Subcutaneous fat, being closer to the surface, is always easy to see. Visceral fat, on the other hand, is not always visible from the outside. It jams up against the intestines, kidneys, pancreas and liver (and sometimes even inside the liver). We all have some visceral fat because it protects our internal organs, acting both as shock absorber in case of trauma, and as insulator to help us conserve body heat. While some visceral fat is necessary, too much can create serious health problems.
Most people think of fat as inert material, much like the rind of fat surrounding a steak. But fat is actually living, breathing, hormone-producing tissue. Fat is critical for survival because it stores food energy, and because it helps regulate body functions through the give-and-take of chemical communications with the central nervous system.
Subcutaneous fat may be visible and annoying, but it is relatively harmless. In fact, fat in the pear zone -- hips, thighs and buttocks -- helps to protect us from disease and is hard to lose. Scientists are still studying this fat to try and understand exactly why it is protective. Subcutaneous fat is a ready supply of energy or fuel only when we are pregnant, breast-feeding or starving.
Excess visceral fat, on the other hand, can be dangerous. Visceral fat is more metabolically active than subcutaneous fat, and most of what it does is harmful to the body.
Visceral fat decreases insulin sensitivity (making diabetes more likely), increases triglycerides, decreases levels of HDL cholesterol (the good one), creates more inflammation and raises blood pressure -- all of which increase the risk of heart disease. Instead of trapping fat, visceral fat releases more of its free fatty acids into the blood stream, further increasing the risk of both diabetes and heart disease.
The overall effect of excess visceral fat is that it creates a physical environment that is primed for heart disease and stroke, and greatly increases the risk for certain estrogen sensitive cancers such as post-menopausal breast and endometrial cancer. This is why apple-shaped women and men, who carry their weight around their waists, have an increased risk of metabolic and vascular diseases.
No matter which body shape you have, how old you are or how much you weigh, there are many things you can do to decrease your personal disease risk. Diet and exercise are only part of the equation; medical monitoring is critical, as is a change in mindset.
Women need to stop thinking of their weight problems and learn to accept themselves as women with figures. Doctors need to get in the habit of measuring waist size and body shape and not focus only on body weight. Men need to pay heed, as body shape and waist size is important for them too.
My top tips for getting started:
First step: Throw away or hide your scale and dig out a tape measure. From now on you should measure your health by inches instead of pounds.
Long-term goal: Lose just two inches of fat from your waist to significantly decrease your risks for the metabolic syndrome diabetes and heart disease.