Hmm, I need to check the code - the file size is not supposed to grow
Basically, the data file is organized in chunks (pages) of data. MT allocates more and more as they are needed. As some data is cleared, those chunks are then flagged as free and re-used before other new ones are allocated. The file never shrinks.
If you for example clear all data right now, you will have almost all pages empty but the file will still be 500 MGB. Well, consolidate basically creates a new file, copies only the used pages, which should result in a much smaller file.