What's the best way to lose excess tummy fat, which exercise: i am doing sit ups and stomach crunches?

Abdominal exercise: While sit-ups can increase abdominal muscle mass they will only minimially help you loose stomach fat, if any. To loose adipose tissue work on a cardio mix (walking, running, biking, swimming, circuit training, etc - mix it up). Keep in mind that you can not target one specific area of the body to loose weight, and over time the adipose will decrease in many areas of your body (stomach included).

Spot fat loss does : Not occur naturally. By losing weight in general a certain amt will be abdominal fat. Eat healthfully ; be physically active. Calories burned must > calories consumed. To tighten ab's do crunches, reverse crunches, exercise ball crunches, pelvic thrusts, lying leg raises, side bridge ; “bicycling” exercise on your back. Get regular aerobic exercise.