Grab a measuring tape and wrap it around your body at the top of your hipbones; the number you see indicates how much abdominal fat you have.
For an average size female, you should be less than 35 inches; less than 40 inches for a male. Anything over those numbers means you're at increased risk for type 2 diabetes, high cholesterol, and heart disease—even if your body mass index (BMI) falls within a healthy range.
Do moderate-intensity cardio exercises like jogging, or biking for two or more hours every week, and add weight-bearing exercises to your regime. When you're getting in good shape and building lean muscle mass, your weight may not drop that much, but your waist size will.
So don't be too concern with the weighing scale, instead, pay attention to the way you look and feel overall. Okay? :)