In the well meaning and fun spirit of HN pedantry it was 239lbs in Season 1 Episode 10[0] which aired March 25, 1990. By Season 7 (1995) he was trying to get to 300lbs to be classified as "obese" and get on disability[1].
But, to your point, his quote of "239 pounds! Awwww, I'm a whale. Why was I cursed with this weakness for snack treats?" would be nearly insulting to much of an American audience today and the grotesquely obese Homer portrayed from "King-Size Homer" (at 300lbs) would likely need to be used for that joke today.
But, to your point, his quote of "239 pounds! Awwww, I'm a whale. Why was I cursed with this weakness for snack treats?" would be nearly insulting to much of an American audience today and the grotesquely obese Homer portrayed from "King-Size Homer" (at 300lbs) would likely need to be used for that joke today.
[0] - http://www.simpsonsforever.com/episodes/quotes/quote.php?id=...
[1] - https://en.wikipedia.org/wiki/King-Size_Homer