According to my WW leader (I'm still not convinced if I want to believe her or not
) my body was in starvation mode. My weight loss has plateaued and when I talked with her about it she said it was because I was not eating the right amount of points a day (I had done creative point calculating in an effort to lose weight faster). Unfortunately, I can't go spend the newly found points on ice cream or chocolates, but I have been making a concerted effort to eat a little bit more - I
think it's working...at least the fluctuation has narrowed a lot.
I also know a while ago I was eating 1100 calories a day and working out 3-4 days a week and not losing any weight at all...so maybe there is some truth to the "starvation" mode theory.
You should try and see what works for you - If you feel fine at 1300 and are losing weight, than don't worry about it - if you notice that you aren't losing any weight (over a period of a few weeks) then it might be time to reevaluate the calories.