For my cat, it was corn, lack of fat, and dry food that caused dandruff. It's also the dry skin season. I'd avoid the weight-loss foods (not enough fat, and may make dandruff worse) and try reducing the dry food and adding more canned to see if that helps first. I can't even tell you the difference in my cat's coat and skin after going to all-canned. I have a friend who has one cat that was a compulsive groomer (to the point of huge bald spots), and his problems completely went away after a diet switch to inexpensive canned and Wellness dry (his vet is completely amazed by the difference, they'd all assumed that he was a head case...as it turned out, he was just itchy, poor guy).