What size do you wear? If you’re a Hollywood star like Christina Hendricks, Juliana Margulies or Amy Adams, your stylist probably just grabs a size zero. Welcome to vanity sizing.

According to the Hollywood Reporter, where writer Merle Ginsberg delved into the convoluted world of dress sizes, designers like Donna Karan and Lanvin cut their clothes larger so that a size zero is really an American size four, and so on. This is great for a consumer’s ego, especially if they are a product of the Hollywood machine and conditioned to think they must be the smallest person alive. Also, if they do fit into a “larger size” like a 6 or an 8, they might break into a fit of crying. Don’t laugh, this is a thing. Besides, all of these tiny sizes are relatively new to stateside fashion.

The fact is, 15 years ago, size zero and 2 did not exist in American clothes. "They are really a new precept," acknowledges Neiman Marcus fashion director Ken Downing. You can thank American designer Nicole Miller, who is unofficially credited with inventing the size zero: "One year, our sales manager wanted to size the clothes bigger and we started calling the size 8s a 6," she recalls. "Then the result of that was losing the smaller customer, so we had to add the zero. We also occasionally made some 00s."

There used to be standard sizing, but now it’s a bit of a free-for-all, with clothing cuts depending mostly on the company making the clothes. The Hollywood Reporter cites Nicole Miller as a vanity sizing culprit but we saw Balenciaga designer Nicolas Ghesquière as another proponent of size zero back in 2012. Earlier this year, J.Crew's introduction of size 000, otherwise known as pants for your pinkie finger, sparked a discussion about how insulting vanity sizing is because of this golden rule:

"Some years ago, designers and brands figured out that the smaller the size that fits, the more likely a shopper is to buy it," explains JoAndrea Hoegg, a professor of marketing and behavioral science at the University of British Columbia. "That's when the numbers started going down. It is strategic.”

And kind of nuts. How are consumers supposed to shop online if all of the sizes are who knows what and you can't physically try pieces on your body? What happens when a customer buys their true size and is aghast at its number? How about sizes shouldn't determine how a person feels about themselves?

Still, it's too late for change because “Vanity sizing has been a time-honored tradition!” says Elizabeth Stewart, stylist to stars like Jessica Chastain and Julia Roberts. But Stewart keeps a tailor on hand because you can't trust anyone.

The moral of the vanity sizing story? Find the brand that fits your body and stick with it.

Image via Getty.