that time of the month/weight loss

ok, i KNOW that i am not only doing the mc for weight loss, so no lectures please! lol ;) but i do have a question, i started on tues the 3rd and am now on day 4. on wed (day 2) i had lost 2lbs and being honest, it was nice to see. i started working out on wed, thur and today fri and have noticed that i have only lost a 1/2 lb since my initial first two....but i am just curious as to weather or not this has happened to any of you ladies who have done the mc during the beginning and/or during 'that time of the month'? also, i am wondering if this is just water retention that goes w/that time and will hopefully go away....any help out there?