what to tell people besides the fact that you're "water fasting"

Just wondering what you fellow fasters out there tell your fellow friends and family you're doing when you're water fasting. Some cleanse for weight loss, others for detox, some for spiritual reasons etc. But for those of you who don't want to get the strange looks...even from closest family and friends...what do you say to people? I would rather not tell anyone that I'm water fasting...they would get too concerned and think I was trying to starve myself because they just don't understand. But people definitely notice that I'm not taking in any food. I just don't want to worry people, but I want to be able to fast without my anyone worrying about me. Is it better to tell people the truth or keep it to ourselves?