First, what breed (or mix of breeds) is he?
I once adopted a 6 year old yellow Lab from a family. When I asked how much she was fed, the owner said "my husband just fills their (2 dogs) bowls".
I got her and measured her food, fed I think 1.5 cups twice a day and she lost 10#. She was 80# when I first got her.
I feed my 38# Walker Hound 3/4 cup twice a day.
I think you said he gets 3 cups total a day. Is this actual measuring cups or just a plastic cup you use?
I'd say feed him 1.5 cup twice a day and be aware of not too much other treats.
Good for you for noticing the issue and doing something about it!
Most dogs that are overweight are because their owners do not measure/regulate their food.
---------- Post added at 02:48 AM ---------- Previous post was at 02:31 AM ----------
Forgot to add that a front hook harness is GREAT for helping to stop pulling! Still have to work with the dog but it is a huge help. I have an Easy Walk Harness. It's hard to get a correct fit though, I tried 3 sized and gave up and just got the one that fit the best.
A friend just told me the Easy Walk was one of the first front hook harnesses and now there are better fitting ones. Balance Harness being one of them.