I’m not quite sure, maybe I’m making this one up because I can’t really remember much more, but wasn’t there an episode when cartman tries to eat healthy food and then something bad happens to him. Like he’s getting an allergic reaction or just sick. Then someone, maybe a doctor, tells him and his mom that he can only eat fastfood because his body got used to it. There might be a chance that something like that happened in another TV show. Anyway, thanks for trying to help 😅
You might be thinking about “tsst” which was the episode with Cesar Milan. Another early one was when he went to fat camp and sold other kids candy bars, but I forget the episode name. In the episode where the KFC becomes a weed dispensary, Cartman has withdrawl from not eating the chicken in a while. Other than that, I don’t think there’s any episode where he eats healthier than usual. You may be thinking about another show
I believe it’s “Let them eat goo”, where Cartman gets heart attacks after losing his junk food. S23 ep4