You, my friend, are a healthy person. You don’t need the NYC soda ban to keep you from over-consuming unhealthy, corn-syrupy soda. You don’t get the Big Gulp soda. You don’t get the large. You get the medium.

But what does that actually mean? Do you know?

Probably not. As NPR’s The Salt writes, although people make decisions based on size labels, they don’t really know how much food or drink they’re consuming. University of Michigan Professor Aradhna Krishna proved this (with science!):

In one experiment, she gave people cookies that were labeled either medium or large, and then measured how much they ate.

The catch? The cookies were identical in size.

What happened? You guessed it. People ate more cookies when they were labeled “medium.” Rather than trust what their stomachs were telling them, in other words, people went by the label.

It’s sort of like when McDonald’s tells you their new wraps are “healthy,” because, hey, they’re not a burger. You tend to believe that they are healthy, even though there is the same breaded, fried chicken in it as in a sandwich.

The depressing bit is that we don’t even know we’re being taken in by a “medium” that is actually quite, quite large:

“Just because there’s a different size label attached to the same actual quantity of food, people eat more. But also, [they] think they’ve not eaten as much,” says Krishna.

Basically, Starbucks is the only chain that has the right idea: Call fucking EVERYTHING “large,” using synonyms and if necessary different languages, so people have to actually look at how big the thing they’re buying is relative to other things. That doesn’t address the fact that half of what Starbucks sells is just melted caramel with steamed milk, but it’s a start.