The current trend, according to my dogs' vet is to mix vegetables with their kibble to help them loose weight. That's just fine, with a little soy sauce mixed in they'll eat it. I tell them it's stir-fry with cat mixed in.
Whatever you do don't feed then canned corn. They liked it but this morning I really needed latex gloves and a dustpan to clean up after them. Just like the scoop law sign.
http://www.dogjaunt.com/files/2011/05/photo-133.jpg