The worst that could happen is some people wondering why you are doing that. Just tell them you got bored by your old self. Also you probably already sound a bit fake, because as you say it yourself: you are.
You can either do it gradually or wait until there is a two-week break or something, and prepare yourself, and be like that when you come back. I've figured that changes are way easier to show when you haven't seen people for a few weeks. Worked everytime for me - when I had to start to wear glasses, got new haircuts, etc.
And seriously, people could care less about what you do. They'll make you one or two remarks on the first days, will discuss about how you changed at lunch, and then they will have something else to talk about.
Hey, think about it. Some people might be talking about you behind your back to say how you positively changed. Isn't that awesome?