I'm not a very private person, so I've told everyone. People have their stuff to say, and I accept that. Most that discourage do so out of fear of complications or losing me, so I am OK with that. They care and are nervous about things not going well. I have one girl I've worked with for years, and I know she is not supportive, but I told her anyway. It's not like she won't notice the weight come off. I figured she would speak her opinion before or after anyway. Might as well get it outta the way!
I can understand not wanting to tell people though. Everyone has their opinion. A very strong opinion once they find out I'm going to Mexico. It's up to your comfort though. But you know you are going to have to come up with something when the weight starts magically dropping off. Best to you!