A large amount of visceral fat -- the fat that forms between your internal organs -- swells your abdomen and gives you a more prominent belly. Even if you have little excess subcutaneous fat, the kind you can pinch under your skin, you can still carry excess visceral fat. Reducing visceral fat isn't just a matter of appearance, either. That abdominal fat is associated with a higher risk of heart disease and diabetes.
Total Calorie Intake
Calories are units of measurement for energy. If you expend energy equivalent to the calories you consume, your overall body weight remains the same. Eat more calories than the energy you use during a day and you'll store that excess fuel in the form of fat. This formula applies equally to visceral and subcutaneous fat, so the means of reducing that fat is likewise the same: reduce calories and increase energy expenditure. Your body requires 3,500 calories to make a new pound of fat, so cutting this amount will subtract that pound from your abdomen. A 500-calorie reduction in your daily calories will shave a pound a week from your belly.
If you keep a daily journal of the foods you eat, you'll probably see where you're willing to skip some calories. Maybe you can leave the cream out of your coffee or switch to a piece of candy for dessert instead of a larger treat like a cupcake. You might find that soft drinks contribute too many calories to your daily diet. The important thing is that you make these decisions for yourself. A calorie reduction that allows you to choose which calories you want to keep and which you're willing to sacrifice will make your diet considerably easier to maintain than a rigid diet plan.
Researchers are still studying the efficacy of low-carb diets vs. low-fat and generalized low-calorie diets. While no clear evidence yet suggests that any particular type of diet affects visceral fat more than other types, recent research indicates that fiber may play a key role in fat loss. A 2011 study from researchers at Wake Forest Baptist Medical Center discovered that an "increased intake of soluble fiber was associated with a reduction in belly fat." More research will clarify these preliminary findings, but if you choose a low-carb diet, include sufficient fiber in your meals to reap the potential benefits of a high-fiber diet to fight visceral fat.
High-Fructose Corn Syrup
While Wake Forest's researchers have been studying the impact of fiber intake on visceral fat, Princeton University has conducted research into the effects of high-fructose corn syrup on weight gain and retention. The Princeton study focused on rats and found that the rats that were given high-fructose corn syrup exhibited "augmented fat deposition, especially visceral fat around the belly" compared to control rats and to rats that consumed an equivalent amount of sugar. A rat's physiology doesn't necessarily parallel that of humans, but you may choose to limit your consumption of this food additive. High-fructose corn syrup provides calories, but no nutrients, so you will not lack anything vital if you decrease your consumption of it.
While diet alone can help reduce your overall body fat percentage and therefore your visceral fat percentage, exercise also looks like a promising means to reduce visceral fat. No matter which diet you choose to lose abdominal fat, combining it with exercise may remove that fat more quickly and more completely than diet alone. Researchers at Duke University found in 2005 that "a modest exercise program equivalent to a brisk 30-minute walk six times a week can prevent accumulation of visceral fat," while more exercise began to reduce visceral fat.