Temporary gains are often common... especially at the beginning, which I know put me off exercise for ages! Sometimes the cause can be dehydration... as muscles have a tendency to hang onto water, so make sure you're drinking plenty. Maybe also check that you haven't got too high a calorie deficit between calories eaten and calories burned... you may find it useful to fill in your diet/exercise calendar to check this. I actually found that after introducing exercise I had to increase my points. So you may want to calculate your Activity Points for the exercise... then perhaps eat a few into those on top of your daily points. You may have to experiment a little to find a happy medium... but good luck! Above all though don't give up... as that exercise will definitely shrink you loads of inches in the long run. ;o)