That is good to hear.
I use dog food for mine too mainly because mine refuses salads (Like most blueys). Merrick used to be highly recommended and I loved it because it comes in pate and the ingredients had a lot of fruits and veggies mixed with the meat. Since Purina bought them out, I no longer find that particular formula so that is unfortunate. Blue Buffalo Chicken with Garden Vegetables is a good one. Try to go grain free and stay away from the gravy kind since that carries more water/less meat than the pate ones.
If it picks at its food or eats only what it wants, either reduce the portion or space out the feeding. It is very easy for these lizards to gain the weight but very hard to lose it once it is there.
You can also add snails in their diet which they love as that is what they naturally would eat in the wild. Don't use the ones from the garden as snails are common hosts to parasites. I buy canned snails meant for human consumption and with our seasoning from Amazon. For about $23, I get about 200 large snails. I would not waste money on the reptile brands canned snails. They are tiny, comes in very limited amount and they charge almost $5-6 a can. What a rip off.
Hornworms and black soldier fly larvae would be a great addition to his diet. They are high in calcium and hornworms are easy to chew and hydrates your lizard well. Wax worms are great to help gain weight on skinny lizards. Mulberry farm website always carry sales. I think they still have the buy 2 containers if hornworms get 1 free deal. They always add extra for you.