Never tried it, but I'm sure if you're doing portions correctly, Fido could lose weight on it.
I believe the fat content is around 15% minimum. Protein is a bit high at 38%. Ash is 8%.
I would think you could do better with Annamaet Lean if you can get it. Lots of people have had luck with Wellness Core Reduced Fat as well.
But I think it's more about reducing portions and getting more exercise. You can use green beans as a 'filler up' to make his tummy feel more full.