Normally my response to questions regarding weight loss mention lowering carbohydrates, and feeding a food with more meat/animal-based proteins, based on the fact that a dog’s system is designed for digesting animal-based proteins moreso than carbs.
However, you’re feeding a food that I’d normally think was good. So perhaps we need to take another step and look at the calorie content of the food, along with possibly adding a supplement. What you can do is try the Pacifica from Acana, which is the sister brand of Orijen, as both are made by Champion Pet Foods out of Canada. The Pacifica is 421 kcal/cup, where as 6 Fish is 480 kcal/cup.
You can also try adding pumpkin or green beans, and cut back on the food a bit. The pumpkin and green beans should add minimal calories, without any added, but will “bulk up” the feeding. Now, you don’t want to cut back on too much food, as you still want to give your pup enough of the vitamins and minerals that a full diet provides.
