Spot fat loss does. Not occur naturally. By losing weight in general some will probably be abdominal fat. But, we don't get to choose what area of body fat is lost from. Eat healthy ; be physically active. Calories burned must > those consumed. Tighten ab's: crunches, reverse crunches, exercise ball crunches, pelvic thrusts, lying leg raises, side bridge ; “bicycling” exercise on back. Do regular aerobic exercise.
Some exercises help. To help the tummy look flatter, one can do exercises to build very strong abdominal muscles. It will take a lot of work, and will burn off calories. One must not eat more calories than he burns off, or he cannot lose weight. Helpful weight loss foods are natural foods that take time to chew but contain few calories. Examples include carrots, celery, and iceberg lettuce (without salad dressing).