I had this problem this week - and i was on week one! My CDC (and other helpful souls on this forum) said it is most likely hormone fluctuations etc causing water retention, so she said if i stick with it she would expect a bigger loss next week as the water retention should resolve plus losing a few more pounds this week. I'm sure this must be right - it's impossible not to lose if you stuck to it - don't let it get you down - keep going, it will all be worth it when you weigh in next week!