If you check the Guaranteed Analysis on the side of the bag you'll find Eukanuba has a higher amount of crude protein etc than Iams. (29% vice 26% I think). Eukanuba is a brand that I would give to a dog that is very active or an outside dog that can use the extra energy to keep warm. If you feed it to your indoor pet that isn't active it'll just go to fat. That's my opinion. My mongrel, I just switched him to Iams weight control, crude protein 20%, I walk him everyday but he was still putting on the lbs.