There is so much more than just cardio that goes into fat loss. Where were your calories prior to the 2000 calories per day? How often do you weight train? When are you doing the cardio? How many meals per day, what types of foods? Also how much water are you drinking? These are other things to be considered. Problem with cardio is your body adapts just like anything else. I always suggest starting with less then going up from there. For example I do 30mins first thing am every day right now. When my weight loss stops I can adjust not only the calories but also the amount of cardio. Type of cardio is important as well, not just strolling on the treadmill if you know what I mean, some people will do that day in and day out and wonder why they are not getting the results they want. Cardio should be kicking your ass as well as the weight training. This of course is only my experience.