Royal Canin is really overpriced for being a lower quality food. Its about as good as Purina. Food brand doesn't make a dog fat though. It how many calories you feed them and how much exercise they get. A typical adult pug only needs about 450-500 calories a day to maintain its weight. The calories per cup should be listed on the dog food bag.

As for better brands, do you live in the US? Its hard to recommend brands if they aren't found in your country. Great brands are Innova Evo, Orijen, Before Grain, and Wellness. If you are looking to go a little cheaper I would suggest Taste of the Wild, unless your dog has any food allergies, or 4Health.