How to stop dog from eating

My little dog seems to have ballooned in to a chub. I have tried all kinds of methods to help him lose weight but so far nothing has worked. I am tempted to go to the vet and get some appetite suppressants for him. On the plus side he is very active. He does not waddle but runs around and explores our large property like he was when he weighed a lot less. Maybe I shouldn't worry that much, but I do.