Author: Seth Roberts

Science in Action: Omega-3 (more memory results)

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Several weeks ago I compared flaxseed oil (high in omega-3) and olive oil (low in omega-3). I’ve posted results from a balance task and a memory-scanning task. I also measured what is called digit span — the number of digits you can remember perfectly after one presentation. It is a widely-used measure of short-term memory. In my test, the digits were shown one by one for 1 second each on my computer screen. A few seconds after the last one, I had to write them down in order. If I was 100% correct the next trial had one more digit than the last. If any of my answers were wrong, the next trial had one fewer digits than the last. The test continued until there had been six “reversals” — right answers after one or more wrong answers, or wrong answers after one or more right answers. The measure of performance is the mean of the six reversal points. It estimates the list length at which I have a 50% chance of being correct.

Here are the results:

flaxseed oil vs. olive oil

Performance was better with flaxseed than olive oil (t = 2.5, one-tailed p = 0.01). The difference — the omega-3 effect, you might say — was quite a bit weaker than what I saw with balance and memory scanning. My guess is that the relative insensitivity of this task comes from two features: 1. Binary measures. Each trial is measured right or wrong; whereas with the memory-scanning and balance task, each trial yielded a duration (many-valued). 2. Slow. Each trial takes about 30 seconds; it takes about 10 minutes to get six reversals.

Guide to my omega-3 posts.

SLD in Paperback: What’s New

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The paperback edition of The Shangri-La Diet was published last week. The feedback I’d gotten, mainly from the forums, suggested many changes, so I was glad to be able to revise it. The main revisions are:

1. A foreword about events since hardback publication.

2. More emphasis on flavorless oil, less emphasis on unflavored sugar water.

3. New case studies (to match the emphasis on oil).

4. Data from the Tracking Data forum about how fast people lose.

5. New sidebars about omega-3, combining SLD with other diets, and how to drink oil.

6. Nose-clipping as an important new way of doing the diet.

My thanks to all SLD forum contributors and others who provided feedback.

What If College Were Taught by Basketball Players?

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1. “I don’t teach passing, I teach teamwork,” says a Professor of Ball Handling at an elite university.

2. The more prestigious the school, the taller its students and professors.

3. The Bell Curve is about the advantages of being tall. Taller people have better life outcomes, the authors discover via analysis of a large data set. Curiously, the authors — both tall — conclude that tall people should be favored even more.

4. The better students say that at college they learned how to learn. They mean they learned how to learn to play a sport.

5. At “research” universities the professors spend more time playing basketball than teaching.

6. A Princeton, New Jersey company develops and sells a fast standardized way to measure basketball ability.

7. Sports Illustrated publishes an essay titled “What Every Educated Person Should Know.”

8. By graduation, students know very well how good at basketball they are but know almost nothing about their ability in other areas.

The excellent humorist Henry Alford wrote “What If” articles for Spy magazine and, more recently, for Vanity Fair, such as “What If Paris Hilton Were President of the United States?”

A Stanford Nutrition Professor’s Explanation of SLD

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A Palo Alto resident found SLD so effective (lost 10 pounds in 1.5 months) that he told others about it. “Everyone I speak to about the diet laughs at me or just shakes their head,” he wrote. (Which is good.) A tenant of his, a Stanford medical student, asked his nutrition professor how such a crazy diet could possibly work. The professor, Dr. Clyde Wilson, replied:

Fats and sugars reduce hunger when consumed in moderate amounts. Fructose stimulates less of an insulin response than glucose, putting you at less risk of subsequent hunger. Flavored foods result in a greater caloric consumption. Unflavored fructose and olive oil would therefore reduce hunger during a subsequent meal. Any small healthy snack will provide the same result. A small healthy snack would be, for example, a whole grain cracker with some peanut butter and half an apple.

The interesting thing about SLD is not that the oil or sugar water reduces hunger — most food does that — but that it causes easy weight loss. This is what needs explaining. Why does X calories of sugar water cause you to reduce future consumption by more than X calories? This paragraph doesn’t explain this.

Since fructose, sucrose, and unflavored oils all have the same effect, it cannot be due to a special property of fructose.

As for the prediction that a small healthy snack will have the same effect, that has not been my experience. I’m pretty sure that weight loss would not be such a big problem if one could lose substantial weight (such as 10 pounds in 1.5 months) by eating as many small healthy snacks as you want.

Guest-Blogger Timothy Beneke on Self-Control (part 2 of 2)

Seth Roberts7 Comments

I continue to struggle — not terribly — but still struggle with compulsive eating. The forces in me that caused me to gain 100 pounds between 1982 and 1996 still exist in my personality. When I am stressed, I want to eat. I probably have gone about 35% tasteless in the last 2 years. I would like to get skinnier, to push my blood pressure down as much as within reason, and get rid of the fat on my belly; my waist is around 39 inches — I am 6 feet and of moderately large athletic build. I have the tendency, when I want to go mostly tasteless for a day to impulsively give in and overeat. I was misconceiving this as an issue of will.

What I’ve discovered lately is that I was confusing “willpower” with technique. Low blood sugar can manifest as depressed mood, lightheadedness, vague disquiet, and more obviously food fantasies. It can be subtle. If I attend carefully to my mood when I am trying to go tasteless, attend to my hunger levels and always have the mush and water available, I can manage my blood sugar levels and not have sudden attacks and fantasies of food. If I anticipate times when I may be experience such attacks I can preempt them. The conjunction of being around available food and having blood sugar drops leads me to eat compulsively. So now, I keep the mush next to my computer when I work, have it with me wherever I go and if I notice a sudden sign of blood sugar drop that may lead to compulsive eating, I consume a small bit of mush.

I would like to take this experiment as far as it will go but have not yet had the motivation to do the requisite work. I would like to see how thin I can become — within reason — using the method. It’s a matter of going predominantly tasteless for 3 months as I did in the summer of 2005, when I went from 210 to 177. I’m at 188 now. Time will tell whether I can pull it off…

Part 1.

Where Do Useful Discoveries Come From?

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From Andrew Gelman’s blog:

On page xxi [of Nassim Taleb’s new book The Black Swan], Taleb says how almost no great discovery came from design and planning.

I said something similar to a graduate student last week: Really useful discoveries are almost never the result of trying to do something useful; they are almost always due to accidents. Penicillin, for example. If you notice something by accident, it must be a big effect otherwise you wouldn’t have noticed it. That’s a great place to start: A big effect you didn’t know about.

I’ll have to see what else The Black Swan says about this. It makes self-experimentation look really good: (a) It’s much easier to to do a self-experiment than to do a conventional experiment so there is more chance of accidents; and (b) because we pay close attention to ourselves, it’s much easier to notice the unexpected with self-experimentation than with conventional research. Every useful finding in my long self-experimentation paper — breakfast, morning faces, standing, morning light, sugar water — came from an accidental discovery. In four of the five cases, the accident happened during a self-experiment; I varied something to see if X would change and noticed that Y changed. The exception was sugar water, whose appetite-suppressing effects I noticed while traveling. Hmm. Maybe travel is a type of self-experimentation. Or self-experimentation a type of travel. Certainly they are closely related.

Injury-Causing Falls: The New Scurvy?

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In an article about aging in this week’s New Yorker, Atul Gawande writes:

The single most serious threat she faced was not the lung nodule or the back pain. It was falling. Each year, about three hundred and fifty thousand Americans fall and break a hip. Of those, forty per cent end up in a nursing home, and twenty per cent are never able to walk again. The three primary risk factors for falling are poor balance, taking more than four prescription medications, and muscle weakness. Elderly people without these risk factors have a twelve-per-cent chance of falling in a year. Those with all three risk factors have almost a hundred-per-cent chance.

Could the cause of so much falling be too little omega-3? My omega-3 research suggests that more omega-3 quickly improves balance and that current levels in most places are far below optimal.

Blogger Alert: Paperback SLD Available

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If you have a blog, would like a copy of the paperback edition of The Shangri-La Diet — which is substantially better than the hardback, I like to think — and are willing to review the book on your blog, please contact Katherine Wasilewski (X.Y@ us.penguingroup.com where X = katherine and Y = wasilewski). She has 50 copies available. Please put “SLD review copy” in your subject line.

Addendum: The earlier version of this notice failed to say that these copies are for bloggers who will review it. I will soon post how the paperback is different from the hardback. The main difference is it incorporates lessons learned from forum feedback.