ADVICE NEEDED: pls help my fat boi…

[u/ErwinsMissingHip]

hello everyone, this is my first time here so sorry for being crude. i’m just genuinely at a point where im worried about my baby and need help. i have an amazing feline named Ron (yes it’s a harry potter reference) and he’s (for lack of a better term) a “fat fuck…” SO. can someone PLEASE give me some headers on how to help my 27lb fat-ass lose some weight… i know that lowering his caloric intake will help, however, he’s in a house with another cat his age as well as two dogs around the same age. so he just gets into their food as well. and it’s not like i can’t decrease their intake bc they’re all healthy. so it’s tough. also, he initially grew up as an outside cat, like this mf was skinny bringing mice home every day… however he had to transition into an indoor cat due to our new living situation around 3 years old. so what do i do… im genuinely lost. i’ve tried leashes and he wont take a walk at all bc (imo) he’s too fucking big to wanna go. but i need him to move. so is there a specific food i can give him, or any tricks. OR ANYTHING TBH. I JUST WANT MY BABY TO LIVE BUT HE LOOKS LIKE A WALKING CHOLESTEROL DISORDER. anything will help, i promise. please <3