I agree: hearing it in theory you do get the 3-heads look but when people actually see me on it and see me going through it, they'll both be curious and also say they can't imagine going that long without food. Everyone at work is amazed, but I tell them it's much easier than it looks: the lemonade actually makes you not hungry. But I think the big kicker that makes them not freak out is when I'm several days in and they see that I'm still normal: energetic, aware, doing ok and not hungry. Then they seem to shift view since they can see it's not killing me.
Plus you'll be surprised when you find there are some people open to the idea altogether because their religions or readings have already introduced them to fasting. A lady from work last year mentioned the cleanse to me and I immediately said "I want to try it!" I surprised her when the next week I had researched it and started my first cleanse! :-)