What's the quickest way for a 28-year-old woman to lose body fat if she's 55 pounds overweight?

Even if you have a rock-hard pack of abs, you still have belly fat. And how much flab you have around your middle has a big impact on your health. Here’s help getting a handle on your belly fat.

People store most of their fat in two ways – one you can see and one you can't. The fat you can see is just under the skin in the thighs, hips, buttocks, and abdomen. That's called subcutaneous (under the skin) fat.

The fat you can't see is deeper inside, around the vital organs (heart, lungs, digestive tract, liver, and so on) in the chest, abdomen, and pelvis. That's called "visceral" fat. Many people are self-conscious about the fat they can see.

But actually, it's the hidden fat -- the visceral fat -- that may be a bigger problem, even for thin people. We all have visceral fat -- and it isn't all bad. It provides necessary cushioning around organs.

But, the fat doesn't just sit there. It makes "lots of nasty substances," says Kristen Hairston, MD, assistant professor of endocrinology and metabolism at Wake Forest School of Medicine. And having too much of it is linked to a greater chance of developing high blood pressure, type 2 diabetes, heart disease, dementia, and certain cancers, including breast cancer and colon cancer.

When a body's obese, it can run out of safe places to store fat and begin storing it in and around the organs, such as around the heart and the liver. What kind of problem does that create? Carol Shively, PhD, professor of pathology-comparative medicine at Wake Forest School of Medicine, says, “Fatty liver disease was, until recently, very rare in non-alcoholics.

But with obesity increasing, you have people whose fat depots are so full that the fat is deposited into the organs. In addition, she says, more fat is also being deposited around the heart. The most precise way to determine how much visceral fat you have is to get a CT scan or MRI.

But you don't need to go that far to get a sense of whether or not the fat inside you is putting your health at risk. Get a measuring tape, wrap it around your waist, and check your girth. Do it while you're standing up, and make sure the tape measure is level.

For the minimal effect on your health, you want your waist size to be less than 35 inches if you're a woman and less than 40 inches if you're a man. Having a "pear shape" -- fatter hips and thighs -- is considered safer than an "apple shape," which describes a wider waistline. “What we’re really pointing to with the apple versus pear,” Hairston says, "is that, if you have more abdominal fat, it’s probably an indicator that you have more visceral fat.".