A balanced diet contains all the needed nutrients and vitamins but does not exceeds them. Everything in the right amount is considered as a balanced diet
For Example:
Protein - milk ,meat, eggs, beans , vegetables
Carbohydrates - potatoes, grains, lentils.
Vitamins and Minerals- water and fruits
Fat - meat, eggs, oils
note- milk is a  balanced diet in itself
       - roughage is necessary (water)
i hope my answer helps you in the best possible way:)!!