Should a school be allowed to criticize my childs lunch?

My 13 year old is extremely healthly and in shape. She always has a healthy breakfast and dinner but after years of me making her lunch I told her she can make her own. Here is her typical lunch..Ham and cheddar hot pocket,mini can of soda, chips,and a cupcake. It vary sometimes, but I figure its not a big deal. But I was upset when the principal called me saying she needs a to have healthy options. My daughter is a straight A student and is on 3 sports teams, why is he making a big deal of this