I'm Really trying to make this the last time!

I keep reading how people can't loose weight... my challenge isn't as much not being able to loose weight, but rather keeping it off.  What I mean by that, is when I focus on a healthy lifestyle I shed the pounds and the second I stop focusing they come right back.  I honest think I haven't been a the same weight for longer than a week or two... and that's usually because of plateau during my weight loss of my weight gain.

Part of the challenge is that I'm an excessive person - everything I do seems to be in the extreme.  When I'm focused on weight loss, I'm not tempted to deviate and am only interested in healthy eating.  When I'm not focused, it's very typical of me to enjoy a BOX of chocolates and a PINT of icecream on the same evening... and a few cocktails to really make the party :-(

Over the past 14 months I lost 45 lbs and gained 35 lbs - the only good think is that the 45 lbs weight loss took less time than the 35 lbs weight gain... but we all know this is so unhealthy. 

So... I'm going for it what I hope is one last time.  If anyone has any suggestions on how to maintain a weight, I would love to hear from you.  It will take me close to 6 months to get back to my ideal weight and then I need to find a way to keep it off.  So that means I have 6 months to figure out the magical recipe... help!!!