I have two cats. They are about 1 1/2 & 2 years old. The two year old is getting a little chubby. I used to leave food out 24/7, because the younger one wasn't fat and I didn't want to punish him by giving him less. Because of my living situation, they have about 400 sq ft of living space, so it's difficult to only leave food out for one of them but not the other. Anyways, I have been leaving food out for them for about 6-8 hours a day. Is that long enough? They have unlimited amounts of food at that time. By the way, it's dry food, if that wasnt obvious.