The Two Types of Fat — Visceral and Subcutaneous
and Which Poses the Greatest Risk to You
It’s the dreaded “F-word” — FAT. Many of us are consumed with it … gaining it, fearing it and doing just about anything to get rid of it. Yet we all have it. Even lean adults have 40 billion fat cells; those who are obese may have 80 billion to 120 billion. But it’s not only the amount of fat that makes the difference between being healthy and unhealthy, it’s the type of fat, and where it’s distributed in your body.
People with large bellies are at a higher risk of dangerous visceral fat, but thin people, particularly those who lead sedentary lifestyles, are also at risk.
Visceral Fat Vs. Subcutaneous Fat
There are two types of fat: subcutaneous and visceral. Subcutaneous fat is the type found just underneath the skin, which may cause dimpling and cellulite. Visceral fat, on the other hand, is located in the abdomen and surrounding vital organs. It can infiltrate the liver and other organs, streak through your muscles and even strangle your heart; and you can have it even if you appear to be thin.
It is the latter, visceral, fat that is linked to everything from bad cholesterol and hypertension to diabetes, heart disease and stroke.
While you can spot visceral fat if you have a protruding “beer” belly, it’s not always that simple. Only a high-tech MRI (magnetic resonance imaging) can really show the body’s fat composition, and researchers are finding that thin people may also have high amounts of this internal fat. They’ve even developed a tongue-in-cheek name for them: Tofi (Thin on the Outside, Fat on the Inside).
‘”We’ve even scanned people who are underweight and found up to seven liters of fat inside them,” said Professor Jimmy Bell, head of the molecular imaging group at the Medical Research Council’s center at Imperial College in the UK.
Looks Can be Deceiving
While commonsense would dictate that Japanese sumo wrestlers, who eat upwards of 5,000 calories a day and are obese by most weight standards, are setting themselves up for a barrage of obesity-related health problems, studies have found that this is not the case. Why? MRIs of sumo wrestlers have shown they have hardly any internal fat.
“They have low cholesterol, they have low insulin resistance and a low level of triglycerides,” said Bell. “Their fat is all stored under the skin, on the outside.”
Meanwhile, someone who appears thin on the outside, yet doesn’t exercise nearly as much as a sumo wrestler, may be at risk of a host of health problems because their fat is being stored on the inside, and in the organs.
“This is particularly true of men who have a slim build but who do little or no exercise,” Bell said. “We know now that 40 percent of people have fat infiltration of the liver, which is linked to so many other health problems.”
Is Fat Really an Organ?
While once considered an inert storage system, researchers now know that fat cells are actually incredibly dynamic and intelligent.
“They were always thought to be poor, dumb sacks of lard,” said Roger Unger, an obesity researcher at the University of Texas Southwestern Medical Center. “It turns out that they end up being very talented, very versatile, very important players.”
Fat cells not only produce chemicals and hormones but they also send out signals that affect everything from our brain, liver, muscles and immune system to our mood and ability to reproduce.
“In the old days, people used to think fat tissue was a passive organ,” said Rexford S. Ahima, an endocrinologist at the University of Pennsylvania. “Now it’s obvious that it makes and secretes more hormones and proteins than probably any other. It’s at the center of a very complex system. It coordinates how much we eat, how much energy we burn, how the immune system works, how we reproduce. The list goes on.”
Jogging 17 miles a week for eight months can produce significant decreases in visceral fat, according to a Duke University study.
Do Genetics Play a Role in Visceral Fat?
Genetic factors do appear to play a role in fat storage and body shape.
“Our work so far has shown that you can take two men of the same age, with the same BMI