Tom, I put weight on quickly especially when I have a week off.
I dont know if this is down to carb loading , which I believe is glycogen being replaced in your muscles or dehydration (your body clings onto water if its not getting enough) or whatever reason. This doesnt mean your weight loss is artifical as such. But, what it might mean, is that your "Normal" eating habits are way over your bodies requirements, hence how we are over weight in the firs place. Weight fluctuates too, so it isnt a science.
A bad day, a bad week can easily be overcome by 56 days doing well (about the number of days left). Dont look at what you havent achieved, but what you can achieve going forward. Rome wasnt built in a day, and it certaintly wont be knocked down in one.