Briseyda Ponce, 17, tweeted some pictures on March 22 of her 8-year-old cousin, Allysson Baires, stopping during their run to eat a sweet treat in Irving, Texas.
Ponce wrote in her tweet: "The girls in her class & her crush Hector called her fat so she told me to take her on my run but mid run she pulls out a snack."
As of March 29, the tweet has more than 43,000 likes.
In an interview with BuzzFeed News, Ponce recalled jogging with her cousin: "I [explained] to her how beauty isn't physical, and if she wants to work out or run it has to because she wants to be healthy, not because of others' opinions about her body. We [laughed] it off."
Allysson quickly got tired from the run, and pulled out her snack.
"I turn around to check on her and she's munching on a Rice Krispie [Treat]," Ponce recalled. "I couldn't stop laughing."
Stephanie McNeal of BuzzFeed News declared: "This is the most relatable thing ever."
Ponce continued: "Instead we just walked around the block talking, trying to make her understand how beautiful she is."
She noted the social media attention: "It's been fun and everyone has been so kind to Allysson."
Ponce said Allysson is a "smart girl," and, "She kind of brushed everything off and forgot about it."
BuzzFeed News noted some of the positive reactions on Twitter:
[A]nd please tell her, she's beautiful just the way she is. Hector's standard may just be blind or whatevu.
[T]ell her I said Hector isn't worth her time anyway & she's beautiful.
She's such a cute girl, she doesn't have to suffer because of a boy told her so!
[T]hat lil baby can keep eatin cause shes perfect.
Mediaite.com noted there were more tweets directed at Hector (but not at the girls who razzed Allysson about her weight):
You tell that lil one to keep on snackin if it makes her happy! Hector can rot!
[O]mfg I love her!! Hector aint worth it!! She is beautiful and there is a better boy 4 her out there.. watch!!!
[S]he is the perfect size tell her to not change for anyone. shes beautiful.
[P]fft! What does Hector know? Stay healthy, be happy, and above all be Allysson (who is awesome) =)
Dana Eisenberg of Mediaite.com proclaimed: "Not all heroes wear capes. In this case, they wear running gear, and this 8-year-old girl has won the Internet and all of our hearts."