Optimal nutrition keeps your dog in good fit and helps to prevent various illnesses caused by malnutrition or overweight. Constant intake of too many calories can ultimately fatten the dog, but on the other hand, if the dog's food consists too little energy, it may cause the dog to lose weight and suffer from health issues.
It's always good check the manufacturer's feeding table as a guide for your dog's nutrition. The optimal weight of a dog can easily be checked by touching the dog's side of the chest - you should be able to feel its ribs with your fingers. Overweight is a severe health issue with today's dogs as it puts the dog's joints and heart under unnecessary stress and can also cause many other health problems. You are able to calculate the exact energy need of your dog with for example these simple step-by-step guides: