You may have resolved to lose some of that belly fat because you think it looks unattractive.

The better reason is that such fat, known as visceral fat, is seriously unhealthy.

"The issue is health, not cosmetics," says Dr. Garth Davis, a bariatric surgeon at Houston Methodist. "The presence of visceral fat is a good predictor of the development of chronic metabolic disease, whether it's hypertension, heart disease or diabetes."

It's impossible to target belly fat when you start a program to slim down. But a reduction in weight will shrink your waistline and, most importantly, help reduce visceral fat, which lies underneath the abdominal wall in organs and in the lining around the intestines.

How do you know if you have visceral fat, why is it so dangerous and what can you do about it? Dr. Davis is here to answer those questions and more.

Not all fat is created equal

The fat that lurks just below your skin in much of your body — the kind you can pinch — is called subcutaneous fat. Such padding around the sides, glutes, thighs or upper arms may look cosmetically unpleasing, but it's actually fairly harmless.

Visceral fat, on the other hand, is very harmful. It accumulates deep within the abdominal cavity, where it can't be pinched, but pushes the belly out. It's called visceral fat because of the padding around the viscera (internal organs like your stomach and intestines).

""The heavier you are, the fuller the standard areas to store fat become, meaning that the fat ends up being deposited around your abdominal organs and your heart," says Dr. Davis. "In surgery with these patients, it's a very short distance from the skin to the belly, but then the belly is just filled with fat — fat in the liver, fat lining the intestines, fat everywhere."

The problem is, such fat is dangerous.

Dr. Davis notes that visceral fat cells are biologically active, essentially an endocrine organ that secretes hormones and other chemicals linked to diseases that afflict older adults. Among the chemicals are cytokines that boost the likelihood of heart disease and make the body less sensitive to insulin, which can bring on diabetes. They also produce a precursor to angiotensin, a protein that causes blood vessels to constrict and blood pressure to rise.

Are you an apple or a pear?

The most precise way to determine how much visceral fat you have is to get a CT scan or MRI. But there are easier ways to know whether you have a lot of visceral or subcutaneous fat.

The first is your body shape. People with a "pear shape," characterized by bigger hips and thighs, tend to have more subcutaneous fat; those with an "apple shape," characterized by a wider waistline, have visceral fat.

A tape measure is an even better way of keeping tabs. A waist circumference of more than 35 inches in women and more than 40 in men indicates an unhealthy amount of visceral fat.

Measure your belly at the level of the navel, not at the narrowest part of the torso. Don't suck in your gut or pull the tape tight enough to compress the area.

If your overall body size is large, those measurements might not be meaningful. Rather than focusing on an absolute cut-off, monitor whether your waist is growing over time. That should give you a good idea of whether you're gaining visceral fat.

The dangers of visceral fat

Cardiovascular health is the number one casualty of visceral fat. One large study of European women aged 45 to 79 found those with the biggest waistlines had more than double the risk of developing heart disease. It was nearly double even after adjusting for risk factors such as blood pressure, cholesterol, smoking and body mass index. Every additional two inches in the women's waist size raised their risk by 10%.

But visceral fat has been implicated in a number of other conditions as well:

• Asthma: In a large study of California teachers, women with high levels of visceral fat were 37% more likely to develop asthma than women with lower levels of visceral fat, a find investigators attribute to such fat's inflammatory effects throughout the body, including in the airways.
• Cancer: Visceral fat also has been linked to colorectal and breast cancer. A Korean study found that the chances of getting colorectal cancer nearly doubled among postmenopausal women who accumulate visceral fat. Similarly, a Dutch study found that participants with waistlines greater than 35 inches who lost 12 pounds had changes in biomarkers for breast cancer, like estrogen, leptin and inflammatory proteins, indicating a reduction in breast cancer risk.
• Dementia: A California study found people in their early 40s with the highest levels of visceral fat were three times more likely to develop dementia 30 to 40 years later than those who had the least abdominal fat at that age.

Other conditions linked to visceral fat include diabetes, stroke, compromised lung function, heartburn, sleep difficulties and migraine headaches.

The bottom line: Excessive visceral fat can nearly double one's risk of dying prematurely, according to a study of more than 350,000 European men and women published in The New England Journal of Medicine.

How you can combat belly fat

First things first: Everyone is somewhat genetically predisposed to store fat differently. Hormones play a role, too, notes Dr. Davis, which is why you see men carrying their weight around the middle and women carrying it around their hips and thighs.

Also, there are no weight-loss pills that target belly fat, and bariatric surgery is only for the morbidly obese: those with BMIs of at least 40.

But the good news, according to Davis, is that visceral fat is not that hard to lose. It just requires work.

Here's what you can do:

• Diet: There's no special diet to reduce belly fat. Dr. Davis advises his patients to eat "a predominantly plant-based diet, heavy on fruits, vegetables and legumes and light on sugar, meat, dairy and eggs, and ultra processed foods."
• Activity: Remember, it's not possible to spot reduce, so no amount of sit-ups is going to get rid of that belly fat. But when you shed pounds, belly fat usually goes first. Dr. Davis tells patients to be active but not to kill themselves — just 30 minutes to an hour of exercise five days a week, another 8,000 to 10,000 steps daily will make a difference. You don't need to run a marathon or become a bodybuilder, he says.
• Sleep: Getting the right amount of shut-eye helps. In one study, people who got 6 to 7 hours of sleep per night gained less visceral fat over 5 years compared to those who slept 5 or fewer hours per night or 8 or more hours per night.
• Stress: Do your best to limit it. Hang out with friends and family, relax in nature, meditate, exercise.

"We are hardwired to eat," says Dr. Davis. That's why, in the end, the mainstay for people to lose belly fat are lifestyle changes, eating a healthier diet, becoming more active. It can be done."