I'm not really doing weight loss FOR IOA/US, but I am doing weight loss in part motivated by our upcoming trip to IOA/US. I'm a no-fad, just-do-what-you-need-to-do kind-of person, so I'm not following any particular diet and I didn't join a gym or anything. In the past 2 1/2 months, I've lost about 18 pounds by making better food choices (single serving of cottage cheese for breakfast, anyone?), becoming aware of calorie counts (trying to roughly come in at 1200-1300 a day), eating smaller portions (packing my own lunch everyday did wonders!), adding LOTS of unsweetened iced green tea to my diet (haven't had one sip of any soda all summer), and walking more (I usually fit in at least 1 1/2 hour a day, usually divided into three stints - early morning, lunchtime, and before bed). I'd love to lose 15 more pounds but would be happy with losing 10 more.
On the list of DIS discussion topics, there is one called WISH that is a community of folks losing weight, changing their lifestyle habits, etc. If you end up joining their group, they even have virtual weekly "check-ins". I didn't join because instead of taking the time to carefully track all my info, I'd rather be out walking!

It's great, though, for those looking for a bit more support.
It can be hard though. DH is running out and just asked if I wanted him to bring me back some food from McDonald's. <sigh> Um, no thanks, honey, but thanks for asking.
