Cardio and weight lifting. Using Metamucil will improve your digestion and help you feel slimmer and your ab muscles show better. My boyfriend is very happy after starting it to lower his cholesterol.
Are you overweight, in general, or just have the lower abdominal fat?
There are medical conditions that can cause abdominal fat, that should always be ruled out. Or it could just mean you to start working out in order to tone your muscles, which will also help eliminate the fat.