How to stop cat from eating things outside?

Despite being well fed and healthy, my cat is OBSESSED with eating things he shouldn’t when he goes outside. It’s mostly bits of trees and bushes, but the issue is they’re often getting lodged in his throat which means a trip to the vet to have it removed under anaesthetic.

We’ve tried cutting down the main culprit that he loved to eat, but now he’s moved on to others.

Has anyone experienced this or know how to stop it?

(We’ve tried cat grass and he wasn’t interested in it)