So, you’re thinking, “I’m in fair shape and have a lean body so I have nothing to worry about.” Right? Wrong! Researchers are now finding that it’s not how much fat you have, it’s where the fat is that really counts. And, it’s the fat in the inside that you can’t see that is the real killer, so where is this fat and what can you do about it?

The fat we are talking about is the internal fat or visceral fat surrounding vital organs such as the heart, liver and pancreas, all invisible to the naked eye and dangerous to your health. According to Dr. Jimmy Bell, a molecular imaging professor at Imperial College in London, “being thin doesn’t automatically mean you’re not fat.” Since 1994, Bell and his team have scanned nearly 800 people with MRI machines to create “fat maps” showing where people store fat. According to their data, people who maintain their weight through diet rather than exercise are likely to have major deposits of internal fat, even if they are otherwise slim.

Dr. Louis Teichholz, chief of cardiology at New Jersey’s Hackensack University Medical Center, backs this up by saying that just because someone is lean, it doesn’t make them immune to diabetes or other risk factors such as heart disease. This internal fat looks to be part of the problem. What is ironic about this new research is that overweight people who are active can be healthier than their lean, inactive counterparts according to Dr. Steven Blair, a University of South Carolina obesity expert. He goes on to say that “normal-weight persons who are sedentary and unfit are at much higher risk for mortality than obese persons who are active and fit.”

This is evident in the health of Sumo wrestlers. They probably have a better metabolic profile than some of their slim, sedentary spectators. Dr. Bell says this is because the wrestler’s fat is primarily stored under the skin, sub-dermal fat, not streaking throughout their vital organs and muscles.

So, there you have it. The news is not good, but don’t despair all you people out there who thought you were safe. Internal fat can be easily burned off by exercise, so even if you are slim and think you are okay, you better start thinking about getting off that couch and moving around some more. Your life may be dependent on it.