The Fallacies Of Fat In his new book Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease, endocrinologist and obesity doc Robert Lustig deconstructs the mythology of fat. He says exercise, for all its benefits, won't help you shed pounds--and that fasting only worsens weight gain.

The Fallacies Of Fat

The Fallacies Of Fat

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In his new book Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease, endocrinologist and obesity doc Robert Lustig deconstructs the mythology of fat. He says exercise, for all its benefits, won't help you shed pounds—and that fasting only worsens weight gain.


This is SCIENCE FRIDAY. I'm Ira Flatow. This isn't going to take you by surprise, but America is fat. One in three adults is obese. For kids, it's one in six. But don't forget the infants. Doctors say there's now an obesity epidemic among six-month-old babies. And if you think you're safe because you're thin, consider that up to 40 percent of thin people have metabolic syndrome, in other words, on the road to type 2 diabetes, even if they can't tell by looking in the mirror.

My next guest says that some of the reasons we are fat is because we've been sold a bill of goods about what and how we should eat. For example, he says the health-conscious among you may opt for juice over soda. In fact calorie-for-calorie, 100 percent orange juice is worse for you than soda. He says the corollary to a calorie is a calorie is the mantra: if you'd only exercise, you'd lost weight. Not only is this wrong, he says, it's downright detrimental.

He goes on: the largest percentage of your calories is burned while sleeping and watching TV. And finally last quote, a standard six-ounce Yoplait yogurt has 11 grams of added sugar. So when you consume a Yoplait, you're getting a yogurt plus eight ounces of Coca-Cola.

Robert Lustig talks about all of these factors and what he says are some common misconceptions about fat and dieting in his new book "Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease." If you think a calorie is just a calorie, he might have you rethinking that. Let me introduce him.

Robert Lustig is author of "Fat Chance." He's also professor of pediatric endocrinology and endocrinology at the University of California, San Francisco and heads the obesity program there. He joins us from KQED in San Francisco. Welcome back to SCIENCE FRIDAY.

DR. ROBERT LUSTIG: Thank you so much, Ira, pleasure to be back.

FLATOW: You're welcome. You make such bold statements in this book. It's bound to make some people very angry.

LUSTIG: You're telling me.


LUSTIG: Although I have to tell you the food industry has had that book out for, what, two, two and a half weeks since it's been released, and I'm waiting for the onslaught and haven't seen it. And I think maybe the reason is because it's true.

FLATOW: It's true. You know, there's something that came out yesterday released from Harvard. Let me start here because just - hot off the press, as they say, from the Harvard School of Public Health. Maybe you read this. And it talks about one of the most widely used industry standards, the wholegrain stamp. Actually identified grain products that were higher in both sugars and calories than products without the stamp.

LUSTIG: Absolutely, and to be honest with you, wholegrain doesn't mean much. If you actually look at the USDA definition of wholegrain, basically what it means is you start with a whole grain, that is the starch in the inside, the kernel, or the husk or the bran on the outside, and then whatever you want to do with it is perfectly fine. It's still wholegrain.

So if you pulverize it and add sugar to it, hey, it's still wholegrain because that's what you started with. But you know what? All the benefits that you get from wholegrain are gone as soon as you pulverize it. So, you know, what it means is irrelevant because the definition is not helpful.

FLATOW: So you mean when I see a wholegrain bread made with let's say 100 percent of wholegrain wheat or flour, it's really not much better than regular white flour because it's been pulverized?

LUSTIG: Exactly. When you look at true wholegrain bread, that's like German fitness bread, with the nuts and the seeds, and it's really dense, that's a very different kind of bread than, say, what you have commercially available, where they talk about, you know, double fiber and this and that. A lot of the fiber that they tout in these breads is actually added soluble fiber, such as cilium and things like that.

Now you need those soluble fiber molecules, but you also need the insoluble ones. You need the cellulose. You need the stringy stuff. You need the hard stuff because the two together actually help you form a barrier on the inside of your intestine. I liken it in the book to what happens with the hair-catcher on your bathtub drain.

So it's this little plastic latticework with little holes in it. So if you let the water run, the water goes down the drain. But if you take a shower, and there's hair coming, you know, the hair gets caught, and then you've got a stopped-up drain. Same idea here. The insoluble fiber is the plastic latticework. The soluble fiber is the hair getting caught in the holes. And then when you have the two together, you have a real barrier, and what that does is it reduces the rate of flux, the rate of absorption from the gut into the bloodstream so that your liver can actually handle the onslaught of all those calories.

And so you end up doing the right thing with those calories instead of the wrong thing, which is making liver fat out of it. So when you consume the two together, you're good. Problem is, that's not what the food industry is selling you.

FLATOW: One of the things - let's talk more about fiber because you mentioned that one of the worst things we can do with our fruits and vegetables is to put them through the juicer because that wrecks the whole...

LUSTIG: Right, for the same reason.

FLATOW: For the same reason.

LUSTIG: Exactly. So basically when you put juice in a juicer, you're sheering the insoluble fiber to smithereens. The soluble fiber will still be there, but, you know, you need that scaffolding, that latticework to be able to generate that gel that's on the inside of the intestine. You can actually see on electron microscopy the gel that forms on the inside of the intestine.

And what that does it is it number one prevents the absorption, number two it allows a lot of the calories that you're consuming to be delivered further down the intestine so that the bacteria in your intestine will consume it instead.

Perfect example: almonds. You consume 160 calories in almonds. How many of those do you absorb? It turns out 130. Thirty of those calories are going to get metabolized by the bacteria in your intestine because the fiber in the almonds will deliver more of the nutrient down the intestine so that the bacteria can get it.

And that's good because that means you actually absorb fewer calories than you eat. Again, a calorie is not a calorie. So fiber is one of our - the best things the best things that we can do for ourselves. Fiber is the stealth nutrient. Fiber is maybe the single most important thing we've got in our natural food diet, and of course fiber is the thing that the food industry removes for its own purposes.

FLATOW: 1-800-989-8255, talking with Robert Lustig, author of "Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease." We've been hearing a lot about high-fructose corn syrup as contributing to the obesity epidemic, and one chapter of your book is called "Fructose: The Toxin."

And you write: Face it, we've been fructd(ph).


LUSTIG: I'm glad you said it and not me.

FLATOW: I had my finger on the button in case it didn't come out right.


FLATOW: But what do you mean by that? I mean, explain the different kinds of sugars and how the corn syrup fits in there.

LUSTIG: Sure, absolutely. So there are monosaccharides, meaning single molecules, and then there are disaccharides, meaning combinations of two molecules together. The monosaccharides are the following three: glucose, and glucose is important, and your body will make glucose if you don't take it in because it's so important because every cell in your body, in fact every cell on the planet, can metabolize glucose for energy. Glucose is the energy of life. Glucose is, for lack of a better word, necessary.

Then you have galactose. Galactose is the monosaccharide, the single molecule that's found in milk sugar. Now unless you have a disease called galactosemia, which I help take care of, which is about one in 10,000 babies, which will kill you by age two months if you don't diagnose it, your liver will turn galactose to glucose in about a nanosecond. So galactose is essentially glucose for the overwhelming majority of the population.

Obviously those who have lactose intolerance, you know, can't consume galactose because, you know, they can't absorb it, and that's a different issue but not the one we're talking about right now.

And then there's this other third molecule called fructose. And fructose is the sweet part of table sugar. It's the molecule we seek. We love fructose. We think fructose, you know, hung the moon. We think that any food that has sugar, fructose, in it is a safe food to eat, and that is actually built into our DNA. It is a Darwinian precept because there is no foodstuff on the planet that is both sweet and acutely poisonous.

This was the signal to our ancestors that any given food was good to eat. So we love this stuff. Think about it this way: You got children?


LUSTIG: How many times did you have to introduce a savory food to a baby before they would accept it? On average 13 times, that's what science says. But if the food is sweet, how many times? Just once. We are programmed to like the stuff. Now you put glucose and glucose together, that's called maltose, that's what's in beer.

You put glucose and galactose together, that's lactose, that's what's in milk. And then you put glucose and fructose together, that's sucrose or table sugar. Everybody understand the different kinds now. So we have six different compounds we're talking about when we talk about sugar. But I'm only talking about the sweet stuff. I'm talking about sucrose or high-fructose corn syrup, which is basically one glucose, one fructose, it's just made from corn. There is an enzyme process that turns glucose into fructose. It's still half-and-half, one-and-one, and that's why it's irrelevant.

They're the same. Table sugar, cane sugar, beet sugar, that's what the whole world has. High-fructose corn syrup is only available in the United States, Japan, Canada and very limited exposure in parts of Europe. And guess what? The whole world now has obesity and metabolic syndrome.

So it's not about high-fructose corn syrup per se. The reason high-fructose corn syrup is such a problem is because it's cheap. It's so cheap that it found its way into foods that never had sugar before. It found its way into salad dressings. It found its way into pretzels. It found its way into hamburger buns. It found its way into hamburger meat, ask Taco Bell what they put in their meat.

Bottom line: We are gorging on the stuff because it is now cheap, and in 1973 when DuPont invented the two-liter bottle, now we have the perfect fructose delivery vehicle, and look what's happened to obesity and metabolic syndrome since.

FLATOW: And fructose makes you want to have more of it, doesn't it?

LUSTIG: That's right, and there was a paper that just came out last week, it's gotten a lot of press, from Yale, Journal of the American Medical Association, showing that fructose doesn't cause changes in cerebral blood flow like glucose does, and it doesn't cause satiety like glucose does, and it doesn't change the hormones that regulate energy balance like glucose does.

So glucose is, for lack of a better word, good. And fructose, for lack of a better word, is not.

FLATOW: All right, we're going to take a break and come back and talk lots more with Robert Lustig, author of "Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease." Our number, 1-800-989-8255. You can tweet us @scifri. Get into the conversation. Do you agree with Dr. Lustig? Have you got stuff you'd like to talk about? We'll be back right after this break.


FLATOW: This is SCIENCE FRIDAY, I'm Ira Flatow. We're talking about food and nutrition with Robert Lustig, author of "Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease." So much to talk about. I don't want to get stuck on fructose because there's a lot more stuff in your book. But I can't avoid it because it's a topic of discussion. And some of your...

LUSTIG: Everybody wants to know about it.

FLATOW: Yeah, some of your critics even like to point to the fact that we're consuming less high-fructose corn syrup and added sugars today, but we're still getting fat. How do you respond to that?

LUSTIG: Absolutely. Well first of all, we are consuming a little bit less than we were, say, a decade ago. A decade ago, we were consuming 140 pounds of sugar per year per person. We are right now at 130 pounds. So yes, we have cut back slightly. The problem is that the data suggests that our bodies can only process approximately, I would say, somewhere between 50 and 65 pounds of sugar per year based on calculations that are related to what we do with alcohol, and fructose and alcohol are basically metabolized by the liver pretty much the same.

And that was sort of the thing that got all the attention was the analogy between the two. So we are still about double over our allotment, and that's the problem. The problem is that even though we have cut back slightly because diet sodas have increased their appeal. Currently in America, 42 percent of all beverage - you know, beverages made by the soda companies are now diet, so that has reduced total sugar consumption slightly - it's not nearly enough. And we are still way over our threshold.

FLATOW: So what's the antidote to this?

LUSTIG: Well, the antidote, unfortunately, in so many public health venues, and this is a public health crisis, Medicare will be broke by the year 2024 unless we get a handle on this, and there is no drug target for metabolic syndrome, bottom line, the answer is reduce availability. And that of course gets everybody's hackles, you know, up.

The whole concept of, you know, the libertarianism, keep your hands out of my kitchen, you know, don't tell me what to eat. Well you know what? We've already been told what to eat because of the 600,000 food items that are available in the American grocery store today, 80 percent of them are laced with added sugar. This is work from Barry Popkin at University of North Carolina.

Bottom line is you've already been told what to eat. You don't have a choice about what to eat. Your choice has already been co-opted. So when this comes right down to it, it's really who do you want in your kitchen. Do you want the government, who will take away your wallet and your freedom, or do you want the food industry, who has already taken away your wallet, your freedom and your health? That's your real choice.

FLATOW: Let's go to Hannah(ph) in Napa, California. Hi Hannah, welcome to SCIENCE FRIDAY.

HANNAH: Hi, thanks for taking my call. You know, I really have always tried to eat very healthy, but it wasn't until I developed gestational diabetes that I realized how incredibly complex it is and how much misinformation there is out there, particularly around sugar. Now that I have an infant, a six-month-old, I have other children, but it's just been since having gestational diabetes that I've learned about this.

But now that I have a six-month-old, and I'm trying to, you know, introduce solid foods - you can hear here in the background there - what about the baby cereal that's touted as wholegrain, organic? What - following your recommendations, Dr. Lustig, how do you feed a baby healthy solid food?

FLATOW: Thanks for calling, Hannah. We'll let you get back to your kids.

LUSTIG: Excellent question. The fact of the matter is that even baby formula is laced with sugar. The formula Isomil is lactose-free. What do they substitute? They substitute sucrose. Coca-cola is 10.5 percent sucrose. You know, Isomil is 10.3 percent sucrose. And there is sugar in virtually all of standard baby foods, and the reason is because that way the kid will eat it.

So we have this big issue about whether or not this is a good thing or not. Obviously parents want their kids, you know, to eat. The question is: Is this the best way to get them to do it? There's a toddler formula called Enfagrow, and basically what it is, it's a toddler milkshake. It's enormously chock full with sugar. And the company that makes it...

FLATOW: So what's a mother to do? Can you make your own food, or is there something...

LUSTIG: Yes you can, of course you can. What do you think happened before there was Gerber? What do you think happened before there were all of these, you know, baby food companies. Yes, you can. What I think the baby food companies need to do is they need to cut back on the added sugar. I think that the entire food industry needs to cut back on the added sugar. The problem is they have no impetus to do so.

FLATOW: But with concerned mothers like Hannah, would there not be a market for something like that they might take advantage of?

LUSTIG: Well, let's see. I'm waiting to see whether or not enough education of the public will actually put pressure on the food industry to do so.

FLATOW: And let me to go Ellen(ph) in Oakland. Hi Ellen, welcome to SCIENCE FRIDAY.

ELLEN: Hi, thank you. Dr. Lustig, I am a huge, huge fan of yours.

LUSTIG: Thank you.

ELLEN: I don't understand why scientists sometimes joke about this, about your research. But here is my question: I'm actually a nurse practitioner, and I'm addicted to sugar. It's sad but true, totally addicted. What would be your suggestion for getting somebody off sugar? I mean obviously you can say stop eating it, but as you know if you have an addiction, that's easier said than done.

FLATOW: All right, Ellen, thanks for calling.

LUSTIG: It's a great question, and to be honest with you, I wish I had, you know, sort of the easy, you know, off-the-cuff answer. We know from other addictive substances that because the dopamine receptors in the reward center are down-regulated by whatever that substrate is, and it can be nicotine, alcohol, heroin, cocaine, amphetamine, it takes three weeks of abstinence for those dopamine receptors to come back.

And the cravings still stay for many, many months, even sometimes years afterwards. This is a major problem in addiction is how do you deal with those. So how do we deal with addiction with any other substance? The answer is: Number one, cold turkey; number two, there are some medications that can be used, for instance, say, Wellbutrin is used for smoking, and there are some other things you can do. Ultimately the best way to do it is to wean yourself off.

Now how do you wean yourself off sugar when everything that's out there contains it? That's the problem. So we can't get kids off sugar. We also can't get kids off sugar in my clinic because the parents are addicted. So I've got two patients, you know, the kid and the parent.

You know, the kid may want to do the right thing, but the parent won't let them because, you know, keep away from my cookies. So it's a real - it's a major problem.

FLATOW: Let me go into one of the most interesting and most surprising parts of your book is the chapter on exercise, where you write, quote, "there is not one study that demonstrates that exercise alone causes significant weight loss." And the clincher is: The largest percentage of your calories is burned while sleeping or watching TV.

LUSTIG: Absolutely, and I'm not even the first person to say that. You may remember a time magazine cover article about three years ago called "The Myth of Exercise." They said it way before I did. The fact is that exercise does not cause weight loss.

What does exercise do? By the way, exercise is the single best thing you can do for yourself. So I am not in any way, shape or form demeaning exercise. I think exercise is the best antidote for anything that's wrong. So, you know, please don't call in and say, you know, Lustig says exercise is useless, not at all.

What does exercise do? What's the real value of it? Here's what it is: Exercise builds muscle. And muscle make mitochondria. And mitochondria are where the energy is burned. So if you have more mitochondria, that means you are going to have less chance of overloading those mitochondria and turning that excess foodstuff, in particular fructose, into liver fat.

So you can keep your liver, you can keep your muscle insulin-sensitive. You can keep your insulin levels down. And it's all about the insulin. Everybody thinks it's about the calories: absolute garbage. It's about the insulin. It's the insulin, stupid. And if you don't believe me, Jim Johnson from the University of British Columbia just published a paper two months ago in cell metabolism where he has a beautiful animal model where they can regulate the amount of insulin that the animal makes, you know, from scratch, and whatever that insulin level is, that's how much that animal gains.

So there are people who, you know, get the fact that a calorie is not a calorie. There are people who understand that things that make your insulin go up are the things that are going to make you gain weight. Perfect example, Gary Taubes has, you know, been saying this now for 10 years. That's exactly right.

So this is where Gary and I actually agree. It is the insulin, stupid. And there are a lot of people who understand that and believe that, especially endocrinologists. But the problem is that's not what the food industry and that's not what the government wants you to believe.

FLATOW: 1-800-989-8255. Interesting tweet from Miranda, who writes: Can I still have beer if I cut out other processed sugars? I'm from Wisconsin, after all.


LUSTIG: Well, I used to live in Wisconsin. I was a faculty member at the University of Wisconsin for five years, and you know, I like a beer every once in a while too. The problem with alcohol is that normally it has a J-shaped curve. A little bit of alcohol is good for you; a lot of alcohol, obviously, is not. And there's a nice, you know, place in the middle.

The problem with beer and also shochu, which is a Japanese carbohydrate-containing alcoholic beverage, is that there's no edge on the J. It's basically a straight-up curve. And the reason is because beer is both glucose and fat, because alcohol gets metabolized like fat, as fructose does, at the same time.

And so the glucose in the beer will get metabolized to glycogen or liver starch, and the alcohol will get metabolized as fat, thereby overwhelming your liver mitochondria, thereby causing the same level of insulin resistance. So of the various alcoholic beverages that are out there, I would say the beer is not the best choice to tie one on with.

FLATOW: As wine or spirits?

LUSTIG: Wine is much better.

FLATOW: Same thing?

LUSTIG: Well, as long as you do them, you know, as everyone says, in moderation. Hey, I partake as well. You know, bottom line is everything in moderation. The problem is that the food industry has not allowed us to moderate our sugar consumption because they know when they add it to the food, we buy more - for all the reasons we've talked about.

FLATOW: You say it's a bad idea to skip meals if you want to lose weight - skipping breakfast, for example - bad idea.

LUSTIG: Right. Very bad idea for several reasons. The first reason: There's something called the thermic effect of food, TEF. You have to put energy in to get energy out, and the earlier in the day you put energy in to get energy out, the more you're going to burn. So if you eat breakfast, you'll start that process earlier, and you will actually burn energy faster during the day and feel better too; and you'll actually do better in school.

Number two: If you don't eat breakfast, and so many kids don't - they just fly out the door in the morning and don't eat breakfast - what happens is the hunger hormone, ghrelin, keeps rising as the day goes on. And so you will end up overeating at lunch and probably overeating at your 3:00 p.m. snack when you get home, and now - excuse me - overeating at dinner as well, and you will have consumed way more calories.

So you think you're actually saving calories by missing a meal. Not at all. So you're burning less, ultimately eating more, and driving weight gain and metabolic syndrome. Bad idea.

FLATOW: If you keep the temperature in your home or your apartment down lower and keep it a cool place, can you burn calories faster or more calories, lose weight, just by keeping the temperature down, because you have to keep your body temperature up?

LUSTIG: That's never been shown. Some people think that that's true, and it might even be true. But no one's actually ever done the study to say, OK, let's take everybody's, you know, ambient temperature down 10 degrees and see if it causes weight loss. My guess is it won't work. My guess is that you will burn energy a little faster because you're going to try to create some body heat, but ultimately that's going to translate into increased caloric intake to try to make up for it. I don't think it's going to work.

FLATOW: Talking with Robert Lustig, author of "Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease," on SCIENCE FRIDAY from NPR. I'm Ira Flatow, learning a lot today.

Can you be obese or overweight and still be healthy?

LUSTIG: Absolutely, for sure. Twenty percent of the obese population has completely normal metabolic parameters. They have normal metabolic machinery, and they will live a completely normal, healthy life and die at a normal age. They're just obese.

They are what we would call fat and fit, and it's easy to be fat and fit. You exercise. The problem is that all the doctors out there tell their patients if you'd only exercise, you'd lose weight, and of course it doesn't work. So what happens? They stop exercising because it didn't work. So as far as I'm concerned, that is the greatest disservice that the medical profession can do to a patient.

You know, understand what exercise is for. It's for burning that belly fat, for burning that visceral fat, for burning the fat that ultimately contributes to metabolic syndrome. So can you be fat and healthy? Absolutely. And can you be thin and sick? Absolutely.

As you said in the trailer leading up to the show, up to 40 percent of normal weight people have the same metabolic dysfunction as the obese. They're just not obese. And they're going to die of those diseases - cancer, dementia, Type 2 diabetes, lipid problems, stroke, et cetera - and they don't know it. That's one of the reasons why everyone needs to, you know, get with the program, and everyone really needs to read this book.

FLATOW: But if it's not going to make you lose weight, I mean you're saying do other things besides just exercising to bring that weight back down. Eat correctly, and that will lower your body weight.

LUSTIG: Well, what does eat correctly mean, you know? That's really what we're talking about here, is what does eat correctly mean? What I say in the book is that the two things that every successful diet share in common - the Atkins diet, the Ornish diet, the glycemic index diet, the South Beach diet, the paleo diet, you name the diet - there are two things that every single successful diet have in common: low sugar, high fiber.

Those are the two things that every successful diet share. So what's a low-sugar, high-fiber diet called? It's called real food. This is a processed food phenomenon. And when our processed food basically took over our diet in the '70s - and we did it for many reasons. We did it for convenience. We did it for cost. We did it because we now had two-parent working families. We did it because the fast food industry, you know, went, you know, through the roof.

We did it because we had the two-liter bottle. We did it for a whole bunch of reasons, but the bottom line is when we made that transition, that's when all of this occurred. This is a processed food phenomenon. We need to get back to what we used to do because there's no drug target, there's no way to fix this other than doing that. And like I said before, we don't have the money to be able to do otherwise.

FLATOW: So buy food with no labeling on it? That doesn't have any?

LUSTIG: Absolutely. If it doesn't' have a label, it means it's real food. As soon as you're buying - when you're reading labels, that means you're buying garbage, it's that simple. Because real food doesn't need a label.

FLATOW: All right, that's a good place to end it. Thank you very much, Robert Lustig, for joining us today.

LUSTIG: Thank you for having me, Ira.

FLATOW: You're welcome. Robert Lustig, author of "Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity and Disease."

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