now that i've gotten that out of the way... yes, cardio can be catabolic which means it's burning muscle as well as fat... too much cardio can result in a decreace in lean mass, which can decrease the metabolism and slow fat loss...
it's my opinion that the only real time excessive cardio should be done is when you have muscle to spare....
For your cardiovascular system.... It can't hurt. 3 times a week, 20 minutes per session. If you lead a basically active lifestyle, you're already way ahead of the curve.
But you don't need cardio to stay lean, or to get lean.
Welllllll it all depends on your goals of course. I believe both Belial and Wilson6 are guys, which doesn't discredit their opinions and experience, but is something to keep in mind. Without a doubt, too much cardio is catabolic. But from a lifestyle point of view (let's just say I've been on too many hikes/kayaking/climbing trips with machos BB guys that were NOT fit in the cardiovascular sense of the word) cardio IN MODERATATION is good for your overall health and lifestyle. As a bodybuilding female you have to weigh up the pros and cons. Cardio is counter productive to short term, single-minded maximal mass gains. It is beneficial to long term health. Don't let anyone try to convince you that weight/interval training is as good or better for your long term health as moderate cardio. But it is certainly the best thing for short term gains.
Endurance cardio will definitely make you retain fluid and fat. This is nature's way. In the days before water stations and glucose drinks we no doubt were better adapted if we could hold on to precious water and fat reserves. These days, where everyone wants to look lean and mean, too much cardio can make you look smooth and flat.
so what exactly do u consider too much cardio???? i would do about 40 min of cardio in the am,,,,,,,,go back in the pm and do weights, and then about 20 min more of cardio. is that too much?