But now imagine that instead of talking about why we get fat, we’re talking about a different system entirely. This kind of gedanken (thought) experiment is always a good way to examine the viability of your assumptions about any particular problem. Say instead of talking about why fat tissue accumulates too much energy, we want to know why a particular restaurant gets so crowded. Now the energy we’re talking about is contained in entire people rather than just the fat in their fat tissue. Ten people contain so much energy; eleven people contain more, etc.. So what we want to know is why this restaurant is crowded and so over-stuffed with energy (i.e., people) and maybe why some other restaurant down the block has remained relatively empty — lean.
If you asked me this question — why did this restaurant get crowded? — and I said, well, the restaurant got crowded (it got overstuffed with energy) because more people entered the restaurant than left it, you’d probably think I was being a wise guy or an idiot. (If I worked for the World Health Organization, I’d tell you that “the fundamental cause of the crowded restaurant is an energy imbalance between people entering on one hand, and people exiting on the other hand.”) Of course, more people entered than left, you’d say. That’s obvious. But why?And, in fact, saying that a restaurant gets crowded because more people are entering than leaving it is redundant –saying the same thing in two different ways – and so meaningless.
Now, borrowing the logic of the conventional wisdom of obesity, I want to clarify this point. So I say, listen, those restaurants that have more people enter them then leave them will become more crowded. There’s no getting around the laws of thermodynamics. You’d still say, yes, but so what? Or at least I hope you would, because I still haven’t given you any causal information. I’m just repeating the obvious.
This is what happens when the laws of physics (thermodynamics) are used to defend the belief that overeating makes us fat. Thermodynamics tells us that if we get fatter and heavier, more energy enters our body than leaves it. Overeating means we’re consuming more energy than we’re expending. It’s saying the same thing in a different way. (In 1954, the soon-to-be-famous — and often misguided, although not in this case — nutritionist Jean Mayer said that to explain obesity by overeating was about as meaningful as explaining alcoholism by overdrinking, and merely reaffirmed, quite unnecessarily, the fact that the person saying it believed in the laws of thermodynamics.) Neither happens to answer the question why. Why do we take in more energy than we expend? Why do we get fatter?
Answering the “why” question speaks to actual causes. In the restaurant analogy, okay, maybe this restaurant has particularly great food, or it’s happy hour; the drinks are cheap. Maybe it’s pouring outside so a lot of people ran into the restaurant to stay dry. Maybe every other restaurant in the neighborhood, including our lean restaurant down the block, was recently closed by the local health bureau and this is the only one that didn’t have cockroaches in the kitchen and so remained open. Maybe it’s in the theater district and the shows just got out and now every restaurant in the neighborhood is packed with the post-theater crowd. Maybe the word has spread that Brad Pitt and Angelina Jolie frequent this restaurant regularly, or Oprah, and this attracted a crowd hoping for a glimpse of celebrity.
All these would be valid answers to the question we asked. Some speak to the conditions inside the restaurant (the quality of the food, the price of the drinks, celebrity customers); some speak to conditions immediately outside (a rain storm, no competition, the theater schedule). They all provide the causal information we’re seeking. They answer the “why” question. That more people are entering than leaving doesn’t. It’s what logicians call “vacuously” true. It’s true, but meaningless. It tells us nothing. And the same is true of overeating as an explanation for why we get fat. If we got fat, we had to overeat. That’s always true; it’s obvious, and it tells us nothing about why we got fat, or why one person got fat and another didn’t.
Some obesity experts are intuitively aware of this problem, which is why they’ll say, as the National Institutes of Health does on its website, that “Obesity occurs when a person consumes more calories from food than he or she burns.” By using the word occurs, they’re not actually saying that overeating is the cause, only a necessary condition. (It’s like saying “a crowded restaurant occurs when more people enter than leave.”) They’re just saying that when one thing happened – obesity –the other thing also happened – consuming more calories from food than we expend. And now it’s up to us to say, okay, so what? Aren’t you going to tell us why obesity occurs? Rather than tell us what else happens when it does occur.
As for the great majority of experts who say (and apparently believe) that we get fat because we overeat or we get fat as a result of overeating, they’re the ones making the junior-high-school-science-class mistake: they’re taking a law of nature that says absolutely nothing about why we get fat and assuming it says all that needs to be said. This was a common error in the first half of the 20th century. It’s become ubiquitous since.
If the experts had ever been open to a little skeptical thinking from others or had they been appropriately skeptical themselves, this might never have happened. What’s been needed (and still is) was for someone (a reasonably smart 14-year-old would suffice) to ask the obvious questions and then insist on intelligent answers. Here’s how such a dialog might go:
The experts: Obesity is caused by over-eating, by consuming more calories than are expended. There’s no getting around the first law of thermodynamics.
Us: But all that law says is that if somebody gets fat, they have to consume more calories then they expend. So why do they do that?
The experts: Because they do.
Us: That’s not a good enough answer.
The experts: Well, maybe they can’t help themselves.
Us: Why can’t they help themselves?
The experts: Because they can’t.
Us: That’s not a good enough answer either.
The experts: Because the food industry makes them do it. There’s so much good food around and it’s so tasty, they can’t help but eat it.
Us: But obviously some of us can, because we don’t all get fat. Why is it only some people can’t help themselves?
The experts: Because they can’t.
Us: Try again.
The experts: Well, it’s complicated.
Us: What do you mean complicated? We thought it was easy. Just this eating-too-much, exercising-too-little, calories-in-calories-out, thermodynamics thing.
The experts: Okay, how about this? [Now quoting from an NIH report published in 2000.] “Obesity is a complex, multifactorial chronic disease that develops from an interaction of genotype and the environment. Our understanding of how and why obesity develops is incomplete, but involves the integration of social, behavioral, cultural, physiological, metabolic and genetic factors.”
Us: So what do all those have to do with eating too much and the laws of thermodynamics?
Experts: They contribute to making fat people overeat.
Us: How do they do that?
The experts: We don’t know. It’s complicated.
Us: Then maybe there’s another way to look at it. Maybe when we get fat it’s because those physiological, metabolic and genetic factors you mentioned are dysregulating our fat tissue, driving it to accumulate too much fat, and that’s why we eat so much and appear — to you anyway — to be kind of lazy. We’re compensating for the loss of calories into our fat.
The experts: Yeah, well, maybe. Your guess is as good as ours.
