So, what to do then? Well, you talk about these coworkers in a manner that seems to indicate you see them as friends or at least that you value a positive relationship. Additionally, it sounds as if there is one individual at the center of it all who continues to make comments. Why don't you approach this person individually share that the comments are bothering you and ask how you guys can resolve this? If you let him know that you value having a positive working relationship or friendship with him and ask him to respect your wishes to avoid subjects or attempts at humor that could be misinterpreted, then do you think he would respond favorably?
I did already indicate this to all of those who do this (it's not just 1 guy, it's most of the fat guys). I told them clearly after one of their japes turned to yet another round of "bashing the preachy guy" that if they didn't want to talk about it, they shouldn't make fun of my new eating habits.
It didn't end it. Either they don't get it, or the "insulting the preachy guy" is part of the jape made to piss me off. In the end though, I'm the one staying calm and answering objectively.
And again, I know how I can seem on Macrumors. Don't worry, in real life it's not so, I know how to keep my temper in check be stay polite to people, especially those I frequent on a regular basis and have actual relationships with. I don't need to maintain relationships here so I tend to have a more direct approach in my commenting (just calling it like I see it I always say). You have to admit some posters here went straight to attacking me directly, ignoring factual information I have provided (not even quoting it and putting it into question, just outright ignoring it).