Losing weight can leave loose skin on your abs as well as on the rest of your body. You can tell this is not fat if dieting and cardio exercise do not reduce it and if more dieting increases the looseness. A stomach that slims with cardio or a lower-calorie diet has either visceral fat (easiest to burn and more unhealthy) or subcutaneous fat (harder to burn but less unhealthy.)
Saggy, Baggy Stomach Skin
Pregnancy, losing a large amount of weight and yoyo dieting all can leave loose skin on your abs. This skin can be difficult to get rid of, and its appearance can be frustrating after you worked hard to lose weight. Loose skin on your stomach can be firmed and tightened with exercise that targets all four abdominal muscle groups. For extremely stretched out skin, your best bet might be to aim for building a muscular "six-pack" look with exercises that use weights. If you plan to lose weight and want to prevent loose skin, aim to lose no more than two pounds each week and include exercise to firm your stomach while you slim down.
Harmful Visceral Fat
You can't pinch visceral fat. It is deep, firm fat that shows up as a bulging belly you may have even if you are otherwise in shape. This is excess fat that is stored in the stomach when your caloric intake exceeds the calories that you burn. Visceral fat is unhealthy because it releases harmful inflammatory compounds that increase your risk of cancer, diabetes and heart disease, according to Metabolic Effect. These compounds also increase the amount of cortisol in the fat itself, which stimulates growth of more fat. Fortunately, visceral is the type of fat that is most quickly burned with cardio exercise, and it can also be reduced with a lower-fat, lower-calorie diet.
Subcutaneous Belly Fat
Subcutaneous fat is stored on the lower belly, and you can pinch it, but it's not loose skin. Women often store this fat, sometimes called "saddlebags," on the hips, butt and thighs. Men often store this type of fat, sometimes called "love handles," on the sides of the stomach above the hips. There is a decreased blood flow to this fat, and it stubbornly resists being burned away by exercise. A healthy diet of low- and non-fat protein, fiber-rich simple and complex carbohydrates (including fruits and vegetables), and two daily servings of healthy fats like olive oil and peanut butter is the way to reduce subcutaneous fat.
Tight, Firm Abs
Try targeted stomach exercise to tighten loose skin before you resort to the extreme measure of surgery. Firm stomach muscles can hold your stomach in like a corset and improve the appearance of loose skin. The double crunch, which adds bent leg lifts to the basic crunch, firms your upper, middle and lower stomach. To build visible abdominal muscle, lift a weight above your head as you lift your upper body and keep your legs straight. Standing twists holding a bar strengthen the deep stomach muscles, and the sides and lower waist -- internal and external obliques. Use a weighted bar to build muscle. For all abdominal exercises, start with three sets of 15 and build up to 25.