Scott Alexander, (Alexander 2020)
Summary
Discussion, without firm conclusion, regarding the source of the American obesity epidemic.
Thoughts
Perfectionism
A sentence in the beginning of the essay stood out to me:
I’ve been told that another blog called Hyperlipid has a deeper investigation, but I’ve only scratched the surface of them. […] I don’t claim to fully understand these people and I apologize for any misrepresentations I might be making. But the short version is: they all agree that everything went wrong when we switched from saturated to unsaturated fat.
It stands out because Scott specifically mentions the edge of his research and yet published the piece anyway. There is a loud voice in the back of my head whenever I’m writing anything “original” which drives me to go deeper and that stones left unturned will mar my writing. I wouldn’t recommend anyone to actually listen to this voice but it’s damn loud and I’m glad to see a concrete example of someone ignoring it.
“Processed” Food
What food counts as “processed” or “not processed”?
I found myself nodding along to this paragraph as I read. I’ve had the same thought with the same (inferred) sense of exasperation.
Notes
In the 1800s, the average US man weighed about (a) 155 lbs. Today, he weighs about 195. The change is even starker at the extremes. Someone at the 90th percentile of weight back then weighed about 185 lbs; today, he would weigh 320 lbs. Back then, about 1% (a) of men were obese. Today, about 25% are.
[…]
The answer to all these questions seems to be something like “the body is pretty good at regulating its own weight under any diet except modern American processed food.” But what aspect of processed food makes it bad?
[…]
The only common villain everyone agrees on in the obesity story is “processed food”. I’ve previously found this frustrating – it reeks of a sort of unreflective technophobia. What part of processing makes food bad? How does mere contact with a machine turn food from healthy to unhealthy? What food counts as “processed” or “not processed”? Is ground beef processed, since you grind it? Are scrambled eggs processed, since you scramble them? Is bread processed, since wheat doesn’t grow in loaves? Is water processed, since it goes through water processing facilities? Is the Eucharist processed, even though the processing only changes its metaphysical essence and not its physical properties? Everybody I ask acts like the answers to these questions are obvious, but everyone has different answers, and nobody can tell me their decision procedure.
[…]
But how could that be? If people used to be thin and healthy, we should just be able to do what they were doing! And then that would be the diet that can consistently lose weight and keep it off!
I can only see three ways out of this paradox.
First, conventional wisdom is right about everything. People are fatter today than in the 1800s because they eat too much and exercise too little. They eat too much because they are rich, food is cheap, and food tastes really good. They exercise too little because they’re office workers now instead of farmers. In this model, the reason the efficient market hasn’t found the secret to weight loss is because there’s no secret and weight loss is really hard. It wasn’t hard for your great-grandfather because he had fewer options and so he didn’t need to exercise willpower to avoid the bad ones. The most sophisticated version of this model, so sophisticated that maybe I shouldn’t call it this model at all, is the food reward theory ably defended by Stephan Guyenet (a).
This has a lot going for it, but can’t be quite right. Exercise seems like a red herring; studies of how much people eat, exercise, and gain weight have shown (a) that dietary changes explain more than 100% of weight gain over the past 30-40 years – probably we are exercising a little more. And there was really tasty food in 1800s America and 1970s France, so how come people didn’t overindulge in that? How does it explain all the weird results like lab animals, pets, and feral rats gaining weight (a)? This probably part of it, but it still feels like something’s missing.
Second, diet is barely related to the obesity epidemic, and it’s being caused by plastics or antibiotics affecting the microbiome or something like that. This is another thing where I would have expected people to notice, but I definitely don’t want to dismiss it prematurely.
Third, it’s a ratchet. Departing from the ways of our ancestors (or great-grandparents) can make you obese, but returning to their ways cannot make you thin again. A bad diet (whatever that is) shifts your weight set point up, but a good diet does not shift it back down, at least not in a reasonable amount of time. It just prevents further damage.
This contradicts the evidence from some people who do manage to lose weight, including some people who manage to lose a lot of weight and keep it off. I think the theory would have to be that different people’s set points are differently malleable, and that some people are obese because their set point is set to obese, and other people barely have a set point and are mostly operating on calories-in-calories-out. If this seems a little too convenient an assumption, keep in mind this is how lots of other set points work – some people will gain tolerance to certain drugs almost instantly, and other people will never get it at all.
Overall I am ending this research more confused than when I started it. I think the most likely dietary change I make is to try to avoid foods with soybean, corn, or safflower oil, since this is probably a good stand-in for “foods processed enough that they count as processed foods and you should avoid them”. I don’t think the evidence is good for avoiding fish oil and olive oil, and there’s enough evidence from elsewhere that these foods are healthy that I’m going to keep trying to eat them. I don’t think the evidence is good for saturated fats being especially good, and there seems to be at least equally strong evidence that they’re bad, so although I’m not going to work too hard to avoid them I’m definitely not going to optimize my diet for getting as many of them as possible.