Debate Revived: Low-Carb Or Low-Fat Diet?

Read Gary Taubes' New York Times piece "What Really Makes Us Fat."

Is a calorie just a calorie? Science writer Gary Taubes says no. In a study published last week in the Journal of the American Medical Association, diet researchers reported that patients on a low-carb diet kept weight off longer than those on a low-fat diet, re-introducing a long-standing debate.

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JOHN DONVAN, HOST:

So is a calorie just a calorie? Science writer Gary Taubes says no, it is not. In a study published last week in the Journal of the American Medical Association, Dr. David Ludwig of Boston's Children Hospital found that patients on a low-carb diet burned more calories a day and kept the weight off longer than those who are on a low-fat diet. In an op-ed called "What Really Makes Us Fat," in this past Sunday's New York Times, Gary Taubes argues that the study provides further evidence that following a low-fat, carbohydrate-rich diet may be a bad idea and contributing to America's obesity epidemic.

So dieticians and nutritionists out there, we want to know, what are you hearing from your clients? Please report to us from the field. And does this study change the advice that you give them? Our number is 800-989-8255. Or drop us an email, talk@npr.org. Again, dieticians and nutritionists, what are you hearing from your clients? So Gary Taubes is the author of "Why We Get Fat," and he joins us by phone from his home in Berkeley, California. Gary, thanks for joining us on TALK OF THE NATION.

GARY TAUBES: Thanks for having me.

DONVAN: So as I said, this study provides further evidence that low-fat, high-carbs is bad for you. What's been the preceding evidence, and where does this new study land on that spectrum?

TAUBES: Well, what's been interesting, there's been a debate for about a century about the sort of fundamental cause of why we get fat. You know, today the conventional wisdom is we just take in more calories than we expend. The official jargon is obesity is an energy balance disorder. And the counter hypothesis, the alternative hypothesis has always been that obesity is a - it's a hormonal defect, just like any other growth disorder. And the hormone that stimulates fat accumulation and fat cells is the hormone insulin, and we secrete insulin primarily in response to the carbohydrates in our diet.

You can think of the carbs in the diet as regulating our insulin levels. And so you've got these two competing hypotheses. One says it's just gluttony and sloth, and the other says that it's a hormonal problem, just like obese people are complaining for, you know, centuries, and that it's triggered by the carbs. And there's been a lot of evidence for this hormonal explanation, as I detail in my books, and along comes Dr. Ludwig's study, where - what they do is they take obese subjects, and they reduce them in weight down...

DONVAN: They just starve them for a few weeks or months?

TAUBES: Effectively they semi-starve them. They cut their calories and their carbohydrates by about 40 percent. So their weight comes down, and then now they're - they put them on a diet that's supposed to maintain their weight. So they're getting fed just as many calories as they're expending. And our energy-balance idea says if you do that, they're not going to gain weight or lose weight. And what Dr. Ludwig and his colleagues found was on the, you know, what the healthy diet - this diet we're told to eat by our - the USDA and the NIH, the low-fat, high-carb diet, their energy expenditure stays about the same.

So these people have to continue, in effect, to fight their hunger every day to maintain their weight. But when they switch to the very low-carbohydrate diet, suddenly their energy expenditure shoots up. And it's like now, even though they're eating just as many calories as they're expending, their expenditure has gone up, so they'd actually be losing weight.

DONVAN: But do...

TAUBES: And what...

DONVAN: Go ahead. Go ahead. I'm sorry. Finish your thought.

TAUBES: What I was - what I argue in this op-ed is that if you think of these weight-reduced people as pre-obese - in other words, they're just like the rest of us who are going to get fatter - we just know these people are going to do it quicker - then what this study tells you - it's premature, it's short term - but it tells you that the more carbs in the diet, the harder it is to maintain your weight.

DONVAN: So Gary, when you say the study tells us this, should we consider ourselves, at this point, told? Is this definitive and clear-cut, or is it murkier than that?

TAUBES: Oh, it's - you know, what I'm tell you is, as I say in the op-ed, it's very controversial. And what I've been arguing is it should not be controversial. You know, up until the 1960s, the conventional wisdom was that carbohydrate-rich foods were fattening: pasta, bread, potatoes, sweets, beer, sodas. You know, that one line I quote in the op-ed is from a British Journal Nutrition article in 1963, written by one of the two leading British dietitians. The first sentence was: Every woman knows that carbohydrates are fattening.

And then what we did is we got this idea in our heads that dietary fat causes heart disease, and we made - the fattening carbohydrate got transformed into this idea that carbohydrate is heart-healthy diet food.

DONVAN: Which was a gigantic change in the cultural attitude towards food, was it not? It was like the change in getting us to wear seatbelts and to stop smoking. People really did make that change.

TAUBES: People really did make that change. And you can actually see it in the statistics in the USDA food availability statistics. Carbohydrate consumption goes up. Sugars consumption goes up, and fat consumption goes down, consistent with what we were being told beginning in 1977 by the government. And this coincides with an obesity epidemic and a diabetes epidemic.

And, again, the argument that I've been making is, you know, the conventional wisdom remains to this day, it's all about calories. It's all about eating too much, exercising too little. And we've been given that conventional wisdom as the nation has gone fatter and fatter and fatter. And what the authorities do is they blame us, the public, for not following their advice. The counter-argument is the advice is wrong, that what they've been telling to do has made the problem worse, not better.

DONVAN: Let's - we've asked listeners who are actually working in the field and advising people to call in and tell us, you know, give us a report from your office, from your clinic: What are you seeing, and also what are you advising your clients to do? So let's go to Oakland, California. And, hi, you're on TALK OF THE NATION. Oh, I'm sorry. I'm afraid, we lost you. I want to go to Blair, then, in Pembroke Pines, Florida. Hi, Blair. You're on TALK OF THE NATION.

BLAIR: Hey. How are you?

DONVAN: We're good, thanks.

BLAIR: Listen, I just - my son is a real health nut. And about three months ago, after spending a year-and-a-half working on three times a week and gaining two pounds, up to 250 when I should weigh about 210, he said, you ought to read this book, dad.

DONVAN: By whom?

BLAIR: I did - I read it. And three months later, and even exercising less, I now weigh 215. I'm almost at the same weight as I played at basketball in college. And I'm telling you, your science is exactly on target.

DONVAN: Which book are you talking about, Blair?

BLAIR: "Why We Get Fat: And What to Do About It."

DONVAN: All right. Gary, you didn't plant that, did you?

(LAUGHTER)

TAUBES: No, I didn't. Thank you. I was wondering (unintelligible) California. I was hoping we'd hear from Oakland, too, but thank you.

BLAIR: I have a website called The Transformation, and I wrote an article about it, to all the people to go get your book, because it's absolutely on target. And three things happened to me lately. One, I quit getting hungry after three days. Two, I quit being tired in the afternoon. And three, I lost 35 pounds...

DONVAN: All right.

BLAIR: ...in three months.

DONVAN: Blair, thanks very much for your call. You know, one thing that I want to clarify with you, Gary. When you talk about low-carb diets, I mean, an apple is essentially carbohydrate as much as a bun. Are the recommendations - the implication - the implied recommendations from the things that you're talking about in your work, that we don't eat as much fruit and vegetables.

TAUBES: Well, this is what complicates the matter a lot, and why a lot of dietitians and nutritionists have trouble accepting the arguments. You know, we have these blanket recommendations for the nation that fruits and vegetables are good for us. And I'm going to hear, separate out, you know, potatoes or starchy vegetables versus green, leafy vegetables like broccoli, kale, spinach. The argument I've been making again is that the - and this is not, you know, I make this argument in my books. I'm not taking credit for it. I'm just channeling a lot of other intelligent researchers and commentators going back a century.

But, you know, the idea is if you're overweight or obese, you're particularly sensitive to the carbohydrates in the diet. So just like, you know, of - 10 percent of all smokers will get lung cancer, but we know that for those smokers who do, 80 to 90 percent, cigarettes are the reason. And I'm making this argument that, you know, for those of us who get overweight and obese, the carbohydrates in the diet are what's causing it. So if you're a lean and you want to remain lean, then, you know, eating fruits and starchy vegetables are fine as long as your body can tolerate it. But if we're talking about somebody who's 100 pounds overweight or is a type 2 diabetic, then arguably, even the carbohydrates in fruit are going to be problematic...

DONVAN: All right.

TAUBES: ...and that you can't give the same prescription for a lean individual as you can an - you know, an overweight individual, as an obese individual. The greater the problem, the greater the metabolic disturbance - a phrase we use a lot - the more extreme the intervention. So for someone - for a third of the country that's obese, fruit is going to be problematic. That's a question(ph). And maybe, if they get rid of it and keep their diet to green - only the carbohydrates and green, leafy vegetables, they'll be able to reverse the problem, lose the weight.

Even in some cases, clinical trials have demonstrated that type 2 diabetes can be reversed by severe carbohydrate restriction, which - kind of(ph) a low-carbohydrate, high-fat diet, and then find out a few years later that their body has normalized and now they can tolerate more carbohydrates in diet, including that apple.

DONVAN: All right. Let me bring in Lawrence from Houston, Texas. Hi, Lawrence. You're TALK OF THE NATION.

LAWRENCE: Yes, hello.

DONVAN: Hi. We hear you. Lawrence, you're on the air.

LAWRENCE: Hello?

DONVAN: You're on the air.

LAWRENCE: OK, yeah. First of all, (technical difficulties) a fellow USC Berkeley grad. I graduated in physiology and engineering, so I know quite a few of the same folks you do. I'd like to get your comments on the China Study, because I've been getting more and more involved in the results of the China Study, which, as you probably know, is the largest epidemiological study ever made. It's OK to look at single components of nutrition like carbohydrates and proteins and fats. And we all know that it takes more energy to burn a, you know, a gram of protein than it does a gram of fat, for instance. It's nine grams versus - nine calories versus four calories.

But when you take the relationship between disease and all kinds of diseases, different kinds of cancer - you know, hepatitis B and heart disease - and you look at the relationship and large groups of populations between what their diet is and the occurrence of the disease, there's an astonishing relationship between animal protein and disease occurrence. I...

DONVAN: Lawrence, I need to step in just to give Gary a chance to begin to answer, because we're almost out of time. So thank you for your call. And, Gary, I have to give you about 40 seconds to answer.

TAUBES: Forty seconds, OK. The quick question is the China Study is - well, it's a collaboration between Cornell, Oxford University and Chinese universities that looked at diet versus disease (unintelligible) counties in China. It is actually not true. This is one of the amazing - the China Study has become sort of the bible of the vegan diet movement. And it's actually not true. If you look at the raw data in the China Study, there is no relationship between animal protein and cancer - animal protein consumption and cancer mortality in that study. Anything more than that, I'd be happy to talk about the China Study for minutes to hours. That's all I can say.

All right. I want to thank - I'm afraid that we're out of time. But Gary Taubes, I want to thank you for joining us. You are at home in Berkeley, California, the author of "Why We Get Fat," and "Good Calories, Bad Calories." Gary Taubes, thanks very much for joining us.

OK. Thank you again.

DONVAN: And this is TALK OF THE NATION, from NPR News. I'm John Donvan, in Washington.

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