Lol, if you are like me, i try everything i can to lose the last few ounces before i get weighed....earrings out, watch and belt off and have a wee just before getting on the scales lol! ;-)
I have to admit I have had the same problem with not going to the loo but there are things like fibresure that you can take - speak to your CDC and they can advise you.
Oh im in week one at the moment (only one day 2 thought!) im soo excited for weigh in day as well now! let me know how you get on I love hearing how everyone is doing!