Just switched my kittens food to Innova Cat and Kitten food after having fed them cheap grocery store food?

you should be fine i brought a cat home from my parents after it had been fed grocery store food for like 4 years, and switched her to the innova as well she LOVES it although hated the soft food at first. they will likely eat less because it is more nourishing so it fills them up faster just follow the directions on the package for their age/weight group and they'll be fine. It shouldn't be detrimental at all many cats live to be in their 20s eating grocery store blends their whole lives. but the first thing you will probably notice in them is the change to their coats they will get so nice a shiney from the human quality food.