I'd guess both, and my guess is part of the problem is fat people who think diet soda is an alternative to actually dieting. Which seems like the sort of risk compensation the article is talking about.

I tend to consider reality TV to be fake, but I think people like this really do exist: https://www.youtube.com/watch?v=iIAFe7zaCRU

> "Our mom told us when we were younger, if we ate a sugar you drink a diet coke afterwards and it will cancel out the sugar"

> Do you believe that to be true?

> "I did when I was a kid."