After seeing Avengers: Endgame a few months ago, I was pleased beyond words to learn that I have the body of a god — and not just any god. I have the body of Thor, the god of thunder, as played by the ultra-ripped, super-jacked, mega-shredded Chris Hemsworth.

Well, Chris Hemsworth wearing a 90-pound prosthetic gut.

It’s part comic relief and part exploration of how people deal with serious trauma, and it was the subject of endless chatter on YouTube clickbait videos discussing fat-shaming and depression and PTSD and the like.

I find it an interesting and useful way to think about Thor’s character arc, and I look forward to seeing what they do with him in future films like the likely Guardians of the Galaxy 3 movie that we simply must have now that they have added him to the team. But I think there’s an important and overlooked lesson about how we think about economic progress and its causes.

So here’s the question: why did Thor get fat? There’s an easy and not-so-informative explanation, which is that he doesn’t seem to have gotten much exercise in between long bouts of cable TV and Fortnite with his friends Miek and Korg and has switched to a diet that looks like it consists mostly of beer, pizza, and junk food. In the words of Rocket Raccoon, Thor “look(s) like melted ice cream.” 

When Thor asks the team if they know what is running through his veins, War Machine (James Rhodes, played by Don Cheadle) replies, “Cheez Whiz.” At another point in the movie, Thor gets to talk to his mother Frigga, who questions his wardrobe choice (sweatpants and a loose-fitting hoodie) and, after a heart-to-heart about Thor’s battle with depression, exhorts him to “try eating a salad.”

The prescription, such as it is, is easy: Thor needs to eat less, drink less, and move more. Perhaps a more sophisticated approach would have us say, “He needs to eat fewer simple carbohydrates, cut back on the booze, and instead rely on a diet high in fat and protein.” Follow your mother’s advice too, and try eating a salad.

This is good advice, but it would kind of miss the point. Thor’s (lousy) diet and (apparently nonexistent) exercise regimen are proximate causes, just like there are proximate causes of economic growth: natural resources, labor, tools, skills, and new ideas. A country looking to increase its output would do well to invest in more of each. More inputs, more output. It’s simple — and in the Solow growth model, we can move to higher levels of steady-state output by increasing our investments in any of these.

These are only proximate causes, however. “Thor got fat because he ate and drank too much and spent too much time sitting around playing video games and watching TV” is obvious and probably not all that helpful. Thor probably knows this, and his descent into less-than-healthy habits has been driven by something a lot deeper — specifically, the depression resulting from his failure in combat with Thanos. The more important question is “Why did Thor descend into such bad habits?”

The same goes for exhortations for countries to save more or invest more in education. Trillions of dollars of foreign aid targeted toward capital accumulation and education didn’t do much to lift the world’s poorest out of extreme poverty because there are much more fundamental institutional, cultural, and rhetorical problems explaining why these societies aren’t investing in physical and human capital, making wise use of natural resources, or innovating widely and rapidly.

Before I conclude, I want to be absolutely clear: this doesn’t excuse Thor’s actions or let him off the hook for their consequences. He has agency, after all, even in the face of severe mental and emotional trauma. However, a bit of digging might help us understand why good advice — eat less, drink less, and move more — doesn’t seem to stick.

Explaining Thor’s slovenly despair as the product of pizza, TV, and alcohol per se ignores root causes that might be a lot harder to change or dislodge. Dealing with those root causes is a lot harder than just saying, “Eat and drink less, and move more,” just as it’s a lot harder to simply say that saving more and sending more kids to school is a way to help societies get richer.