How Much To Feed Your Cat. According to the Animal Medical Center in New York, a healthy, active 8-pound adult cat requires about 30 calories per pound per day. So, the average 8-pound cat requires about 240 calories per day.ypically, dry food contains about 300 calories per cup, and canned food contains about 250 calories in each 6 oz can. (or, 125 per 3-ounce can). Using these counts as a guide, an 8-pound cat would need 4/5 of a cup of dry food or just less than a full 6-oz can (or two 3-ounce cans) of wet food per day.