I would say to tell them that you need time to get adjusted to your new plan and just can't go with them at this time. At some point you may be able to hang out and resist temptation but that takes a minute. I went out Friday night and only drank water the whole night. The bartender jokingly told me to get out since I wasn't doing rounds with my friends. They likely won't understand but you have to be willing to sacrifice right now.

Here's where you have to know yourself and understand what you CAN and CAN;T handle. I avoided going out as much as possible. I also talked with my doctor to learn strategies for when I do go out. Having a specially made salad (no cheese, no croutons, no carrots) and a small piece of grilled chicken breast with a side of steamed veggies. For drinking, get water with lemon- so you're still getting some flavor and the lemon (or lime) gives the appearance of a drink. Be honest with those close to you. You're working hard to improve your health and you'd really appreciate their assistance. Avoid the places where temptations are the greatest (work break rooms) or whatever. It's tough, but very soon you'll be thanking yourself- a LOT! Good luck!