We tend to think of all excess fat as the same (mostly unwanted). But in fact there are two types of fat that accumulate on your body when you take in too many calories. One kind is called subcutaneous fat. That's the stuff that accumulates on your hips and thighs, for example. The other type is called visceral fat and it's in your abdominal cavity where it can affect your internal organs.
Scientists have known for a while that visceral fat can be far more dangerous than subcutaneous fat but a new study in the Journal of the American Medical Association found that obese individuals with excess visceral fat could be at higher risk for Type 2 diabetes than those with excess subcutaneous fat.
The danger of excess visceral fat is one reason why some obesity researchers think that waist measurement is as important as Body Mass Index in determining obesity levels. If you're concerned about your own belly fat, here's a guide. According to the National Institutes of Health (NIH), the risk of Type 2 diabetes and heart disease goes up with a waist size greater than 35 inches for women or 40 inches for men.
The NIH has a good rundown of all known risk factors for these diseases.