I have a question and hope you can help -- I am generally fit and in good health (by no means skinny). I jog/walk daily. I stick to a low carb (lean protein/vegetables) diet. I am 30 yrs old, 5'7 and usually flex between 135-139 pounds. I recently started an intense cardio kickboxing class which I LOVE. I go 3-4 times per week. Its an hour long class and it is super intense and works me out unbelievably. Ive been going for about 5 weeks now. My quesiton is -- why why why am I not only *not* losing weight.. but I've gained 3 pounds! I did not join this class to lose weight specifically -- I joined for the natural endorphins from exercise -- but I certainly dont want to gian weight.. My diet has not changed. The only difference is this class. Im discouraged and don't know if I should quit the class .. But I do enjoy it.. so Im stuck. Does you know why this could happen?? My mom keeps saying its because "your building muscle and mucle weighs more than fat" -- which I have heard a million times.. but its still really depressing..