I have always had big dogs and definitely recommend feeding them at least twice a day, especially if you have overweight dogs. It is a matter of metabolism - if you feed them smaller meals more often, it will increase their metabolism and aid in weight loss. I would also take a look at the type of food you are feeding them. Some of the bargain dog foods have much more filler and fat content and can cause weight problems. Better foods are richer and dogs actually can be fed less amounts to get the right nutrition. I would recommend talking to your vet and getting recommendations from him/her on what food is best for your furkid.