I interviewed Gary Taubes by phone a few weeks ago, shortly after he gave a talk about the main ideas of his new book — "Good Calories, Bad Calories" — at UC Berkeley. The interview lasted about 2 hours.

SETH: I just spoke to someone who reduced the carbohydrate in his diet, for various reasons, including your book. He found that his performance on mental problems started improving again. It had stopped improving; it had been constant for a long time, and then it started getting better. So it may be that when you reduce the carbohydrate in your diet, your brain starts working better.

GARY TAUBES: Well, there is evidence that your brain works more efficiently on ketones, as does your heart. So if he reduced his carbohydrate consumption sufficiently, he probably increased the level of ketones in his blood. But I’m just speculating here.

SETH: The book seems to have had an unusual beginning. You’d been writing about salt, and you learned that a scientist you didn’t trust about salt was also talking about obesity?

GARY TAUBES: Well, I’ve spent over 20 years now writing about controversial science. In the mid-1980s, I lived at CERN for ten months, the big physics lab outside Geneva, watching physicists discover non-existent elementary particles. Then I wrote a somewhat infamous story about prions, the supposed causative agents of Mad Cow Disease. I wrote a book about cold fusion: I got obsessed with this question of how it happened, because it was so obviously wrong. After all that, I developed what I believe is a very good feel for who’s a good scientist, and who’s a bad scientist, just by talking to them. There are certain ways that good scientists describe their data, describe the caveats, and describe the conditions by which they may or may not be right. I had also, obviously, with cold fusion, interviewed some of the worst scientists in the world. I used to joke with my friends in the physics community that if you want to cleanse your discipline of the worst scientists in it, every three or four years, you should have someone publish a bogus paper claiming to make some remarkable new discovery — infinite free energy or ESP, or something suitably cosmic like that. Then you have it published in a legitimate journal ; it shows up on the front page of the New York Times, and within two months, every bad scientist in the field will be working on it. Then you just take the ones who publish papers claiming to replicate the effect, and you throw them out of the field. A way of cleaning out the bottom of the barrel.

SETH: I thought your NY Times article, “What if It’s All Been a Big Fat Lie,” sort of did that. The people who came out against it, they were the bad journalists. Just throw them out!

GARY TAUBES: Well, how I got onto that: I was doing this story for Science on salt and blood pressure, looking into the controversy about whether salt consumption plays any role at all in raising blood pressure and causing hypertension. One of the prime players in this salt/blood pressure controversy was obviously one of the worst scientists I’d ever met — one of the five worst…you can’t say, in that five, who is the very worst, but they’re all pretty bad. This is a group that includes guys like Stan Pons and Martin Fleischman who claimed to have discovered cold fusion. While I’m on the phone with this guy, interviewing him, he takes credit for getting Americans to eat less fat and fewer eggs. I literally finished the interview, called my editor at Science, and I said “You know, one of the worst scientists I’ve ever interviewed just took credit for getting Americans to eat less fat and fewer eggs, and I don’t know what the story is, but when I’m done with this salt story, I’m going to look into fat, cholesterol, and saturated fat.” I had a great relationship with Science. My editors had faith in me. If I said there was a story there, they’d give me the support I needed to pursue it. A year later, I ended up with that first story in Science, saying that there’s no evidence that reducing the total fat in the diet makes a damned bit of difference in our health. The evidence that saturated fat and monounsaturated fats are players is, at best, marginal. And that led to the N.Y. Times article.

SETH: What did that scientist say that made you rank him so low?

GARY TAUBES: There are all kinds of signs. He told me there was no controversy, when there was obviously a controversy. His side might have been right, but to deny there as a controversy was ludicrous. He talked about the legitimacy of throwing out negative data. You measure salt consumption one way; you don’t see any effect on blood pressure, and so you decide that’s obviously the wrong way to measure it. The implication of everything he told me was that he knew what the answer was before he did his experiments, and then he adjusted his experimental techniques and methodology until he got the answer that he wanted. And he believed this was legitimate science. There are other signs. I’m a stickler about the use of words like “evidence” and “proof”. So if someone tells you there’s no evidence for some controversial belief, you can be fairly confident that they’re a bad scientist. There’s always evidence, or there wouldn’t be a controversy. If somebody says that “we proved that this was true” or “we set out to prove that this was true” that’s another bad sign. The point here, as Popper noted, among others, is that you can never prove anything is true; you can only refute it. So researchers who talk about proving a hypothesis is true rather than testing it make me worried.

SETH: Yeah, I see what you’re saying. They overstate; they twist things around to make it come out the way they want. They are way too sure of what they…

GARY TAUBES: Yes, and the really good scientists are the ones, almost by definition, who are most skeptical of evidence that seems to support their beliefs. They’re most aware of how they could have been fooled, how they could have screwed up, or how they might have missed artifacts in their experiment that could have explained what they observed. They’re very careful about what they say. If you ask them to do play devil’s advocate, and tell you how they could have screwed up, then at the very least, they’ll say “Well, if I knew how I could have done it, I would have checked it before I made the claim”. So when I’m talking about discerning the difference between a good scientist and a bad scientist, I’m talking about how they speak about their research, the evidence itself, it’s presence or absence. My friends in journalism would often ask me this question: by what right do I think make decisions about who’s a good scientist and who’s not. I’d say “Well, when you’re an English major, you can be confident that Norman Mailer was a better writer than John Grisham, even though John Grisham makes 10 to 100 times more money”. It’s just a feel for what you do; I don’t know how else to describe it. I know a good scientist when I talk with one. I might be fooled, on occasion, but….

SETH: It’s not particularly well-correlated with how famous they are, or how many Nobel Prizes they’ve won.

GARY TAUBES: My first book was about a Nobel Prize winner who discovered non-existent elementary particles.

SETH Who was that?

GARY TAUBES: An Italian physicist named Carlo Rubia.