Even if you’re not overweight, it can significantly increase your risk for heart disease, cancer and dementia

Everyone knows that it’s unhealthy to be obese. What’s surprising to many people, however, is just how serious it can be to have “belly fat.”

Important recent finding: A study published in The New England Journal of Medicine that looked at more than 350,000 people found that a large waist can nearly double your risk of dying prematurely — even if your weight is “normal” (according to your body mass index, a measure of body fat based on height and weight).* Some people who don’t exercise but generally keep their overall body weight under control, for example, may have dangerous fat deposits around the abdomen.

Why is belly fat, in particular, so dangerous?

Here’s what you need to know…

WHAT’S YOUR SHAPE?

It’s been widely reported that about one-third of Americans are considered obese — the highest percentage of any country in the world. Though estimates vary, obesity, which is strongly linked to diabetes, heart disease, stroke and even cancer, is blamed for at least 26,000 deaths in the US each year.

Most of the body’s fat — known as subcutaneous (under the skin) fat — accumulates in the thighs, buttocks and hips. This fat distribution, which leads to a so-called “pear” body shape, applies to most women — and many men.

However, belly fat — generally associated with an “apple” body shape — presents the greatest risks. Also known as visceral fat, it is stored mostly inside the abdominal cavity, where it wraps around (and sometimes invades) the internal organs, including the heart. Long known to damage blood vessel linings, belly fat is a metabolically active tissue that secretes harmful inflammatory substances that can contribute to a variety of health problems. People with an apple body type are far more likely to die of heart attacks than those with a pear shape.

The worst of the worst: Hard belly fat (commonly known as a “beer belly”) is even more dangerous than soft belly fat — perhaps because many people with hard belly fat have high levels of C-reactive protein (CRP), an inflammation marker and risk factor for heart disease. Alcohol has been shown to slow fat metabolism by more than 30%, which is compounded by the fact that beer drinkers tend to eat high-calorie snack foods while drinking and beer itself is high in carbohydrate calories.

An increasing body of evidence is now linking belly fat to other serious health risks, such as…

  • Cancer. Both men and women with higher percentages of belly fat are more likely to develop a variety of cancers, including malignancies of the colon, kidney and breast.

  • Dementia. In a study of 6,583 adults, the bigger the belly, the greater the risk for dementia.

    • Surprising finding: Among those of normal weight who had excess belly fat, dementia risk was 1.89 times higher than for those of normal weight who did not have excess belly fat.

  • Lung problems. Lung function is reduced in patients with higher stores of belly fat, possibly because of the higher secretion of lung-damaging inflammatory chemicals.

  • Diabetes. An apple-shaped fat distribution greatly increases the risk for insulin resistance (a condition in which the body’s cells don’t use insulin properly) and diabetes.

    • The risks are even higher in those who are sedentary. People who have lost muscle mass, as a result, take in less blood sugar (glucose), which is used as fuel — further increasing diabetes risk.

  • Migraines. Researchers at Drexel University College of Medicine found that women with large amounts of belly fat were up to 30% more likely than lean women to suffer from migraine headaches.

    • INCHES THAT REALLY COUNT

    Research has shown that waist size — even in people who aren’t obviously overweight — is a key predictor of long-term health.

    Important finding: In a study reported in Circulation: Heart Failure, researchers found that a four-inch increase in waist size raised the risk for heart disease by about 15%, even in people of normal weight. Other studies report that each five-centimeter increase in waist size (a little less than two inches) raises the risk for premature death by 13% in women and 17% in men.

    My recommendation: A waist size of 35 inches or less in women and 40 inches or less in men. Even slight increases above these numbers significantly raise your health risks.

    Best way to measure your waist: Place a tape measure just below your navel, exhale gently, then record the measurement.

    STRATEGIES FOR WAIST LOSS

    There are no proven ways to selectively reduce accumulations of visceral fat. My advice…

  • Strive for healthy overall weight loss. People who follow a sensible diet, such as the American Heart Association’s No-Fat Diet (www.americanheart.org) or the Weight Watchers plan (www.weightwatchers.com), lose weight proportionally — that is, they lose more weight from areas where they have the most body fat. Someone with a high percentage of visceral fat will show the effects most in the abdomen.

    • Another advantage of such diets is that they include large amounts of natural, wholesome foods, such as vegetables and whole grains. A plant-based diet supplies large quantities of anti-inflammatory, disease-fighting compounds.

    Important: When you’re trying to lose weight, avoid or eliminate most dietary sugars — not only from sweet snacks, but also from processed carbohydrates, such as white bread, snacks, beer and fruit juices. These foods have a high glycemic index — that is, they cause a rapid spike in blood sugar that may increase the accumulation of visceral fat.

  • Drink green tea. A study in the Journal of Nutrition found that obese adults who drank green tea lost about twice as much weight over 12 weeks as a control group even though people in both groups followed similar diets and exercise patterns. It’s thought that compounds known as catechins in green tea increase metabolism and accelerate the breakdown of fat.

  • Focus on aerobic exercise. This is the best way to increase metabolism, burn calories and reduce fat. Aerobic exercise is more effective than resistance workouts (such as lifting weights) because it burns more calories per hour.

    • There’s some evidence that overweight women who engage in sustained aerobic workouts — such as 20 minutes or more of brisk walking daily — can lose up to one inch of belly fat in just four weeks.

  • Turn down the thermostat. Researchers have recently made exciting discoveries related to so-called “brown” fat, which has been shown to burn energy to generate body heat.

    • This type of fat was once thought to disappear after infancy, but new studies indicate that it’s present in many adults and can be activated by exposure to cool temperatures — roughly 61°F.

    People who are overweight or obese may have lower brown fat activity, which could be an underlying cause of weight gain. Spending a few hours in cool temperatures — say, at night when you sleep — could potentially increase the body’s energy expenditure, which, over time, could result in weight loss. More research is needed, but in the meantime, set your thermostat as low as is comfortable year-round.

    *To calculate your body mass index, go to the National Heart, Lung and Blood Institute Web site, www.nhlbi.nih.gov/health/.