50 years ago, today's size 00 was an 8. This viral post shows why vanity sizing must end.

Deena Shoemaker was going through her closet when she realized something odd: She had several pairs of pants in drastically different sizes.

It wasn't that she had gained or lost a lot of weight recently. Despite the varying sizes on the labels, each pair of pants fit her exactly the same. Shoemaker is simply a victim of something that plagues millions of people around the world: arbitrary clothing sizes. Some brands are "true to size" while others "run small" or "run large." Still others use "vanity sizing" like double- or triple-zero to make sizes seem smaller than they are.

Finding six pairs of pants that fit her the same in a range of sizes from 5 to 12 opened her eyes to just how ridiculous our clothing size system truly is. And as a mentor coach at Youth Horizons, a nonprofit organization that supports at-risk kids, Shoemaker knew that teen and tween girls felt her frustration magnified tenfold.

She decided to share photos of herself wearing the pants to show just how absurdly unstandardized clothing sizes are.

She wrote the post as a letter of support to the girls she's worked with over the years, many of whom struggled with body image issues:

"I've have girls sob in my arms and ask me, 'if I were skinnier, would he have stayed?' I've counseled girls who were skipping meals. I've caught some throwing up everything they've just eaten."

She goes on to explain why she's not happy with the sizing discrepancy that exists across clothing brands:

"When you resize a girl's pants from a 9 to a 16 and label it 'plus size', how am I supposed to fight that? ... How do you expect me to convince her that she doesn't need to skip dinner for the next month because her pant size didn't *actually* go up by seven digits?"

Finally, she implored any girls reading the post to recognize that clothing size does not determine their worth as a person:

"My dear beautiful girls, my size 2 girls or my size 18 girls, your size doesn't determine your beauty; your life does."

There's truth to what Shoemaker found in her own closet: Clothing sizes have been jumping all over the place for the better part of a century.

Photo via iStock.

According to a report from Time, over 50 years ago, model Twiggy wore a size 8. Today, writer/comedian Mindy Kaling wears that same size. These two women have two very different body types. What used to be a size 8 is now considered a size 00.

So where did these crazy size fluctuations originate? Simply put, clothing manufacturers thought women would find their actual measurements on clothing unnerving, so they began a practice known as "vanity sizing" to make women's sizes appear smaller. The horrible irony is the same system that was designed to make women feel better about their size is now making them feel frustrated and confused every time they go shopping.

Thankfully, there are people in the fashion world fighting to make clothes shopping a more inclusive, less stressful experience for people with a range of body types.

Melissa McCarthy promoting her brand Seven7. Photo by Paul Conrad/Getty Images.

Companies like ModCloth are doing away with separate plus-size sections in favor of including extended sizes with their main clothing lines because separating larger sizes is a form of fat-shaming. Newer designers like Mallorie Dunn are featuring women of all sizes to model their clothes and show the world they're actually made for anyone to wear. More and more, we're seeing curvy and fat models, actresses, and designers featured in the fashion world.

But we still have a long way to go. No one should feel they have to change their body to fit into clothes — clothes should be designed to fit the beautiful spectrum of body types that exist in the world. Not only that, but clothing should be marked appropriately and practically. Creating new sizes to make customers feel better only makes it seem as though some body types should be hidden or ashamed to be seen.

As long as vanity sizing exists, young girls who are just growing into themselves and learning to be comfortable with their bodies will face frustration when they go shopping. That's why it's vital for them to have people like Shoemaker on their side telling them it's all just bullshit anyway.

As Shoemaker wrote on Facebook: "Stop believing the social normatives about who and what you should be. You are lovely and you are loved. Just exactly the way you are."