What can we do to keep it from reaching unsafe levels? "One of the most effective treatments for targeting visceral fat is exercise, maybe more so than diet," says Kerry Stewart, a professor of medicine and director of clinical research exercise physiology at the Johns Hopkins School of Medicine. "You will see a reduction in waist size, which includes both a loss in subcutaneous and visceral fat, but the visceral fat will go down even more so than the subcutaneous fat." Cardiovascular activities like running, biking, or rowing count more towards visceral fat loss, says Stewart, since they burn more calories than other types of exercise. Still, most doctors will say, something is better than nothing.
Don't discount your diet though, which can help you lose visceral fat and body weight in general. Melina Jampolis, a physician nutrition specialist with practices in San Francisco and Los Angeles, stresses the importance of cutting back on sugar, "especially sugary beverages and refined white carbohydrates," since they're high in calories and nutritionally empty. Replace them with lean protein like skinless poultry and fish or healthy fats like olives, nuts, seeds, and avocados. Eat more fiber; this includes oats, beans, and barley. High-fiber foods can help you feel full longer so you're less likely to overeat. The Institute of Medicine's daily recommendation of fiber for adults under 50 is 38 grams for men and 25 grams for women. It's suggested that men and women 51 years and older eat 30 grams and 21 grams a day, respectively. To achieve this, increase your consumption of fruits, vegetables, and whole grains—"three servings of whole grains per day have been linked with lower levels of visceral fat," says Jampolis.
Last, but not least, consider your sleep habits. A 2010 study from the Wake Forest University School of Medicine showed that too little sleep—five hours or less—or too much sleep—eight hours or more—was related to increases in visceral fat. And while diet and stress may also have played a part, researchers say sleep itself appeared to be a risk factor.
When all is said and done, shedding fat for those who are overweight, whether it's subcutaneous or visceral, is a win-win situation. The Centers for Disease Control and Prevention defines overweight adults as having a body mass index, or BMI, between 25 and 29.9, while those who have a BMI of 30 or higher are considered obese. It should be noted that BMI correlates with body fat but does not measure it directly. To determine your BMI, simply take your weight in pounds, divide by your height in inches squared, and then multiply by 703. For example, if your weight is 200 pounds and your height is 6 feet, the calculation would be: [200 / (72)²] x 703 = 27.
Losing weight—through diet, exercise, and other behavioral changes like meditation to relieve stress—can help stave off a host of problems including heart disease, stroke, cancer, gallbladder disease, type 2 diabetes, osteoarthritis, sleep apnea, infertility, and depression. Now that's something we can all live with.
Corrected on 4/30/2012: An earlier version of this article incorrectly spelled the name of Ernst Lengyel, a professor of obestetrics and gynecology at the University of Chicago.