D and depth perception, does the same effect happen?Report
Serious hope-things-work-out wishes extended to Our Todd and Brother Burt. The weather forecast I have calls for 112 in Portland, OR on Sunday. While 72 and rain in Fort Collins, CO. Bizarre sh*t going on.Report
108 here in the Puget SoundReport
76 here in the Bay, but 108 in central CA, where my daughter lives.Report