What to tell your boss about WLS?

specially at the beginning - if it were me - and someone asked me - I told them is a personal; 

"I know you mean well, but I rather not discuss my medical issues at this time. i hope you understand. It is personal". most smart managers - will stop asking...

I work in a small office. And I am the manager.  I also know the people for years. And I had to remind myself not to ask them details about medical issues, doc visit, etc. And if I do I make sure to tell them that I am asking as a friend and not the boss, but that they do not owe me any explanation. 

I had been on so many diets and felt like such a failure with all of them....it was embarrassing.  I felt like I had to tell my boss because I decided to take four weeks off.  I wasn't planning on telling anyone else.  One girl found out and she alerted the entire building...she even told the postman.  I finally told her to stop!  She said she was proud for me but that was not the way I was taking it.....I did not want any judging ....."thought she had surgery...why has she not lost more.....why is she eating that....why is she eating that much....she is just lazy"....I still have problems with the whole thing.....I have been a slow loser....comparative to others...I did not tell but a few family members....most still do not know....did not tell anyone at church....I just didn't want to fail again.I have lost a 100 lbs but it has took me a year....I feel I have been the queen of stalls....but it is ok.....I will get there eventually....in my own time!....I still feel that some people...it is just none of their business!