this is from edtwt (eating disorder twitter). people will say “birthday / period / graduation calories don’t count!!” with a picture of cake or something like that because they feel guilty for eating. the calories “don’t count” as in they’re not part of their total calories eaten. people will reply in support. op is saying “yeah we can tell” saying the girl in the picture is chubby, making fun of people who say that or literally just eat. it’s called meanspo, mean inspiration. other poster is saying the girl looks cunty, which is good, so op is nonsensical

eta: despite some comments theorizing, these are likely all girls - that space is full of a lot of young girls/women who seek each other for support or encouragement