As a single guy, to be honest I don't think I will be telling anyone I date post surgery that I've had WLS. It's not like I'm not telling them I have an std or something that is medically relevant to them.
If I had, say... Laser eye surgery 5 years before we started dating, am I required to tell the person? It doesn't affect them in any way, shape or form.
On the other hand, if they notice scars, or ask why I eat so little, then I'm not gonna lie about it either.