If you post about your CrossFit or yoga routine on Facebook, you're probably a narcissist with a deep-seated need for outside validation, a new study says.

A survey from researchers at Brunel University London spotted by Business Insider found that the topics Facebook users choose to post about are influenced by their personality traits.

People who are predisposed to narcissism more frequently post about their achievements -- and that extends to achievements at the gym.

"Narcissists also wrote more status updates about their diet and exercise routine, suggesting that they use Facebook to broadcast the effort they put into their physical appearance," the researchers wrote.

Those kinds of posts also tend to get more likes, feeding the vicious cycle of validation.

On the other hand, people with low self-esteem are more likely to post about their boyfriends or girlfriends.

The data came from 555 Facebook users who completed online surveys about their personality traits.

So next time you see, or post, a CrossFit update, remember the personality traits behind it.