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The Fat You Can't See

When we look in the mirror, most of us can easily see some extra fat. But some of us are also carrying around fat that we can't see. So, we went into the operating room to see where that fat is hiding and why it's a huge health concern for the 60 percent of Utahns that are overweight or obese.

In the operating room at Utah Valley Regional Medical Center, Dr. John Mitchell and his team of specialists are about to perform a coronary by-pass surgery. The patient has a long history of coronary artery disease - having had his first of 10 angioplasties at the age of 38, and multiple stents as well. He is also considered obese - having a waist circumference of over 40 inches, making Dr. Mitchell's job more difficult.

”What we have here is we've opened the chest and we've opened the sternum and this is pre-pericardial fat that's overlying the sack around the heart. This is the type of fat that is worrisome”

Before he can perform the bypass procedure, Dr. Mitchell must first cut away the fat from around the heart and aorta.

“This layer right here is called the pericardium or the pericardial sack. We are going to be cutting through this layer... and that is the heart immediately under that layer. You can already see the fat on that heart. Oh look at that heart. That is so fatty!”

The kind of fat he sees on the patient’s heart is different from subcutaneous fat - or the stuff we see in the mirror, in that it collects near the organs and secretes proteins that can trigger health problems. A recent study found that over time, this can lead to increased heart problems, and decreased heart function. They also found that the amount of fat around a person's heart and aorta cannot be determined by their body mass index.

”And that's the danger. There are many patients that don't have much in the way of subcutaneous fat but have a significant burden of visceral fat, and we see that in the operating room.” Dr. John McCann, a cardio-thoracic surgeon, says imaging tools like an MRI can help doctors visualize the situation.

We looked at MRI images of the abdomen of an overweight woman. Moving from the back to the front, you can clearly see how the light-colored area - or fat - contrasts with the darkness of the organs, which are barely visible. You can also see the layer of subcutaneous fat - or the stuff we see in the mirror - all around the outside of her body. While MRI is considered the "gold standard" of tests, it is also very expensive. A less costly alternative is the ultrasound.

”Ultrasound is less expensive, it's less invasive, it's easy,” says Jon Woozley, a Physician’s Assistant who works with Mitchell and McCann. “So if we can develop those types of techniques to assess visceral obesity through ultrasound that will be very beneficial.”

And while doctors continue to search for ways to detect visceral fat, they do not yet know what causes a body to pack it around the organs. Their best guess is genetics.

“It's kind of lumped into that thing we call family history and of course those are things we really can't control,” Dr. McCann. “What you can control, however, is keeping your weight down and exercising.”

Doctor McCann also says that if you are having weight-related problems in your 30s and 40s, chances are good that they will come back to haunt you in your 50s, 60s, and 70s. But, you can start making changes today by eating healthfully and being physically active.

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