Meet Our Guest Blogger

In yesterday’s New York Times Magazine, we wrote about a Berkeley psychology professor, Seth Roberts, whose intriguing history of self-experimentation has led to, among other things, a very interesting new diet. Click here to read the article and here for some extras, including Seth’s academic papers, photos, etc. Because there has been great interest in the article, we asked Seth if he would like to do some guest-blogging and he has accepted. Below are his first postings. Please welcome him and feel free to send comments and questions.

Pleased To Meet You
Sun., Sept. 11

At a dinner a few weeks ago I told the woman sitting next to me, whom I didn’t know very well, that I was writing a book about how to lose weight. “Have you heard of the book Freakonomics?” she replied. Huh? What did a weight-loss book have to do with Freakonomics? She said that just as I, a psychology professor, would no doubt use the tools of psychology to help people lose weight, Freakonomics was about using the tools of economics to answer other questions of everyday interest. Yeah, you’re right, I said. She was more right than she knew.

I was thrilled when Dubner invited me to guest-blog here because I enjoy reading this blog. I felt like a small boy who has been given a tour of a submarine and then the tour guide says: Would you like to drive it for a while?

It’s Sunday morning and the article about my work has been out for about a day, if only on the East Coast. I’ve gotten about 12 emails (oops, make that 14, I got 2 while writing this) and 2 phone calls. The emails begin: “I’m sure you’re going to be inundated…” This reminds me of a letter I wrote to Spy, with what I thought was a correction: “Let me be the twenty-third person to tell you that…” my letter began. “Actually you’re the first,” Spy replied, because my correction was wrong.

Dubner has suggested I blog about what it’s like to be written about as well as what I found wrong with their article. In future posts, I’ll do that. I’ll also write about Andrew Gelman’s interesting comment that “self-experimentation is the opposite of the NIH approach to medical research,” the response to their article (the supposed “inundation”), and how lucky I felt. I’ll also try to answer the questions that come up. And I will do it without praising Levitt and/or Dubner — Dubner has specifically said I shouldn’t do that!

Mon., Sept. 12: The Big Day
Yesterday was the big day, huh? (It is now Monday morning.) Well, I did get more e-mails from strangers (perhaps 30) than any other day in my life. And it felt wonderful to see such interest in my work, especially my work — if you can call it that — on acne. (I will say more about acne in a later post.) I didn’t hear from any “long-lost” friends. 🙁 ! I did speak to a potential book agent on the phone. “Now you have a picnic to go to,” she finally said.

She believed that everyone there would know about the Times piece. “Actually, I don’t think any of them will,” I said. I was right. At least, no one mentioned it. There was one close call. “This is our friend Seth,” the host said, introducing me to someone else. “He is the person who…” He paused. Uh-oh, here it comes, I thought. He continued: “Who met us in Beijing when we went to China.”

The most interesting e-mail I got was from a journalist who is writing a book about the harmful effects of sugar, including (or perhaps especially) fructose. She sounded very alarmed; she commented on Dubner’s Friday posting about the Times article so you can see for yourself what she thinks. I rarely consume fructose these days — not for health reasons but because sucrose is a lot more convenient and works just as well. I have Steve Levitt’s sister Linda to thank for my conversion here. (Doesn’t count as praising, Dubner!) The journalist wanted to speak to me. I replied, “I’m always happy to talk with people who disagree with me. As you say, maybe I’ll learn something.” I am curious to see what happens.

So much for the big day. It was exciting, don’t get me wrong. I think because of the excitement I am losing weight.



i dont understand all the talk of glucose, frctose, glycemic indexes. Should have focussed on those Biology Classes !!


See now why science education needs to be vastly improved in this country?


If the discussion of sugars, glycemic index, etc. is confusing you, an easy introduction would be reading the South Beach diet book. It approaches glycemic index as the primary factor in how your body absorbs categories; once you are comfortable with that explanation of sugar, insulin, and processed foods, it might be easier to make sense of a theory that combines glycemic index with taste.

Or the quick version: different sugars absorb into your body at different speeds. How much of a sugar rush your body gets depends on how much and what kind of sugar a food has. Beer, for example, has a lot of maltose, so your body tries to absorb it immediately and convert it into the classic beer belly. This would be a good example of a calorie source with strong flavor, quick-absorbing calories, uniformity, and frequent repetition (soda is another). Foods with less sugar cause less of a spike, as do foods with slower absorbing sugar. For example, an apple is harder to absorb than apple juice, peppers are better than potatoes, and so on. (You can easily find glycemic index charts online - low means less sugar spike.) These foods, under Roberts's theory, would be less likely to cause the connection between taste and calories, so your body would have a lower set point for weight. South Beach attributes this primarily to an insulin reaction, rather than a Pavlovian response based on taste; the two approaches would have similar implications for many things, but some different recommendations, and it should be testable which affects weight more in the long run, with a larger n.



If the diet drug you're testing is sugar, what do you use for a placebo in the control group ;-)




Seth, would you please send me the exact measurements for fructose/water in layman's terms?
Please send to I find your studies extremely interesting. Thank you.


Seth:I too would like the simple syrup recipe, and also I am not clear on why you added oil and what its effect is. Great job finding a usable diet plan. Can't wait to try it.
As always the Freakonomics column lives up to its potential with interesting quirky problems and their solutions.


Dr. Roberts: The NYT article briefly mentioned your research on acne, but I can't find any further descriptions; can you direct me?


Hi, folks,

I've created another blog at , where we can continue discussion and posting of our results trying the diet. Please post there so we can continue to get support and feedback from each other (those of us actually trying the diet), unless someone has a better spot for us to blog.



Hi Seth.
Do you have a simple breakdown of your diet so I can try it?


When I read about your n=self study designs, I thought of orthopedic surgeon Scott Dye, MD, who allowed his research partner to palpate the various internal anatomical features of his knee, without anesthesia, in order to collect data on the knee's "consious neurosensory characteristics" (what it feels like). The researchers found that certain structures were indeed extremely sensitive, and while the experimental design called for collecting data from both knees, they decided during the course of the experiment that data from one knee would be enough. Dr. Dye et al. published details of the experiment in the American Journal of Sports Medicine: The results of the study have been of value to clinicians seeking to understand and treat problems such as anterior knee pain (runner's knee).


Can you use flax oil instead of olive oil between meals?


Have you tried stevia (an arguably healthy, sweet herb) water instead of sugar water?


I have commented on the commenter here:

Is honey a possability to replace the sugar? Or would something like straight carrot juice or celery juice work? Carrot juice has a very low-glycemic index.

Flax oil would be much better than canola--unless you use un-refined. Is the flavor an issue--as in it's a trigger to hunger? So one wouldn't want to use a Tuscan Extra Virgin olive oil? Or is it just a matter of personal preference--if I'm going to have 3 or 4 Tablespoons of oil a day I don't want to know it?


Oh man, I am rooting for your diet just because it would be hilarious if it worked. Imagine if all the billions spent crap diets and fads washed away with a few cents of sugar mixed in water!

Are you shorting Weight Watchers (WTW)?


A number of people are confused as to the exact dose and concentration of fructose/sucrose or vegetable oil that you ingest in order to comply with your diet. Can you elucidate more on this? Another question brought up is whether taking fish oil in gelatin capsules in between meals will work just as well since it doesn't have any taste. Once again, thanks for being our guest blogger!



Congrats on your new found fame ;)

I've read your papers and can't find any mention of the self-experimentation you've done with oil instead of sugar water. Can you provide details of the number of days where you have used oil? Is the number of kcal with oil the same as with sugar water?

Thanks in advance.


SR: I felt like a small boy

Yup, you're in the right place!

SH: And I will do it without praising Levitt and/or Dubner -- Dubner has specifically said I shouldn't do that!

Aw, come on, a lot of us would love to see a menage a trois!


One disadvantage of using fish oil is that it will increase your mercury levels.


I tried the diet for about a month after the paper was featured on MarginalRevolution and it didn't really work for me. I used 15 g of fructose (5 "Estee" packets) in 1 liter of water. The oil thing is new, though.