<prompt> The optimum calories to be provided by proteins should be5-1010-1515-2020-30  <response>: The main source of energy in the diet is carbohydrates derived largely from cereals and provide 50-80 of daily intake. Most families derive 10-12 of energy from proteins. Energy from fats may vary from 5-30.Ref: Park; 23rd ed; Pg 634 