Unfortunately when your co workers start seeing how great you will look and how much weight your down there will be rumors and questions raised.. Take it from someone who works with adjudicated youth and about 200 employees. I've heard it all from my "skinny" "co-workers" and they really are curious, inquisitive only because they care about my health and get along very well together. But, working with detention centers I am the largest employee at the company. The only advice I can give is to either "hide it" and state you've been on strict diet- which is partially true; or, be blunt- "I had surgery, and dont wish to talk about it any further and ask they respect your wishes."
I have already gotten into very heated discussions about "taking the easy way out"- EVERYONE here knows WE HAVE NOT TAKEN THE EASY WAY! We have chosen a new lifestyle after exhausting everything else. I have also had the very inquisitive employees who want to know more about the procedure, etc. I simply say I had a lifestyle change please respect that and leave it alone. I dont want to get into a long story with everyone as to what i did, how i did it, etc.
I know not much help... But the best I can give.