I am a girl gymnast and weigh over 9 stone and am 5"3 . what is the best way to lose weight and gain a flat stomach ?

Gymnast: For flatter abdomen eat healthy ; get physically active. Calories burned > calories consumed. To tighten ab's: crunches, reverse crunches, exercise ball crunches, pelvic thrusts, lying leg raises, side bridge ; “bicycling” exercise on back. Engage in regular aerobic exercise (i.e. Running, swimming, nordic track, bicycling, kickboxing, walking, cross country skiing, hiking, etc.).