(in before translation) I bet she's talking down about the lunch he's eating.
Yup. Mainly, she seems to be commenting on how his main lunch is often caloriemate and he should change it up a bit. Going by the next page, she also suggests making a more healthy lunch for him.
...You heard what those guys were talking about, didn't you?Really, you don't hafta worry about it! ...I said it's fine!...Anyway,Apple...Oh, okay...Cream Bread...You can't afford anything else?I only ever see you eatin' Calorie Mate. Don't you get tired of them?
