A dog's weight is one factor required to calculate its proper food intake. Other factors include the dog's age, health and daily activity level. When calculating the correct amount of food, it is important to use the dog's ideal weight, especially if the dog is over or underweight.
Another factor in a dog's food intake is its breed. For example, small and toy breeds often have faster metabolisms than their larger counterparts and therefore require more calories relative to their size.
Nutrition is important to consider when feeding a dog. Active and working dogs require specially formulated foods that are higher in protein and fat. Overweight dogs should eat food low in fat and high in fiber.