It sounds like your cats have simply learned that they can beg for food whenever they see you in the kitchen, and are now doing that whether they are actually hungry or not. Basically, by feeding them whenever they do this, you have been rewarding that behavior, and have actually taught them to do this.
Now, you need to take steps to un-train the behavior; or it will continue. So, firstly; stop rewarding the meowing, don't feed them every time they do it. In fact, feeding them dry food that can sit in the bowl, will help a lot. That way, you know that they can have food if they are actually hungry. Feed them the canned food only once or twice a day, on the schedule you want to establish.
Soon the cats will learn that they are not going to be fed, and will stop yowling for food.
