school lunch is too lean too small

My son always hungury. They only offer 3 types, always one as vegie, sometimes another one very less protain such as cracker+jelly+cheese stick etc.  That leaves only one choice for my son to take some meat and real lunch.

Quantity is not very ample, my son can finish almost the whole meal even in pre-k class, can not imagin he's eating the same lunch up to grade 5.