I would ask. When I ate at Sci-Fi in October, I got the appetizer and entree, but by time dessert came, I was fuller than full. My waitress offered to wrap something up for me and I declined - didn't want to carry it around all day. She then offered to get me a milkshake to go as my dessert. Again, I declined as I had a fabulous Milky Way drink (not on drinking plan) and really didn't have room for it.
Cheers!