Superboy # 24 (Source DC Wikia)

7. That time Superboy got all fat and stuff

So, in the Silver Age, DC had a thing for producing issues in which all their characters got super fat. There’s that issue of the Flash where he gets fat, there’s an issue of Superman where the same happens, and then there’s this issue of Superboy.

In the issue, Superboy, who has been away for two weeks, returns to Smallville, only to discover something shocking! All the students have become super fat for no reason, including Clark’s sweetheart Lana Lang. The next day, Superboy swells up like a balloon, causing Lana to get suspicious, because if Clark is fat and Superboy is fat, then CLARK MUST BE SUPERBOY! Superboy eventually discovers that the entire town has been drinking milk tainted with growth formula, thanks to some stupid cows who ate tainted crops. Superboy fixes the problem and (say it with me now) tricks Lana into doubting that he and Clark are the same person.

OH! Totally forgot, there’s also an issue of Brave & the Bold in which Batman gets real fat. ADD IT TO THE LIST!!!