When Packing On Pounds, Location Counts

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IRA FLATOW, host:

Up next, as I say, something more mundane but a mystery, a mystery, a great mystery nonetheless: fat. Why does fat settle on your hips or your belly instead of someplace else? And why does it actually act differently once it gets there?

You might think of fat as just inner blubber that hangs out in unwanted places. You might call it a muffin top, innertubes, beer bellies. But it's a lot more complicated than that. Fat's a sort of organ with a lot of biological functions that - well, we really don't understand all the things that fat can do.

One thing scientists do understand, though, is that for people with heart disease, the waistline seems to be a particularly dangerous place for fat to settle, and that belly fat seems to increase the risk of death. That research appears this week in the Journal of the American College of Cardiology.

As for where the fat goes, well, another study, in the journal Obesity, found that fat that is sucked away from your thighs and your hips, you know, using liposuction, that fat came back, pound for pound, and it settled in the belly. Why?

And if liposuction is taking good fat out of fat places, or it's taking out the fat of the good places, only to have it return to bad places, could liposuction be a risk to your health, if you're having it done, moving it around, and it winds up in a bad place?

We've got a lot to talk about, and if you want to chew the fat with us, you can give us a call. Our number is 1-800-989-8255, 1-800-989-TALK. You can also tweet us, @scifri, @-S-C-I-F-R-I, or talk to folks over there in our Facebook page at scifri and on our website at sciencefriday.com.

Let me introduce my guests. Dr. Francisco Lopez-Jimenez is a cardiologist at the Mayo Clinic in Rochester, Minnesota, and he's also professor of medicine and director of the Cardiometabolic Program there. Welcome to SCIENCE FRIDAY.

Dr. FRANCISCO LOPEZ-JIMENEZ (Mayo Clinic): Thank you.

FLATOW: You're welcome. My other guest is an author on that paper about liposuction. Dr. Robert Eckel is past president of the American Heart Association. He's also professor of medicine at the University of Colorado Anschutz Medical Campus in Aurora, Colorado. Welcome back to SCIENCE FRIDAY, Dr. Eckel.

Dr. ROBERT ECKEL (University of Colorado Anschutz Medical Campus): Thank you very much, Ira.

FLATOW: Let's talk about this fat study. Tell us what you found in this new survey of studies of heart disease and fat. Belly fat is worse than other kinds?

Dr. LOPEZ-JIMENEZ: Yes, well, what we found was that patients with coronary diseases, specifically patients who have had a heart attack, when we measure body weight, BMI, we prove that those who were heavier had actually a better prognosis than those with normal weight, whereas when we divided patients according to the fat distribution, those who had more fat in the waist or those who had a bad fat distribution, meaning that the waist was bigger than the hip, they had higher mortality than those with normal distribution.

FLATOW: And so the fat that was around your waist was more threatening to your life.

Dr. LOPEZ-JIMENEZ: Yes.

FLATOW: And tell us, just for definition sake: What is belly fat? Where is that found?

Dr. LOPEZ-JIMENEZ: Sure. Well, belly fat or abdominal fat is defined as having more than 40 inches of waist circumference for men or more than 35 inches for women. And that belly fat is usually a combination of the fat that is mixed with the guts and also the fat that is under the skin in the abdominal area.

FLATOW: So you know, muffin tops, innertubes, those would be the descriptions of them?

Dr. LOPEZ-JIMENEZ: That would be - right, yes.

FLATOW: Dr. Eckel, tell us about this liposuction study. This sounded like it had unusual answers in the study.

Dr. ECKEL: Well, we asked the question very simplistically, whether body fat is defended. I do a lot of research in obesity and the regulation of body fat, and we've known for a long time that people have trouble losing weight. But it's even more difficult after they lose weight to kind of keep the weight off.

So then we turn to the animal, and studies done by other people around the world have shown that when you take fat out of an animal, ultimately they put the fat back in other places. So in other words, liposuction in the animal is not very successful in reducing total body fat.

So we had kind of a pilot study done nearly 20 years ago now here at the University of Colorado where in fact we removed some fat by liposuction and let these women kind of go their free course over a year.

And half of them regained the fat and half of them didn't. And it seemed like the ones that didn't regain it became physically more active and actually tried to lose additional weight.

So we said: Gee, we need to do a study that's really a randomized control trial, where we recruit women who want to lose their body fat by liposuction and then randomize them into surgery versus no-surgery.

So Dr. Terry Hernandez(ph) and I have worked together on this project over the last seven or eight years, and the study was conclusive, that if you remove fat from normal-weight women - keep in mind, these are not like Dr. Fernando Jimenez's patients, but in fact these patients, in fact, are not patients. They're normal women who in fact don't like their saddlebags.

So we randomized them into a group with surgery and without surgery, and little did we know, but ultimately all the fat came back within one year after the liposuction. But it did not come back where it was taken off.

In other words, these women were very happy with the cosmetic effect. It's just that now they weighed the same a year later, but in fact it was distributed in the abdomen.

FLATOW: And which is - it sounds to me from the studies, it's a more dangerous spot to be in.

Dr. ECKEL: It is. And you know what? We don't know, Ira, at this point as to whether or not that's going to pay dividends going down the road. In other words, right now these women remain healthy, and they weigh the same as they did, but the fact that the surgery was done in an area below the waist means that maybe if they gain more fat as they get older, that fat can't go downstairs, it has to go upstairs.

So that's an answer that really is unclear at this point in time and will require, I think, additional studies to address.

FLATOW: Now, I found one interesting aspect of your study is that when you divided the women into the groups, ones that got the liposuction and ones that didn't, and you told them when the study was over, the women who did not get it, they had the option of getting this liposuction themselves if they wanted to, but yet that you told them the fact would come back, half of them still went ahead with it.

Dr. ECKEL: Well, right. I think a fair percentage of the women who were in the control group and did not have the surgery, they were willing to go ahead after the study was completed, even knowing that the fat might come back.

So ultimately I think this again remains a cosmetic procedure, and if a woman is unhappy enough where her fat's at, we know that we can take care of that using a plastic and reconstructive surgeon.

FLATOW: Dr. Lopez-Jiminez, you mention a little bit of a nugget that you mentioned on your opening statement. I want to go back to it a little bit. And that touches on some previous studies where you found that among people with heart disease, they were actually better off the higher their BMI or their body mass index was than - and that seems to fly against what we keep hearing about measure your BMI and use that as a way to regulate how much you weigh. But you're saying that's not as good an indicator anymore.

Dr. LOPEZ-JIMENEZ: Yeah, that's correct. And that has been called as the obesity paradox because that's really a paradox. It's totally different than what we would expect or different than what we see in people without heart disease.

And there has been many different theories on how to explain the results because it was really disturbing to see that, especially in these days that we are trying to promote healthier lifestyles and to avoid the obesity epidemic. And we didn't want patients to feel comfortable being just overweight and having heart disease.

And so the explanation is - I don't think anybody has a real explanation, and some people went from the very simplistic approach of just discounting those findings by saying that, well, those with heart disease who have normal weight are likely sicker and more likely to have cancer or other conditions that will make those people to live shorter.

Well, most of those studies adjusted for many of those factors that would explain that, and still, even after controlling for those factors, the paradox continue.

So actually the main hypothesis of this latest publication was: Will the same paradox stand for central obesity? I mean, is it that fat doesn't matter at all in people with heart disease, or is it that the distribution is what truly matters?

FLATOW: Dr. Eckel, in reading research, it was fascinating to me to learn that fat is not just some ugly little mass of cells there, but it actually is very active all the time. Is it not?

Dr. ECKEL: Yeah, that's true, Ira. Adipose tissue is really an organ. It's just like the liver or the spleen or the heart or the lungs and carries out a function.

And in the past it was just thought that adipose tissue or fat was a depot for calories and that many a times those were excessive. And there's no question that if you don't eat for a long period of time, you depend on your adipose tissue for fuel, because it releases all that fat, and that fat can be used for fuel.

But in the setting of adipose tissue physiology, we know that the adipose site releases lots of hormones and peptides. It can communicate information to other organs. And I think - we think in part that once the fat's removed surgically by liposuction, the brain senses the deficiency, and it makes up for that by modest and subconscious changes in behavior. So we think this is a real regulatory pathway.

FLATOW: So it's not getting signals anymore from the brain. The brain says, uh-oh. Fat's missing. Make some more of it.

Dr. ECKEL: Correct. And I think this really feeds into a lot of other aspects of adipose tissue physiology. For instance, the first menstrual cycle on a young woman or a girl occurs at a time when her percent body fat reaches a certain level. And if she becomes overly active and loses too much fat, she quits ovulating and menstruating. So we know that adipose tissue's probably important to the reproductive access. And so this is another example that fat's defended.

Now, again, we approached this initially from the obesity perspective, because people can't lose weight very easily and keep it off for a long time. Now we've shown, even in normal weight women, that taking it out surgically, it's all back by a year.

FLATOW: It's interesting because, you know, we keep hearing that girls, young women are having their menstrual cycles earlier in their life. And we also hear that our kids are getting fatter at a younger age. Could this fat then be triggering menstrual cycle at an earlier age?

Dr. ECKEL: Absolutely. And this change in the age of menarche - which is the first menstrual period - really has gone down by a year and a half or two over the last several decades. And we think that's really adipose tissue-driven - too much fat, too early. And we know kids are experiencing really the same obesity epidemic we see in adults.

(Soundbite of laughter)

Dr. ECKEL: Not a good message.

(Soundbite of laughter)

FLATOW: Wow. Do certain diets affect where the fat goes?

Dr. ECKEL: You know, I don't think, Ira, we can say anything about diet composition and where fat goes. We know that, clearly, excessive intake in terms of eating more than you burn's going to accumulate extra fat. But where it goes - particularly in a woman. Why does it - why do some women put it in the pelvis, and other ones put in the abdomen?

And back to Dr. Lopez-Jimenez's findings, we know if she puts it in her abdomen, she's got a greater risk of heart disease, and likely all-cause mortality. But if she puts it in the pelvis, actually, from a cardiovascular perspective, we don't think that that risk is very high. It's probably not much higher than, in fact, being lean. And I think his data kind of speak to that.

But in men, you know, as we gain extra weight, we don't have much choice, do we? It all goes around the waist and we pay the price for that, I think, in terms of heart disease risk.

FLATOW: Dr. Lopez-Jimenez, any comments on that?

Dr. LOPEZ-JIMENEZ: You know, well, there are some - there are a few studies trying to prove whether or not particular types of food or so-called macronutrients are more likely to cause central obesity, and that's - those studies were triggered, I think, because of this general idea that high sugar or high carbohydrates can cause that.

The results haven't been really consistent. And I concur with Dr. Eckel that it's something that, really, nobody knows. And I think, really, this opens a lot of room for more research to determine what is the (unintelligible) causes central obesity. I mean, there are - there is strong evidence that genetic factors play a role. For example, Hispanics are more likely to develop central obesity than other ethnicities, but is that just because of genes, or is that because of a particular dietary pattern is still yet to be determined.

FLATOW: Hmm. Let's see if we can get a quick phone call from Melissa in Sun Valley, Idaho.

Hi, Melissa.

MELISSA (Caller): Hi, Ira. Thank you so much for taking my call. And thank you.

FLATOW: You're welcome.

MELISSA: My question was: I have been taking anatomy classes for a while, and our teacher mentioned something in regards to cholesterol and the placement of fat on your body, depending on if it's abdominal or if it's pelvic, as you were saying, and what difference that makes with deposition for LDLs and HDLs. Because we were taught that, basically, you have higher risks of HDLs in abdominal fat.

FLATOW: You have a higher rate of HDL in abdominal fat. Is that what you're saying?

MELISSA: Yeah. You have a higher risk of bad cholesterol...

FLATOW: The good...

MELISSA: ... the, quote, "bad cholesterol" if you hold it in your abdomen...

FLATOW: Right.

MELISSA: ...and therefore have higher risk of heart disease. So...

FLATOW: Let me just remind everybody that I'm Ira Flatow. This is SCIENCE FRIDAY, from NPR.

Dr. Eckel, any response to that?

Dr. ECKEL: Yeah. I can respond to that. This is an area that's been really well-investigated and, unfortunately, the information that she has is not accurate. In fact, women who put more - and men, too - more fat around the abdomen actually have lower levels of HDL, which is the good cholesterol. And we think that's one reason the risk for cardiovascular disease may be higher. So the opposite is true. So, more abdominal fat, the lower the HDL. And this is really a fairly predictable finding.

FLATOW: And what about the theory that you are what your genes say you are? And if your body genes said that you're going to be a certain weight and a certain fat, you can go - you can yo-yo up and down on the weight scale, but it's going to settle on the same place all the time.

Dr. ECKEL: So, Ira, there's no question that genetics play a large role in terms of what someone's ultimate weight is going to be. But I think the set point, the idea that we all have genetically programmed, a certain weight that we're going to achieve, is really false reasoning from the data.

I mean, the obesity epidemic we're experiencing right now really is an impact of the environment on the gene pool. So, yes, weight runs in families and it is genetically related, but when we eat too much and exercise too little, we're heavier as a population. So I like the term settling point, because it really relates to the interaction between the environment and the genetic predisposition.

FLATOW: And, Dr. Lopez-Jimenez, what is the - what should our waistlines be to be healthy? What should be measure them to be?

Dr. LOPEZ-JIMENEZ: Oh, that's an excellent question. Well, currently, we just - those cutoffs that I mentioned before - so less than 40, you know, inches in men and less than 35 inches in women right now will qualify as, quote, unquote, "normal waist circumference." However, it seems like different people might require different cutoffs for calling the waist circumference normal.

And so, so far, we know, for example, that people from an Asian background may develop significant abnormalities in their cholesterol and blood sugar, even when the waist circumference is, indeed, 34, 35 inches. So even though we all know that when the waist circumference reaches the 40 inches in men or 35 inches in women is definitely abnormal, at least here at the clinic, we try to tell patients that -try to stay away from those cutoff numbers because most likely...

FLATOW: Yeah.

Dr. LOPEZ-JIMENEZ: ...in the future we may call those numbers abnormal, as well.

FLATOW: All right. We're going to - we have to run out of time here, but I want to thank both of you for taking time to be with us.

Dr. Francisco Lopez-Jimenez, a cardiologist at the Mayo Clinic, and Dr. Robert Eckel, past president of the American Heart Association, professor of medicine, University of California, Anschutz Medical Campus in Aurora, Colorado.

Thank you for taking time to be with us today, gentlemen.

Dr. ECKEL: OK. Thank you, Ira.

Dr. LOPEZ-JIMENEZ: Thank you.

FLATOW: You're welcome.

We'll be right back after this break to talk about viruses. Don't go away.

(Soundbite of music)

FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY, from NPR.

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