When I adopted my girls in March one of them was on Science Diet food already so I kept her on it (the sensitive stomach stuff)...but after doing research here and speaking with a colleague who REALLY researched this stuff I GRADUALLY (by mixing and doing all the recommended steps so it wasn't a shock to the system) switched her to a food that was "technically" more nutritional however after a little bit of time I noticed that she began spitting up (not full fledged vomitting but still she would "reject" enough of the food that I began to wonder so....I switched her back and she's not had any issues so...I think the lesson learned is that it also depends on the kitty cat. My last cat lived to be 19years and I knew less about cats when I got her so didn't think to "research nutrition"....and she lived her whole life on 9 lives!!!