Am I losing too much water weight too fast? -

i am 5 6 , 200 lbs. I recently started taking a vitamin/mineral supplement to aide my weight loss program. I lost 8 lbs. in 14 days while on a low-carb diet and hitting the gym every other day. Here is the link to the nutrition facts on what vitamin.mineral I am taking. http://www.nutritionexpress.com/lindberg/see+all/lindberg+varsity+2+powder+multi-vitamins+minerals+orange+cream+3+pounds.aspxI noticed the high B-vitamin content and wonder if its coming from those? Is this just a short term side effect? Should I lessen the dosage? Any recommendations? Thanks.

You must drink lot of water, it s very important.