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Episode 27 : Visceral Fat: An Invisible Killer

Release Date: October 17, 2008

Dr. Meyerson: Hi, I'm Dr. David Meyerson, Cardiologist at Johns Hopkins and your host for this edition of Vascular Disease Foundation's Health Cast.

We're very excited to be able to bring you excellent, easy to understand science on all topics relating to heart and blood vessel diseases as a public service.

As a public education forum, the Vascular Disease Foundation is made up of representatives of the premier medical and scientific advisory groups in the country that relate to vascular diseases. These are groups that use peer reviewed science to verify that the information that you are getting is nationally recognized as the very best and most reliable data available.

Clearly there has been an explosion in the numbers of people in the United States and around the world who are overweight or obese; two conditions directly related to the epidemic of type II diabetes. Though diabetes affects people of all ages, it strikes especially hard on those that are middle age or older. Besides increasing the risk of heart attack, obesity and diabetes greatly amplify the risk of eye and kidney diseases, foot problems, peripheral arterial disease -- each a source of much disability.

But what is important to know is that not all fat is the same and different fat conveys different risks.

Joining me in studio is Dr. Kerry Stewart. He is Professor of Medicine, Director of Clinical and Research Exercise Physiology at the Johns Hopkins University School of Medicine and a former member of the Board of Director of the Vascular Disease Foundation.

Dr. Stewart, thanks for being with us.

Dr. Stewart: Thanks for having me.

Dr. Meyerson: And so there's some exciting things to talk about. All fat is not the same, I understand.

Dr. Stewart: Well, there are differences in fat and what we have been studying more specifically is where the fat is actually located, because where it is deposited in the body confers different levels of risk.

Dr. Meyerson: Well not, not for -- let's get back to the diabetes for a moment. Not everyone who has diabetes is markedly overweight. Can you be near your normal size and have an excess of this so-called harmful visceral fat?

Dr. Stewart: Yes. The visceral fat is the fat that is internal. It's within the abdominal cavity. It's under the skin. It's under the muscles of the belly and you can't see it. You can't see it, we can see it in our laboratories when we do special imaging such as a magnetic resonance image or a CT scan, but --

Dr. Meyerson: So it's much harder to measure than just pinching an inch?

Dr. Stewart: Absolutely. It's deep within the abdomen. It's also called deep fat.

Dr. Meyerson: And so what, what's the best way to measure deep fat?

Dr. Stewart: Well again, the best way we measure it in our laboratory when we do research is through these special imaging tests. Although if you have a lot of fat around your waist, in other words if you have a large waist, you're also likely to have a great deal of this internal visceral fat. They don't -- it's not a perfect correlation. You know, it's not -- not everyone who has the big gut necessarily has a lot of visceral fat, but many people will.

Dr. Meyerson: Is the so-called guy with the beer belly, is that visceral fat?

Dr. Stewart: Well what you see is this fat that's under the skin. The visceral fat is much deeper than that, so you really can't see it.

Dr. Meyerson: So in other words, you would have to go underneath the skin, underneath the normal fat that we all have under our skin, underneath the muscles of the abdominal wall, all the way inside the abdominal cavity where the liver and the kidneys and the intestines and everything else are in order to see that fat. Is that correct?

Dr. Stewart: That's right. This is the fat that is deep. It wraps itself around the organs, so it's not the fat that you see. We call it the invisible killer.

Dr. Meyerson: So it's my understanding that many people with high visceral fat levels also tend to have many other very important risk factors for heart disease and diabetes, and these would include being intolerant to higher levels of glucose, having a low level of HDL or good cholesterol and they also have high blood pressure and high triglycerides which is another harmful fat that we see in the circulation and this would be so-called -- the so-called metabolic syndrome and people that have this get heart and blood vessel disease very, very early, don't they?

Dr. Stewart: That's very true. It's much more common to see heart disease and diabetes in an individual who has more than one risk factor. The more risk factors you have, the more likely you are to develop either heart disease or diabetes and visceral fat is a contributor to metabolic syndrome.

Dr. Meyerson: I, I would like to use an analogy for just a minute Kerry. Some of our viewers, either in -- they may be old enough to have seen it when it was first broadcast and some maybe were fortunate enough to see it during replays, reruns on Nick at Night or other programs, but do you remember in the Three Stooges when Mo would stand on Curly's shoulders in front of an elevator and the elevator was the old kind of an elevator that had an arrow pointing from one to two to three to four to five to six and so Curly – Mo would stand on Curly's shoulders. Mo would grab the arrow on, on the sixth floor.

Dr. Stewart: Okay.

Dr. Meyerson: He would take the arrow and bring it back to one and the doors would open. Now we all know that that doesn't happen in real life, but my question, my analogy -- now that I got your attention hopefully --

Dr. Stewart: I'm still confused, but I'm, I'm going along with you.

Dr. Meyerson: Good, good, good. Is visceral fat, like the elevator in the Three Stooges? Example, does its presence cause harm? Does the fact that the fat's there, does that cause harm to the blood vessels or is it an, an indicator that a very harmful environment for accelerated vascular disease exists? Now this may be an important research question.

Dr. Stewart: Well I -- the visceral fat is part of the environment that leads to an increase of heart disease and diabetes, so I -- if I understood your analogy, I think the answer then is yes.

Dr. Meyerson: So if we reduce the visceral fat, the --

Dr. Stewart: And if I didn't understand your analogy, then the answer is no.

Dr. Meyerson: Then the answer is still yes. Okay. So then it can -- so that brings us to the question, you know there are thousands of diets and different types of exercise programs, do we actually know what is the best way to remove harmful visceral fat? Is a dietary approach the most important? Is an exercise approach the most important? Is some sort of combination most important? Can you give us any insight?

Dr. Stewart: Well most of the research that's been done up until now has actually shown that exercise is the most -- is, is, is probably the most effective way to reduce visceral fat. You do get some loss of visceral fat with diet, but you seem to get an accelerated loss of visceral fat with exercise so if you put together what we do know, I, I -- the best advice is to lose weight through a combination of diet and exercise, but don't forget the exercise part.

Dr. Meyerson: That's the most critical because if you just starve yourself, then what happens? The body thinks it's on a desert island. It says we're not going to burn calories because we're afraid that the, the next food shipment isn't going to come and then you end up burning what? Muscle and other things.

Dr. Stewart: Well you end up -- that's exactly right. You end up losing muscle tissue as well as fat tissue and that's actually no good.

Dr. Meyerson: No good. Okay. So --

Dr. Stewart: Well the muscle is the body's -- if you think of the muscle or what we call lean tissue, that's the metabolic engine of the body. That's what's burning the calories and if you start losing muscle at a rapid rate, your ability then to burn calories is reduced so it becomes more difficult to lose weight as you lose weight.

Dr. Meyerson: And you don't care, for example, whether that activity -- the physical activity that people do -  is walking or swimming or it doesn't have to be a jog or it doesn't have to be a weight lifter. It can be anything that moves large muscle groups. Right?

Dr. Stewart: Yes. In fact there have been new guidelines that were just published about a couple of weeks ago talking about what is now the best approach to exercise and that, it continues to be a combination of what we call aerobic exercise where you're using the large muscles thirty, forty-five minutes at a time, walking, swimming, cycling; that in combination with some weight lifting is still the recommendation in terms of an effective exercise program.

Now it's also realized that not everyone can get to a gym and so that the exercise that you do doesn't necessarily have to be all at once. So taking ten minute walks here and there during the day, as long as it adds up to a minimum number of minutes, at least thirty minutes a day, will still product health benefits.

Dr. Meyerson: I want to make sure that our listeners who are fifty and sixty and seventy and even in their eighties and nineties who want to remain active, because you, you can't be an active octogenarian or you can't be active when you're ninety unless you try to remain active when you're fifty and sixty and seventy, but it's never too late to start, but for our listeners that have low back problems and have limited ability, but do want to get around, walking is still wonderful, isn't it?

Dr. Stewart: Absolutely. And getting back to your point about, you know, when you're older. I, you know, we never give out cliches, but –

Dr. Meyerson: I feel one coming on.

Dr. Stewart: -- but let's make an exception here and I think one that is most applicable here is use it or lose it.

Dr. Meyerson: Okay.

Dr. Stewart: And once you lose it, it's harder to retrieve it.

Dr. Meyerson: So if you want to be successful, get off your tush.

Dr. Stewart: Absolutely.

Dr. Meyerson: So, and let me go back and say one thing about how muscles burn calories. It is my understanding that when large muscles have been active like you've been using them for walking and, and more activity than, than just being a couch potato, they continue to burn calories even when you're sitting and doing nothing. Isn't that correct?

Dr. Stewart: Yes. The more muscle you have, the higher your, what we call metabolic rate, resting metabolic rate, so the engine is kind of always going a little bit and burning calories.

Let, let, let me clarify to people though what calories, what a calorie is. A calorie is energy so when you do exercise or just anything to just live, you need energy for the muscles and the organs to work properly.

Dr. Meyerson: It's like gas in the gas tank.

Dr. Stewart: It's exactly like gas in the gas tank and if you don't burn those calories, they get stored in the, they get stored like gas in the gas tank, but in this case, if you don't use enough, they get stored as fat and over time you start building up these big deposits of fat; not only the fat you see which is the fat that's under the skin, but also this internal fat --

Dr. Meyerson: This visceral, this harmful visceral fat that we started talking about.

Dr. Stewart: -- this very, this visceral fat which is very, very metabolically active. With that, I mean is that fat is not just a passive substance. It's actually considered a living organ in itself and one of the harmful things that fat actually --

Dr. Meyerson: I could see a horror movie being written right now.

Dr. Stewart: Well, remember The Blob?

Dr. Meyerson: Exactly.

Dr. Stewart: Well it is not quite like The Blob, but it does produce a whole bunch of chemicals and --

Dr. Meyerson: And that's what we talked about. It lowers the good cholesterol, it makes the body less able to handle sugar and makes you more likely be diabetic. It pushes the triglycerides up through the roof and all of that together, makes every blood vessel in the body function more poorly and more likely to block down.

Dr. Stewart: That's right and the -- but, but the chemical that I was going to refer to specifically are these inflammatory substances or what we call Cytokines and these are the substances that cause inflammation throughout the body. It causes kind of an irritation of the blood vessels that make them much more susceptible for these cholesterol deposits and then plaque builds up and blockages occur. If it occurs in the legs, it's peripheral arterial disease. If it occurs in the heart, it's a heart attack. If it occurs in the blood vessels leading to the brain, it's a stroke.

Dr. Meyerson: So again, we've talked a bit about how important exercise really and truly is and just to review, the exercise -- increased exercise will lower your blood pressure, it will lower your cholesterol, the bad cholesterol and raise your good cholesterol. It makes the blood cells, called platelets, the ones that protect us from bleeding, but the ones that also clot off inappropriately in arteries that nourish the heart muscle and cause heart attack or in the brain causing stroke. It makes those platelets less likely to be sticky when they shouldn't be because platelets that stick together on an ulcer that's in your stomach preventing it from bleeding are your best friend.

Platelets that stick together in an artery that nourishes the heart muscle or an artery that nourishes the brain are anything but your best friend, so exercise makes these platelets less likely – it also increases the health of the inner lining of the blood vessel wall making it less likely to break down. And also it helps, Kerry you have done research on this, it helps form collateral circulation for people who have peripheral vascular disease. The exercise actually makes them exercise more and do better with less blood flow. Isn't that right?

Dr. Stewart: Well, we think that's part of what happens when someone exercises if they have peripheral arterial disease that there are small new blood vessels that form, although the evidence for that in humans is actually not as strong as what we've seen in some animal studies; mainly because it's very hard to measure these very tiny little blood vessels in a human, a living human. But what we do know very specifically and for sure is that exercise helps to improve the ability of the muscles to get the most amount of oxygen out of whatever blood supply is getting to that muscle so that the muscles become much more efficient. It's like a car now that can run at fifty miles a gallon as opposed to ten miles per gallon.

Dr. Meyerson: Let me ask you this. When -- if, if, if our listeners are home or in their offices or in their cars and they're saying to themselves, well this makes a lot of sense. How do I know if I have excess visceral fat? Is it one of those things like when the Supreme Court talked about -- you know what I'm talking about, right?

Dr. Stewart: No.

Dr. Meyerson: No? Okay. When the Supreme Court -- I was trying to see if you would remember When the Supreme Court talked about pornography.

Dr. Stewart: Oh yeah --

Dr. Meyerson: One of the Supreme Court Justices says, "I can't define it, but I sure as hell know when I see it." Now I don't think that's the same here. What does -- our -- what do our listeners do? They can't just all get CT scans and PET scans and fancy scans --

Dr. Stewart: No, no, no and I --

Dr. Meyerson: -- to tell if they have increased visceral fat. Is there an indirect measurement so they could get a better idea?

Dr. Stewart: Absolutely. And again, I mentioned this I think earlier and the best indirect measurement is your waistline so that if your waist size is big, you're much more likely to have visceral fat than if your waistline is small. Now there are some exceptions to that. It's not a perfect, but that's why we call it an indirect measure.

Dr. Meyerson: Is this the so-called body habitus that you're better off looking like a pear than looking like an apple?

Dr. Stewart: That's right and when someone has that configuration, so to speak, they have what's called abdominal obesity, so that if your waist size is bigger than your hip size or your waist to hip ratio is greater than one; your waist is bigger than your hips, you have a condition called abdominal obesity.

Now there are actually more specific measures of waist circumference at which someone is at increased risk. So for a woman, if their waist size is thirty-five or higher, or for a man if their waist size is forty inches or higher, that indicates that they have abdominal obesity and that also indicates that they have a much higher risk of having this visceral fat as well.

Dr. Meyerson: Are you sure? I didn't -- this almost sounds unfair. I can -- a man when his waist goes beyond forty, I can see him in my mind's eye getting very round, but is it fair to a woman who's waist is more than thirty-five? That doesn't sound like that big a waist.

Dr. Stewart: Well, don't forget -- and I'm sure you've seen pictures of this, women do have different body shapes than men. Women tend to have a more narrow waist and larger hips; that's part of what they need for childbearing purposes, so we've evolved that way, but when a waist size in a woman starts to get above thirty-five, that is too big.

Dr. Meyerson: I'm just sticking up for our female listeners. It doesn't sound like that, that big a lady, so, so I guess what you're saying is that all weight loss is not the same.

Dr. Stewart: No it's not. And again, if you go on a starvation diet, not only will you lose some fat, you'll also lose muscle so that's no good, but if you go on a even keeled slowly reduced, slow reducing diet -- by slow I mean you only reduce the calories that you take in by six to seven hundred a day as opposed to just starving yourself and combine that with exercise, that is the most balanced way in which one should lose weight.

Dr. Meyerson: So big, rapid changes are to be nixed.

Dr. Stewart: Rapid changes are always harmful.

Dr. Meyerson: And if I, if I'm reading you correctly, in different words, I think you're not talking about going on a diet program and an exercise program. I think you're thinking about a long term, over decades modification of your life style for the long term; slow but steady really does win this race.

Dr. Stewart: Well I don't think it has to be over decades. I mean certainly --

Dr. Meyerson: Well no, no I -- what I mean by that is that good habits over decades.

Dr. Stewart: Well the habits need to be maintained over decades. I think that's the way to, to think of it. An individual can lose a substantial amount of weight just by making good behavior changes in three to four months as opposed to three to four weeks, but if they maintain those habits and maintain those habits over a lifetime, then the probability of keeping that weight off and staying healthy is, is very high.

Dr. Meyerson: Now I know your forte is not clinical nutrition, but I know you've looked at this a fair amount. Are there any diets out there that – I hate, I feel badly using the word diet. Are there any approaches out there that you've had success with the people that you counsel?

Dr. Stewart: Well I've had a very strong interest in the past couple of years in the low carbohydrate approach to eating. There are several reasons why that's beneficial. One is that you don't really have to focus so much on counting calories, but just learning which kind of foods to avoid and by avoiding carbohydrates, in the long term, you will take in less calories, but there are reasons that the type of diet you are on can make a difference. In the case of carbohydrate, low carbohydrate diets, you don't get this rapid rise in your insulin levels. You don't get a rapid rise in the triglyceride levels which all contribute to having high levels of insulin and high levels of triglyceride is actually part of the whole metabolic syndrome so that by avoiding very highly refined sugar foods, you can reduce the risk of diabetes and, and heart attack.

Dr. Meyerson: So just between today and tomorrow and without advocating any specific diet or book or approach, what you're telling me is that if I cut out free sugars, if I don't go to the bakery as often, if I, if I cut out maybe bread and rice and pasta and baked potatoes and candy, I could make an enormous inroad and maybe cutting even out, cutting out soda, for example or soft drinks of any sort that have the high fructose corn syrup. Just those few steps alone could eliminate enormous numbers of calories.

Dr. Stewart: That can make a tremendous difference and it, it always surprises me, particularly that you mentioned soda and the high fructose syrup -- these are the syrups that come from corn -- you know a can of soda, your typical Coke or diet -- I mean Pepsi, not the diet type which has zero calories, but your regular Coke, your regular Pepsi, whatever brand. I'm not really picking on any brands here. They have about a hundred fifty to a hundred seventy-five calories and there are people that might be drinking six, seven, eight of these a day and that's about half of what the calories that an average person should be taking in for the entire day.

Dr. Meyerson: So the first thing that they should do is get off the back side and walk, walk, walk, walk, walk, be more, be a little -- as active as you possibly can within the limits of your capability and then begin to take a look at what you're eating and where your calories are coming from. Is that right?

Dr. Stewart: Absolutely. And again, I picked on, I kind of -- we picked on soda here because that's kind of a very easy thing to change.

Dr. Meyerson: Now I want to spend just a, maybe thirty seconds more because you've done some research about -- does central abdominal fat have anything to do with either liver fat or what they call a fatty liver?

Dr. Stewart: Well fatty liver is another condition and it tends to be very prevalent, so there's very -- a high rate of it in people who are obese and this is the fat that, again you can't see. It's embedded within the liver and it, it leads to a condition called hepatic steatosis and this is the leading cause of liver psoriasis, cancer, liver failure and is very highly associated with heart disease and diabetes risk.

Now individuals who have high abdominal fat, again won't necessarily have high amounts of hepatic fat. We don't know why. They seem to be somewhat independent of each other, but if an individual is just obese in general, they're likely to have one or both sources of this invisible -- when I say invisible, I mean you can't see it. It's there. It's definitely there, you just -- you can't see it, but it's there and it's harmful and the best way to deal with it is to lose weight and exercise.

Dr. Meyerson: So if you're going to start on an exercise program, truthfully we do recommend checking with your doctor, making sure that the doctor gives you somewhat of exercise guidance an exercise prescription, if you will, so you know how much and of what type of exercise is safe and reasonable for you.

It is never too late to get back on a healthier eating style and to start picking those foods that are, are – as one of our colleagues, eat greens, beans and leans and there are a lot of wonderful food choices out there, but some of what Dr. Kerry Stewart has told us today should give us wonderful insight because so much of these diseases that we hear about are preventable diseases and even if you have had the first round of a heart attack or a threatened stroke or something like that, it's not too late for you to get control of all these things so that the second one doesn't happen.

For the Vascular Disease foundation, I'm Dr. David Meyerson with my guest Dr. Kerry Stewart, again Professor of Medicine, Director of Clinical and Research Exercise Physiology at Johns Hopkins University School of Medicine and as always, I'm Dr. David Meyerson.

   Thanks so much for listening.

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