Help! I'm scared of my own lack of self control :s

I know where you're coming from; I've always had more trouble with "free" food than not-free. So if someone is taking me out to dinner, if it's a buffet--or if I'm over at someone's house and they have a lot of munchies out--I'm more likely to overindulge.

That said, ultimately, the food is always around; as an adult with purchasing ability, we always have access to something that is bad for us. It's not easy, but at the end of the day, we really do have to learn how to say no (or how to limit our intake). No one can control us but ourselves, and we have to make "good" decisions all the darn time. (It's not like ceasing to eat is on option! The food will ALWAYS be around us.)

What I've found has worked for me fairly well--it really helped me over Christmas when I was surrounded by many yummy (and free, lol!) treats, was to consider if eating more of it would make a difference. i.e. Eating the food itself is an extremely transitory feeling. It's gone in an instant. If I think about how super yummy that brownie was the next day, does it make a difference if I had one or if I had ten? Nope, I still just remember that it was a really yummy brownie. In that way, I was able to control my urge to just keep eating. I had ONE really yummy oatmeal shortbread, ONE piece of brownie, etc., and savoured them. (I was far from perfect, but I was really proud of myself. And at the end of the two weeks, I actually registered a loss, albeit a small one, instead of a gain!)

Incidentally, I also found that when I controlled myself like that, I had far less of an urge to eat everything in front of me. (I think of it as the refined carbs getting to me, though that might not actually be what it is. If I eat a ton of them, more than usual, then I WANT a ton of them. Instead, if I just enjoy an extra treat or two, it seems special and doesn't mess up my eating habits.)

I know just saying you need to learn to master it probably isn't hugely constructive, so other things I can suggest:
1) Eat in moderation. Unless the food is your kryponite, plan for a reasonable portion that fits into your daily goal. Otherwise, you're probably more likely to binge on it. BUT, if the food is your kryptonite, and you can't stop eating until you've had the whole giant bag of potato chips or the box of cookies, etc., then consider cutting that one out completely. I gave up chips in the 9th grade for that reason and haven't eaten them since. But pretty much anything else, I'll happily eat in moderation.
2) If you really don't think you can trust yourself and can't do what the poster above suggests about talking to your hosts (you did say it was starting tomorrow), I'd suggest that you lock the food away. Pick a room, move it all in there, and then stay out of that room. (And keep the dog out, obviously.) Out of sight, out of mind?

Best of luck! It takes hard work, but it's totally doable.

Don't even open the food cabinets or pantry if you can lol....avoid like plague

If you can tell them that you really appreciate that they normally buy you nice treats but this time would they not buy anything as you are going to bring your own food. If they have already done so ask them to put it in a cupboard that they know you will never go in whilst you are there. Whats out of sight is out of mind. Good luck and be positive and trust yourself.

You need a therapist.

Out of sight - out mind. Take all the unhealthy food and put it in the veggie drawers and take out all the veggies and put them where you can see them. Also - make a deal with yourself that if you see a trigger food you want - you will do enough jumping jacks, burpees, whatever to burn off the calories to earn it.