I am really struggling today...
I feel your pain - days like this suck the big one.
Some good advice from the people on here already - fill up on yummy fruit! I like to smother it in fat free yog mixed with sweetener.
Our SW consultant did something really interesting this year. For about 6 weeks prior to our last pre-Christmas meet on the 22nd she had us passing around a bundle of knitting and each doing a row. She made it a competition between the three classes that she runs, and it got quite fierce - a lot of hard work and interesting patterns went in to that knitting!
Then at the Christmas WI, she got the knitting out, had us all admiring our handiwork... and then she proceeded to unravel it, much to our horror.
She said 'Now remember this feeling, and looks on all of your faces. Think of all the hard work you've put in this year, how pleased you have all been with your progress, but remember...' (still unravelling the knitting) '...how easy it is for the whole thing to come undone. And how much it's not worth it, for the sake of your brain demanding cheap thrills in the form of choco-lard'.
I'm paraphrasing of course, but it was quite an astonishing little demonstration, and it has stayed with me all Christmas.
I hope you manage to see your way through today - I hope we all do - and I know we'll all feel better and stronger for it come tomorrow and the next day when life goes back to normal and we're left facing another year!
Get your hubby/kids to hide the chocs/anything tempting. They'll support you (especially if they know they still get to nom the chocs!)
Good luck
Rx