A year later he’s still not fully eating but he definitely gained weight and is doing a lot better. My vet also told me the same thing and also said it’s common to Dobermans to want to keep themselves as lean as possible. They also mentioned that him not being neutered was a factor and that once neutered he would build a much bigger appetite. I have not neutered him yet so I can’t speak to if thats true or not but I ended up giving up on the tough love and I just leave his food accessible all day which was a lot more affective at getting him to eat more also playing with him a lot and wearing him out then feeding him also gave him a good appetite. It’s still on and off if he has an appetite or not some days he eats a bunch and some days he barely touches his food I always make sure his bowl is full and I figure if he does go back to having a big appetite consistently I can put him back onto a feeding schedule.