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.
It's that deeper fat -- called "visceral" fat -- that may be the bigger problem, even for thin people.
Deep Belly Fat
You need some visceral fat. It provides cushioning around your organs.
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?
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."
Thin People Have It, Too
Even if you're thin, you can still have too much visceral fat.
How much you have is partly about your genes, and partly about your lifestyle, especially how active you are.
The key is to be active, no matter what size you are.