Belly Fat and Elusive Causality

Recently a couple of scientific studies like this one have caught the headlines. The studies conclude that people who drink more diet soda tend to gain more weight, especially gut fat, which is the worst.

This is an important and interesting fact, but almost right away people were saying, “diet soda causes belly fat.” While that may be true, that conclusion is not supported by the studies. The studies show exactly one thing: people who drink more diet soda tend to gain more weight. That is all the studies show. There could, for instance, be a fundamental genetic twist that makes diet soda tastier to some people, that also makes them more inclined to gain weight. Sound farfetched? Possibly it is, but the human animal is complicated, and wacky stuff turns out to be true all the time. There are enough alternatives to the conclusion that diet soda causes belly fat retention that we have to pay attention to them.

Brief aside: Here’s my unscientific take on artificial sweeteners. I avoid them, mostly, but not fanatically. I’ll stick with the known health consequences of the foods my organism evolved eating. I am (unscientifically) confident that those fancy chemicals come with a gotcha — even though the beer next to my elbow right now has far more proven negative health consequences. I am fully aware of the dichotomy in my reasoning.

Anyway, as the press picks up on the story of diet fatness, journalists flip through their electro-rolodexes to S-for-Scientist to find someone credible willing to comment on the story. On the record, respected people speculate on how diet soda and fat could be linked. Perhaps people stop associating sweet tastes with feeling full, one says. Another mentions gut bacteria in rats, and so forth. The press is (generally) careful to present these speculations for what they are.

Then those honest speculations hit Facebook as full-blown fact, and some asshole writes a book selling the shit from Facebook back to the same wide-eyed consumers, and you have another thing everyone knows that may not be true. That person will make a bunch of money, get on talk shows, and…

Hang on a sec, I have a book to write. I think I’ll call it “The Sugar-Free Plague: How Artificial Sweeteners are Destroying Everything You Love”. I probably need a sub-subtitle about big corporations and the government.

This cycle happens all the time, especially in the health fields. Any time you read “X boosts your immune system” you’re probably reading bullshit, or at the very least unproven wish fulfillment. How about this from Harvard Health:

For now, there are no scientifically proven direct links between lifestyle and enhanced immune function.

That doesn’t mean there aren’t any, hell, that would be a crazy proposition. But the thing is, out of the dozens (hundreds? thousands?) of purported immune-boosters, only a relative handful will ever prove to be effective. Overall, “do healthy things” is the advice Harvard gives. Vitamin C, the one everyone knows helps the immune system? Jury’s still out — direct evidence has been elusive, and unfortunately there’s a lot of bad science surrounding this critical nutrient.

The good news is that there’s a lot of good science focussed on this stuff now, and the folks in the labs have tools now that would make Watson and Crick green with envy.

Back to the original theme: There is an entire category of scientific study devoted to finding correlations. Diet soda and belly fat have been shown to be correlated. That’s important, but primarily as a guide to future research. It doesn’t mean that if you switch back to regular Dr. Pepper you’re going to lose weight. Far from it. It does mean that physiologists and psychopharmacologists have a very interesting fact to explain. And when they do, it will help a lot of people.

The correlation studies get the headlines. By the time the nitty-gritty details are worked out, finding causality in the correlation, we’ve already moved on to the next wide-eyed incredulous breakthrough, published first on Twitter.

2

Leave a Reply

Your email address will not be published. Required fields are marked *