I don't know if the calorie difference would really be worth the fight?? Instead, send in high calorie brownies (I'll go to day care for brownies!!)
I had a sort of similar fight with the middle school. I was told to send in a snack (BECAUSE LUNCH IS LATE!!) and that it had to be less than 100 calories. Really? Why bother? Since my kids have such food allergies, we don't buy snacks, we MAKE em! Well, they told my son he couldn't have his because he couldn't prove they were less than 100 calories. (trail mix .. cashews, raisins, gold raisins, dried cranberries, and allergy friendly choc chips) I made them prove they WERE more than 100 calories.
Have you thought about some nutritional supplement for Becca? Ensure, Pediasure, even Neocate? She needs some calories. What is her weight?
The most embarrassing moment. ever. was when we started a consult with a nutritionist and the first thing she said was, "Your kids are not getting enough calories."