Science diet

Were you surprised by the lack of science behind the low-fat diet recommendations? Is there a lack of evidence for the other underpinnings of our medical do’s and don’ts?

Like everyone else, I believed the official line on dietary fats implicitly until I started doing this research in the 1990s. I ate skinless chicken breasts and ate my pasta with fresh salsa—I lived in Los Angeles through a lot of that time—to keep the proportion of fat in my diet as low as possible. So, yes, when I actually got around to looking at the evidence and reading the papers, I was appalled by how little substantial science there was. Now I tend to be skeptical of everything. I don’t know if it’s all as bad as nutrition. I certainly hope not, but I do believe that this tendency to take shortcuts with the scientific method, which I discuss at length in the book, is probably pretty common in medicine.

The Reno-Tahoe area is a haven for outdoor recreationists. There was very little focus in the book on exercise. Why?

My primary interest was examining this issue of what causes the chronic diseases that are particularly common in populations that eat Western diets—heart disease, diabetes, cancer, obesity, etc. The only way exercise entered into it was this question of whether we get fat because we’re sedentary or whether we’re sedentary because we’re somehow hormonally driven to get fat. The evidence for sedentary behavior as a cause of weight gain, or exercise as a way to reverse it, is very poor, and that’s the only point that was really relevant. I am personally interested in whether physical activity makes us healthier, or whether healthy people tend to be physically active. I believe the latter is surely true; the former I have my doubts about.

How long did it take you to write the book, and what was the process that you went through?

The research for the book grew out of a series of lengthy articles I wrote first for the journal Science beginning around 1994. Once I got a book contract after writing a very controversial cover story for the New York Times Magazine ("What If It’s All Been a Big Fat Lie?” which was published in July 2002), I worked on the book for five years straight, with maybe a handful of days off in that entire time. I describe my research process at the end of the prologue, so you might want to check that out for the details. But basically, I just ask what seem to me to be reasonable questions—why, for instance, doesn’t eating less make people reliably thinner if eating more is supposed to make them fatter—and then I keep reading the literature, following the references backward and forward in time, interviewing anyone who ever did any relevant research, until I get an answer that makes sense.

One reason the book took so long is that I would often run into questions I never anticipated and these would eat up weeks of research. Why, for instance, do medical researchers now insist that sugar could not be the cause of diabetes, when this was an active area of debate 80 years ago? For that single question, I ended up buying every edition of Joslin’s Diabetes, the classic textbook in the field, going back to 1917, when it was first published. Joslin, the author and the most famous diabetes specialist in the United States, argued that sugar could not be the cause of diabetes, and I wanted to find out if he ever presented compelling evidence to back up his point. Six weeks gone right there. And that was just one of maybe a few dozen such issues that had to be addressed.

What has been the reaction so far to your book from the medical community? Especially those who study nutrition, diabetes, heart disease? The public?

Regrettably, not what I would have hoped. My 2002 New York Times Magazine article caused such a huge controversy that I imagined the book would do so, as well. Instead I’ve mostly been preaching to the choir. Those people who believe that carbohydrate-restricted diets are both healthy and the best way to maintain their weights or lose weight embraced the book. The mainstream medical community for the most part seems to be thoroughly uninterested in being lured into a debate on these issues. (Although I have been told that one of the premier medical journals, Nature Medicine, is publishing a review in the February issue. So a few more days and we’ll see.) I just got an email from a well-known nutritionist apologizing for not yet getting around to reading the book. It is a big book and requires some effort in time and attention, so I guess I have to be patient. In the meanwhile, I have been lecturing at medical schools, courtesy of clinicians who do find my writing at least thought-provoking, if nothing else. And I’ll be lecturing at a couple of national conferences in April, so I’ll have a chance to challenge the preconceptions of the specialists directly and maybe prompt them to read the book, if they haven’t yet.

Given all that you have learned, what do you eat?

I tried the Atkins diet as an experiment when I was writing my first article for Science on dietary fat. All I did was give up starches and sweets, fruits and fruit juices, anything made from flour or sugar, and I ate meat and cheese and eggs, etc., to my heart’s content. I lost weight effortlessly, which was one of the more surreal experiences of my life. So I never really went back to the carbohydrates. I like being (relatively) slender without having to exercise. I still do it. I still go to the gym regularly, do some yoga, fantasize about living in a place like Reno where I could hike and ski regularly, but I never went back to the carbohydrates. So I have eggs and bacon for breakfast, and some kind of meat or fish or fowl and a green vegetable for lunch and dinner. Snacks are usually yogurt, cheese or nuts. That’s pretty much it.