How to Implement MVVM When the Model Type Is Chosen From a View

I have 3 types of models derived from a class FoodItem, and I have a ListBox used to select the current food item type that will be added or edited (I change an Enum on SelectionChanged so I'd know what is the current food item type). I feel it's a bad solution. I am wondering what is the right way to implement this with MVVM.