I think that just about anyone who starts IP encounters some naysayers, skeptics, and a few of the same mean people who laugh and mock at you whether you're fat or whether you're trying to change. My advice: IGNORE THEM. PERIOD. END OF DISCUSSION.
But...If you have to have that discussion, tell them that you're making an informed decision, that it's your decision, and that it's none of their business. I like to add a few expletives to those statements, but I'll refrain since we're all friends here.
I've lost 110 lbs. on IP. I've averaged 22 lbs. per month. I feel better than I've felt in years. And when I reach my goal I'll be in the best shape of my life and equipped with the tools and knowledge to stay that way. Even if IP is expensive, even if some of the coaches are out there, even if your friends and family don't like it, you can't put a price tag on the importance of the results and the genuine sense of accomplishment that comes from sticking to IP and successfully losing the weight.
Besides, most of the skeptics will come around. And you'll find that you're surrounded by people who are as astounded by your results as you are. I just came from a meeting with our division president. Everytime he sees me (which is about every 6 weeks), he's amazed at the change. And he's not the only one. Hang in there, because you're doing this for you.
And, of course, remember my mantra: The skeptics and naysayers can kiss my steadily shrinking backside!