Coworkers Peer Pressure

I have severe sugar addiction and I must get off it. My coworkers bring temptation pretty much every day and leave it in the break room to share with everyone, and there is severe social pressure to eat it. They bring pie, cookies, etc. When I say no thanks they tease me and say "wow you're so healthy" and crap like that. I hate it. I'm socially anxious and I have the urge to fit in too even though it's not the best crowd for me. I really have a problem with what to say and sticking to what is right for me, it seems like I don't care about my own wellbeing.