Having a kid that plays high school football, I know the school lunches don’t begin to cover the calories burned working out daily.
My daughter is a competitive swimmer, she swims 5,000-7,000 yards a day, eats around 5000-6000 calories of food a day. School lunches have never sated her appetite, so she packs a lunch. She doesn't have an ounce of fat on her, but she would starve if we didn't send lunch to school with her.
Shoot, when I played high school football I would eat two Wendy's triples w/ cheese, fries and a frosty for lunch. Go to practice and come home and drink 1/2 gallon of milk. Never broke 200 pounds on my 73 inch frame.