The main issue with Michelle Obama's lunch program was two fold:
1. it limited calories per meal allowed
2. it was warped and twisted in the making when things like pizza were allowed to be considered a vegetable due to it having tomato sauce(the political history of the tomato is crazy), making a much smaller quantity of food max out the calorie count, leaving kids super hungry before school was out.
If anyone wants to actually nail down the problem with all of this, they should look at congress and special interests. Michelle's program would have severely, albeit temporarily, harmed companies like Sysco and Schwans. Iirc, Schwans is the one that pushed for the pizza bullshit categorization and was given it because of how large of a campaign donor it was(I think it was to Klobuchar, but I could be wrong as my memory sucks).