Hiding columns in a Matrix until toggle is clicked

Hi,
I have created a Matrix report which looks at a Data Warehouse cube that allows users to toggle from the top level to the bottom level in 2 clicks. Having added the fields and groups for the report it adds 2 blank columns to the report which are populated once the toggles are clicked. Is there a way of hiding the 2 columns until the toggle is clicked?

Thanks in advance
Aled