"Eata" is a derogatory term for obese people who are into lolita fashion or cosplay. The word is used as an alternative to the phrase "Ita" which in the lolita and cosplay community is used as a derogatory term for wanna-be lolitas, while the term "Eata" applies to any obese cosplayer or lolita regardless of their outfit.
"This girl is too fat to dress up in that coord, she´s such an eata"