Science Talk

Can Fat Be Fit?

In this episode, award-winning journalist Paul Raeburn talks about his article in the September issue of Scientific American, called "Can Fat Be Fit?" as well as another piece he wrote as a sidebar to a feature, about losing weight and keeping it off. Plus we'll test your knowledge of some recent science in the news. Websites related to this episode include;

Welcome to Science Talk, the weekly podcast of Scientific American for the seven days starting September 12th. I am Steve Mirsky. This week on the podcast: More from the September single-topic issue of Scientific American devoted to food, feast and famine. We'll talk with Paul Raeburn, author of the article "Can Fat Be Fit?".Plus, we'll test your knowledge about some recent science in the news. Paul Raeburn is an award-winning science journalist. He was the science editor for the Associated Press and for Business Week magazine and he is the author of books ranging in subject matter from space science to depression. In addition to the article on fat and fitness, Paul penned a sidebar to another article in the issue. The sidebar is called "Dropping Weight … and Keeping It Off." We spoke at his apartment in Manhattan.

Steve: Hi Paul. How are you doing?

Raeburn: (laughs) All right.

Steve: Great. Thanks for having me here [at your]place here. Let's talk about "Can Fat Be Fit?" is the title of the article, so that's an obvious good question for me to start with: Can fat be fit?

Raeburn: Well, I think, I wish the answer were yes. I would like the answer to be yes and certainly millions of Americans would like the answer to be yes, but what I found out looking at the studies and talking to people is that while it's always better to be fit than not fit. The basic bottom line—well, we'll go to right to the core of this thing—is that when you gain weight you have adverse health effects; now, again, it's certainly better to be riding your bike, if you are 20 pounds over weight than sitting around and getting more overweight, but those extra pounds are going to have consequences.

Steve: Now in the article, you talk about the study that came out a couple of years ago that caused a lot of controversy, where it was a meta-analysis of a bunch of other data and the resultant conclusion was, "wait a minute, these people who are somewhat overweight are living longer—have lower mortality—than the people that we think of as having normal weight", but then there was a lot of controversy and then some other studies in response to that study.

Raeburn: Yeah! That's right. People who were just slightly overweight in that study turned out to be a little healthier by various measures, and I don't want to give anything away here, but I was pretty happy with the results of that study myself and so were millions of others, of course, for obvious reasons. Now it may be—I tried to be very careful in the piece in Scientific American to say—that nobody has strictly disproven that study. The statistical things are very tricky and I wouldn't sit here and say that I can go through all the mathematical minutiae and analyze what's going on—far from it; I can't get into the nuts and bolts at all. It really requires a professional, and the evidence for that of course is that the professionals argue madly over these things about whose right and whose handling the statistics correctly, so we can't say that that study was, that was Katherine Flegal at the …

Steve: …at the CDC.

Raeburn: Study of Katherine Flegal at the Centers for Disease Control and we can't say flatly that that study was wrong, but there are many, many, many studies—in fact a whole history of studies—that suggest the opposite, which is basically that with every pound or two, you increase your risks a little bit and every pound or two you take off, you improve your outlook a little bit.

Steve: And you have quote from Meir Stampfer at the Harvard School of Public Health. It just says that other study is "complete nonsense" (laughs).

Raeburn: Yeah! Well, (laughs) he tactfully said, it was complete nonsense, yeah. That's what I meant about fighting over statistics. These things, they are very subtle; in his view obviously, the study was meaningless. Now, you know, we just want so badly to believe that being a little overweight is okay, you know, we eat these things up, so to speak, these kinds of results. And of course being a little bit overweight is far better for you than being a lot overweight. So everything is relative here, but you know, as I say, it would be nice, but there are a lot of questions about the study, a lot of questions.

Steve: You talk about three kind of easy—well, two easy and one slightly more complex—parameter[s] to determine whether you are getting a little out of control here, the BMI.

Raeburn: Right. BMI is a, it's a little bit tricky to do it in your head, but you can, all over the net, if you go into Google and look for "BMI calculator", you will find …

Steve: And BMI is…

Raeburn: It's your, it's a mix of your height and weight.

Steve: And it's Body Mass Index.

Raeburn: Body Mass Index—right, so it's just a way of figuring that, you know, obviously 150 is not overweight for some—you know, it's underweight for somebody who is six foot five and overweight for somebody who is five foot five. So, it factors in the height and weight appropriately. So, your BMI—the so called healthy range, for BMI—is between 20 and 25, or under 25, in that range. You know, many, many Americans have crept out of their range, particularly over the last 10, 20, 30 years; we're getting heavier. The other factor that—these come from Walter Willett at Harvard School of Public Health who has done a lot of this research—was that, you think about, for those of us who are adults now, so we were adolescents at a time when adolescents weren't having the problem with obesity that they are having now. So, the assumption is that when we are adolescents we were probably about at our correct weight, so think about what you weighed at age 20 and that's probably something like your ultimate goal of where you might want to try to get to; and by [the] same token, if you can remember what your belt size was at age 20, that's probably what you want to get back to.

Steve: I still have those belts.

Raeburn: Yeah! Yeah! (laughs)

Steve: They are aging nicely.

Raeburn: Well, that's because you are still the same as you were at, the same size you were at 20.

Steve: Well, they are in the closet waiting to get used again.

Raeburn: Yeah! That's right. We are all on that road. So, those are now, I would have to say, certainly in my case the idea that I would ever get back to what I weighed at 20 seems impossible; and you wouldn't catch me betting a lot of money that I will ever do it. But you know I would like to get closer, like a lot of people and, you know, it gives you something of a goal. What was also interesting about Walter Willett is that, you know, I think many people, if you say the normal range for BMI is between 20 and 25, then people get to, you know, 24.9, and they exhale, "Whew, you know, I've got where I need to be, I'm in the normal or the healthy range and so, I'm okay”. But there's a quite difference within that range; that is to say, if you had a BMI of 20—which is right at the bottom of the so called normal range—and you rose to 24.9, which is still in the normal range, you would quadruple your risks of diabetes, so that's all within the normal range. Now, that's from a very, very small risk of diabetes to it, to a slightly less small risk.

Steve: Right, it's still a small risk.

Raeburn: But that's right. But it reinforces the point that he makes—and that a lot of research has made—which is that, you know, the more you lose, the better off you are even if you are in the so-called normal range, if you can knock off a few more pounds, that's a good thing too. Now, I should say, you know, for some small portion of our listeners, I think it's always important to remember this. There are people who have eating disorders and problems and no matter—I mean, you can see them on the streets here in New York City—people who are clearly way below normal weight, way below where they should be, and so we want to exercise a little bit of caution. You don't want to lose weight endlessly to the point where you look like a stick figure, that's not healthy either. There is a point where it becomes very dangerous; in fact, people die from anorexia. So, you know, within reasonable ranges, the more you lose, the better off you are, but you don't want to make yourself ill by being really excessive about it.

Steve: Let's talk about BMI just for a moment. I realize that, for most people, it's probably a reasonable kind of figure to deal with, but for example, lot of professional athletes—world class athletes who are, you know, four percent body fat people, their BMIs would have—you think that they are obese. You know you look at one of these NFL running backs who is five-eight, 210 pounds, but it's solid muscle.

Raeburn: Right.

Steve: And I realize that doesn’t apply to most people, but doesn't the BMI break down under those kinds of extremes?

Raeburn: Yeah! Under the extremes it does. In fact the BMI does not take a kind of percent of body fat that you are carrying—percent of your weight that is body fat—and that's true and the reason is that the lead athletes, you know, in many sports develop so much muscle mass, that that throws it off; that's not going to be an issue for most of us, but it does come up sometimes in these discussions about whether overweight people can be fit, and it's easy enough, you know, a doctor can certainly measure your body fat mass. There are gadgets now that you can buy relatively inexpensively, some bathroom scales will measure your percentage of body fat at least to an approximation. So, if you really think you are in that category, if you really exercise intensely or play sports you know very actively, very regularly, you know, there are a few people who might be in that category, they might want to check that out because again. You know, you don't want to be losing, you don't want to lose muscle mass—muscle is good, you want to lose fat, that's the idea. I think for most of us, you know, we can stand in front of a mirror and we can tell what's fat and what's muscle. But certainly at the extremes, you know, it is desperate doubt.

Steve: If when you buckle your pants, the stuff moves around a lot.

Raeburn: (laughs) Yeah, that's not muscle.

Steve: It's not muscle. Speaking of lead athletes, there's a photograph accompanying the article, "Can Fat Be Fit?"I know you didn't have anything to do with choosing the photograph, our art department did. But it shows this, I mean, this guy is big and … yeah, he is (unclear 10:27)[overweight] and he is riding a bicycle and it's an example of the fact—and I've seen this on organized bike drives; you'll see some really big people on bicycles and they can do a 100-mile rides. It's not like a marathon. You will not see somebody a 100-pounds overweight completing a marathon under ordinary conditions, but you will see somebody carrying an extra 100 pounds doing a 100-mile bike ride occasionally. Now, what's great in this photograph for me is, this guy is riding the bike and he's got these incredibly expensive wheels on the bike, there are these spokeless wheels, carbon fiber, I think, I'm not sure. One thing, you know, this isn't a question of fat and fitness, this is more of a question of fat and performance, but I can guarantee this guy, that if he loses 15 pounds, he'll make up much more time than he will spend in all that money on the fancy wheels.

Raeburn: (laughs) Yeah! Well, what's easier to do, spend a thousand dollars on fancy wheels or lose 15 pounds? You know, sadly, I mean this is an area we can get into, too. You know, losing weight is not easy and for a lot of people it's going to be lot easier to ruin [burn] a thousand dollars and buy some wheels and [than] it is going to be to lose that 15 pounds.

Steve: Well, you just gave us a natural segue into the other piece that you have in the magazine. You have the sidebar in the Nestle piece in the magazine. We have an article by Marion Nestle called "Eating Made Simple" and your sidebar is about dieting. It's called "Dropping Weight…and Keeping It Off." And let me see if this is the quick summary: All diets work; no diets work. All diets work short-term if you are motivated and follow them; no diets work long-term.

Raeburn: Almost right, almost right. Yeah, that's true. It was an interesting study done recently in the spring that I used to lead off the piece out of [Stanford] and they looked at the Zone Diet, the Atkins Diet, they looked at the Ornish Diet…

Steve: That's a heart-healthy diet.

Raeburn: [The] Ornish Diet is a very low-fat diet; the Atkins and the Zone are more high-protein diets. And then they looked at a sort of government program, which is sort of the standard, you know, keep your fat low, low calorie and so forth, standard diet, that's typically recommended and, you know, most of the headlines at that time said, you know, "Atkins Beats the Standard Diet", you know, because the Atkins people lost a smidgeon—that's a scientific term—a smidgeon more than the people on the other diets, but in fact the author of the study who I talked to said the interesting point is people lost weight on all of these diets during the course of the study; you know in the five- to ten- pound range—modest weight loss, which does have health effects and is worth doing. But the problem, the study didn't go onto follow them longer, but many, many studies have shown that people do not maintain these kinds of weight losses that they get in diets, so you join Weight Watchers, you got whatever program you like or you buy a book and whatever the diet is, you start paying attention to what you eat; and over the first couple two-three months, you are going to lose five or ten pounds; [it] might take five or six months, but you are going to lose some weight. You probably eat healthier, whichever diet it is you are following, and you'll be on the road to better things; and then for a variety of reasons that aren’t entirely understood, people can't keep that up and gain the weight back. Now some of the, you know, the standard advice for this is, you know, don't use the 15-grapefruits-a-day diet; [that] is not going to do it, because you can't eat that for the rest of your life; you'll start to grow a thick skin and turn into a citrus fruit before you know it. But if, you know, so the standard advice is follow a good, you know, reasonably low-fat, low-calorie diet, stay away from the you know, reach for the fruit not the cupcake, and then you don't have to put a lot of thought into this to figure out what's the right thing to do, and then, you know, if you get into the habit of having, you know, an apple after dinner instead of a piece of apple pie, you know you are going to do better and that's something you can probably continue. An apple is an tasty thing, there is nothing extreme about, it's good. You just to have to develop a taste for that rather than the sweets, but even that advice for most people doesn't seem to work, so it's a bit of a quandary.

Steve: It's always instant gratification versus long-term gratification I think.

Raeburn: I think that's it, and, you know, the health benefits when, if you lose, you know for those people listening or reading the magazine, who've lost 10 or 15 or 20 pounds, people begin to feel better, they feel lighter on their feet, they feel they can walk more easily, they don't lose their breath going upstairs and so forth. You know, you get a bit of a benefit. If you lose five pounds, you probably don't feel a whole lot different. And let's be honest here: When we look in the mirror, the vanity factor is a factor too, and people want to, you know, if looking trim and looking fit helps people actually become fit, I'm all for vanity. You know, if that's a motivator, but, you know, losing five pounds isn't going to give you, you know, it's not going to put you on the cover of Men's Health. Can I mention a competing magazine, or should I not?

Steve: No, no…

Raeburn: So, you know, losing a few pounds isn't going to vastly improve the way you look, but, you know, you have to lose a substantial amount of weight. So I think that maybe—this is my own amateur psychologizing here—but that maybe part of the problem too is that, you know, as you say, you don't get instant benefits, although, you know, many people when they begin to diet, you know, say they feel much better within their first weeks or a month or two.

Steve: I will tell you, as a cyclist, if I drop five pounds—which I've done many times—if I drop five pounds, I will feel it climbing hills on the bike.

Raeburn: But you don't feel it walking to work in the morning or...

Steve: No, no—but under duress.

Raeburn: Under duress. Yeah! Yeah! That's right.

Steve: I can tell it's just much easier; and if you lose another five, it's just that much easier again.

Raeburn: Right, right. Which again, you know, that's another kind of secondary benefit of exercise. Now a day's cycling help[s] you keep in the excellent physical shape that you are in, but you know …

Steve: (laughs)

Raeburn: Right, exactly. It's radio, we can say anything.

Steve: Right. Right.

Raeburn: See, you know, it keeps you in good shape, but because you notice, if you've had a big meal or a bad weekend vacation, that it's a little tougher getting up those hills; that gives a little added incentive to drop that extra few pounds.

Steve: So, the kind of underwhelming but rock solid conclusion based on all these diet studies is that, you know, I wish I could tell everybody differently, but—you mentioned in the article—it's: eat moderately and get exercise.

Raeburn: That's the deal, that's the deal. Yeah and after extensive research and reporting, we come back to that old message, which is exactly what I said in the piece—that it's simple. We all know how to do it really. You don't need a lot of books and programs and things to figure out how to do this. As I said, the apple rather than the apple pie will do it for most of us, but it's sticking with that that's important and, you know, exercise is often overlooked by people on diets, I think. Very concerned about what they are putting in and not so concerned about what they are burning off, but exercise, you know, makes it easier. Somebody told me, if you don't exercise, then your diet has to be perfect and if you exercise, you give yourself a little [lee]way to have a bad night now and then—you go out, you know, for your run or your cycle or your walk the next morning and you get back on tracks.

Steve: Yeah! And it can be a[s] simple as a walk.

Raeburn: It can be as simple as a walk.

Steve: Just start [with]for a walk to get started.

Raeburn: That's right. That's right. Doesn't have to be [a] long time. You know, if you don't walk at all, walk for 10 or 15 minutes. If you walk for 15 minutes, walk for 20 or 30 minutes. Whatever it is, notch it up a bit and, you know, a lot of people who are not natural exercisers or natural athletes find that they begin to like the exercise and enjoy it and look forward to it. A walk in morning for half an hour can be a nice way to sort of settle your mind before you get into the office and face the chaos.

Steve: Paul, thanks a lot.

Raeburn: Sure Steve.

Steve: Paul Raeburn's article "Can Fat Be Fit?" is available free on our Web site,, and so is Marion Nestle's "Eating Made Simple" which includes Paul's sidebar "Dropping Weight … and Keeping it Off."And for more on Paul, check out his Web site,; that's spelt[spelled] p-a-u-l-r-a-e-b-u-r-n; and by the way, in a study of over 300,000 people that was published on September 10th, researchers found that for every five units that a person's BMI increased, the risk of heart disease went up 29 percent, and if they took blood pressure and cholesterol levels out of the measurements, the risk of heart disease still went up 16 percent, just based on the BMI increase. We'll be right back.

(Male voice: This is Paul and I'm a fan of this podcast. Today's podcast is brought to you by, the leading provider in spoken word entertainment. I use Audible when I'm planning a road trip. With over 35,000 titles, including Einstein by Walter Isaacson or A Short History of Nearly Everything by Bill Bryson, there are lots of books to chose from. But don't wait to go on a trip. Log onto and get a free audio book.

Steve: Now it's time to play TOTALL…….Y BOGUS. Here are four science stories; only three are true. See if you know which story is TOTALL…….Y BOGUS.

Story number 1: A man who enjoyed two bags of microwave popcorn a day for a decade was diagnosed with a condition called popcorn worker's lung, which includes scarring of the lung.

Story number 2: Researchers are making great strides in improving the surfaces of the insides of food containers to make it easier for you to get out the last dollops of, for example, ketchup or mayonnaise.

Story number 3: Rabies has been almost totally eliminated worldwide.

And story number 4: The mysterious disappearance of huge numbers of honeybee colonies has been linked to a viral infection.

Time is up.

Story number 1 is true. A 53-year-old Colorado man came down with popcorn worker's lung from inhaling diacetyl, the compound used to give the popcorn that butter flavor. The lungs' air sacs get inflamed and scarred. The guy'[s] home had levels of diacetyl similar to those found in popcorn factories. The good news is that the case of a consumer getting the condition has apparently convinced some popcorn makers to stop using the chemical, which for years has been afflicting workers at popcorn factories and in other industries using diacetyl.

Story number 2 is true. New coating should make it easier to get more ketchup or mayonnaise out of the containers. Sounds silly, but up to a fifth of some of the products you pay for get thrown out or washed away because the stuff sticks to the inside of the jar—and that makes recycling harder, too—but German researchers have developed a technique for applying thin films less than 20 nanometers thick to the inner surfaces of containers to make those surfaces more slippery. Examples of the new process will be presented at the International Trade Fair for Plastics and Rubber in Düsseldorf, the last week of October.

And story number 4 is true. Researchers trying to pin down the cause of the honeybee-die off that has decimated bee populations for the last year have found a connection to a virus. They did genetic analysis of healthy and diseased bee colonies and found evidence for the presence of a rare virus called Israeli acute paralysis virus. It's not definitive proof that the virus is causing the die off, but it's the first big break in the case. For more, check out JR Minkel's September 7th article on our Web site, called "Mysterious Honey Bee Disappearance Linked to Rare Virus".

All of which means that story number 3, about rabies being almost totally eliminated around the world, is TOTALL…….Y BOGUS. Because 55,000 people still die annually from rabies. However, canine rabies, the form of the disease that can be transmitted from dog to dog directly, has indeed been wiped out in the U.S., according to an announcement last week by the CDC. Unfortunately, dogs can still acquire rabies from other mammals such as bats, raccoons and skunks. And dogs, cats and cattle are still the domesticated animals that are most likely to get the disease. For more, check out the September 7th episode of the Daily SciAm podcast, 60-Second Science.

Well that's it for this edition of the weekly SciAm podcast. Check out numerous features at our Web site, including the blog, "Ask the Experts", and the "Latest Science News," all at; and you can write to us at For Science Talk, the weekly podcast of Scientific American, I am Steve Mirsky. Thanks for clicking on us.

Websites related to this episode include;

Share this Article:


You must sign in or register as a member to submit a comment.

Give a Gift &
Get a Gift - Free!

Give a 1 year subscription
as low as $14.99

Subscribe Now! >


Email this Article