Hi Clair,
Sorry to hear about your troubles

I hope everything works out okay for you!
As well as taking the xenical I go out for a 30-40 min walk at least 5 days a week. The exercise bit is just as important but walking is a relatively easy way to do it.
I'd also be thrilled with a size 16. I jumped the gun a bit today and bought a pair of size 18 tracky bottoms. Bit tight round the tum though.