How to reduce belly fat.

Surprise: Everyone has some belly fat, even people who have flat abs.

That's normal. But too much belly fat can affect your health in a way that other fat doesn't.

Some of your fat is right under your skin. Other fat is deeper inside, around your heart, lungs, liver, and other organs.

It's that deeper fat -- called "visceral" fat -- that may be the bigger problem, even for thin people.

measuring waist

Deep Belly Fat

You need some visceral fat. It provides cushioning around your organs.

But if you have too much of it, you may be more likely to get high blood pressure, type 2 diabetes, heart disease, dementia, and certain cancers, including breast cancer and colon cancer.

The fat doesn't just sit there. It's an active part of your body, making "lots of nasty substances," says Kristen Hairston, MD, assistant professor of endocrinology and metabolism at Wake Forest School of Medicine.

If you gain too much weight, your body starts to store your fat in unusual places.

With increasing obesity, you have people whose regular areas to store fat are so full that the fat is deposited into the organs and around the heart, says Carol Shively, PhD, professor of pathology-comparative medicine at Wake Forest School of Medicine.

How Much Belly Fat Do You Have?

The most precise way to determine how much visceral fat you have is to get a CT scan or MRI. But there's a much simpler, low-cost way to check.

Get a measuring tape, wrap it around your waist at your belly button, and check your girth. Do it while you're standing up, and make sure the tape measure is level.

For your health's sake, 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" -- bigger 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."