Although you may appear thinner when you wear a girdle, the girdle doesn't strengthen or tone your abdominal muscles. Girdles just temporarily compress and redistribute fat and skin around the abdomen. When it comes to a flat stomach, diet and exercise — not undergarments — are what count. Although you can't "spot reduce" abdominal fat for a flat stomach, you can lose weight overall with dietary changes and aerobic exercise. Core exercises — which target the muscles in the abdomen, back and pelvis — can help too. Examples of core exercises are the abdominal crunch and the bridge. But any exercise that uses the trunk of your body without support counts, including Pilates and fitness ball exercises. Next questionWeightlifting belt: Do I need one?