No support

In my experience so far, the lack of support from some people is because they don't know how to deal with the uncertainty following the surgery.  They can be worried about the safety of the procedure itself, concerned about how your relationship with them may change once you are thin (and a "new" person, maybe with different requirements about what you expect from people in your relationships) or even just used to being the "thin one" and unsure how the dynamic will change once you lose weight.  I've had people that have bugged me for years abou my weight be discouraging (or at the very least, not encouraging) when I've told them that I am having surgery.  It's a bummer, but isn't going to change my plan at all. 

You know the right thing to do for yourself.  People can either get on board or get the heck off the tarmac!