I always say that it doesn't matter how much your lose in the first week but how much you've lost by the last week! By then you won't give two figs about the first week. It is mostly water so how much you lose can depend on the water you were retaining to start with. There are a few people who have posted here that started at around the same weight as me but lost a lot more in week 1 ( I was 3lb). It doesn't mean they were doing the plan better than I was just that they lost more water. So it's best not to get too hung up on the numbers.