:argh: Oh no, HE. Don't despair and don't throw in the towel. You have done so well.
What you have experienced happens to most dieters, and it's something with which I am all too familiar. I have been good and my weight doesn't go down and sometimes goes up. However, when I think back, I realise I haven't been perfect on all days and those days have caught up with me. I am in the same position as you right now and I know how frustrating this and how easy it is say "Sod it", and then pig out on something.
I know it is no consolation to you to say that you didn't put on weight every single week of your life pre-diet, and you can't expect it to come off every week, and sometimes it will go up, but it's true. Hang in there and follow the WI regime faithfully and you will be rewarded.
When I go out to eat, I tell myself "This is not the last meal you'll ever eat Julie", and I try to stick to plan and only have one plate of food at a buffet, just as if I was eating at home. In the past I would have always tried to get my money's worth at buffets. That's why I am fat. Even if food isn't fried or covered in creamy sauces, batter, doughy or sweet, etc it still contains calories. I'm the person who would have piled up my plate several times and drunk diet coke because I am "watching my weight". The only person I was fooling was myself.
Don't deny yourself syns, just stick to the plan and I am sure you will see that during the month of February, overall you'll have an excellent weight loss.
Remember how far you've already come, and remember the reason why you want to lose weight. You are not just doing it for you, you are doing for your family. Put yesterday's weigh in behind you. You know you can and will lose weight, but it's a marathon and there are always a few hiccups on the way.