Here is my take on things - I told friends and family first, once I had a confirmed surgery date. Then after surgery, I told others. Mostly for myself not having to deal with awkward questions... if you loose a lot of weight quickly, sometimes people think you are sick and worry about you. It happened to me before, (another weight loss attempt) and a customer brought me a get well card thinking I had cancer. So - I used facebook to announce to others post surgery, that if they noticed me loosing weight, it was because I was focusing on my health, that I was recovering from a gastric by-pass. The support I got and continue to get is amazing. Be brave - you decide who knows, but consider the positive role model you are.