Dr. Roberts responds to my TCSDaily article

Dr. Seth Roberts recently published a book entitled The Shangri-La Diet. The plan it expounds consists of eating one tablespoon of either olive oil or fructose corn syrup an hour or so before meals. This will induce a reduction in appetite followed by weight loss. I wrote a less than favorable review for TCSDaily.

My reason for writing the review was that at the time, his book was number 2 at Amazon.com despite significant misgivings I had about it. I found his supporting evidence lacking in that it was based on "self-experimentation" ie. N equal to 1.

I have received a great deal of email about this piece, most of it negative. Dr. Roberts himself wrote a response as well. I would like to take this opportunity then to respond to him as well as his followers (most of whom don't think too much of me).

First off, my main objection to his book and to the statements he's been making to the media have nothing to do with whether his diet works. I thought I'd made this clear with the following:

"Any judgments I have about the plausibility of his theories are irrelevant to my argument. That I believe the Shangri-La diet will one day be a distant memory is no less speculative than Roberts' conclusions."

This is so because neither he nor I have offered the slightest bit of hard data in support of or opposition to any of his results.

Dr. Roberts has not been shy or circumspect about touting his credentials as an associate professor at University of California, Berkeley. However, despite his status as an academic, he has opted to bypass his own colleagues and the checks and balances of his own profession. Rather he chose to go straight to the lay press.

Why would he have done so? He has published scientific articles in refereed journals on psychology. He's performed studies. Presumably he is knowledgeable about accepted study design and methodology. Why wouldn't he have studied his diet the way researchers normally do when they want to establish the validity of a hypothesis (and I don't mean with a sample size of one) before publishing widely?

Obviously by mentioning his university affiliation, he intended to give the added weight to his conclusions that such a position would appear to justify.

Had he simply been a Beverly Hills secretary (as was Judy Mazel, author of the childish and scientifically unsound Beverly Hills Diet) I certainly would not have held him to the standards I discussed in my article. Of course, understanding the source, her readers would have been justified in doubting her credibility as a serious nutrition expert should they have chosen to.

So people, please, no more emails calling me an elitist for criticizing his work on the basis of its numerous methodological flaws. He opened the door to such criticism by circumventing the very peer review that is as much a part of his world as it is of mine. Dr. Roberts and I share space in much the same ivory tower.

As for specific points that he made:

• "Dr. Ford seems to be saying that my book is dangerous but on its face this is absurd."

I believe that a casual perusal of my piece will reveal that I made no such claim and in fact never addressed the issue of safety.

• "Dr. Ford has ignored facts that do not support his conclusions. If you search the Internet for people who are trying my weight-loss ideas, you will find many for whom it is working, often very well, and only a few for whom it has failed (harmlessly). Dr. Ford says nothing about this. "

I'm actually quite surprised that Dr. Roberts would have made such a statement after having read my piece. I criticized him for not subjecting his theories to methodological rigor. He counters this by raising anecdotal evidence despite the myriad of flaws introduced by such "evidence" (case ascertainment bias, selection and reporting biases, the placebo effect and others). Moreover he chastises me for ignoring such stories and saying "nothing about this".

• "...factual mistakes. (1) 'If Roberts were truly interested in investigating his approach, he should have subjected it to . . . peer review' – implying that I did not. In fact, my Behavioral and Brain Sciences article, which contained my weight-loss theory and support for my weight-loss methods, was peer-reviewed. So was a related article in Chance, which I told Dr. Ford about by email while he was writing his critique. Two is not zero. "

If he had read my article, he would have noted that I specifically addressed his Behavioral and Brain Sciences paper. I characterized it this way: "it was not about validating his hypothesis or conclusions. It was a speculative commentary on the use of self-experimentation as an idea generating tool."

That paper merely cites his weight reduction technique as one of many examples of a hypothesis generated by "self-experimentation". It did not in any way address the question of whether that particular hypothesis was externally validated. His Chance article essentially covers the same ground. Does he dispute this?

• "Finally, Dr. Ford is a medical school professor. For a long time, medical school researchers have contributed no useful ideas to our understanding of how the average person can lose weight."

It is perhaps best not to reply to such a bold and sweeping generalization.

Dr. Roberts closed his response with the following: "Time will tell which of us is correct." To which I say yes, but only if someone actually studies the diet.