No you can't. The thing is I did read that you can use some breathing exercises to tighten your stomach muscles so that it may help appear to have a smaller waist. The method is fairly simple in doing a crunch and exhaling all the air out of your lungs and crunching/exhaling the last of the air in a quick moment.
So it would be something like exhale/slight crunch... when your lungs are almost completely empty, exhale the last of the air forcefully/crunch as much as you can. Now I don't know if that works but it doesn't hurt to try it. Of course I haven't tried doing it in a while