Friday, August 3, 2012

Shangri-La Diet II: Another Go with More Theories

I'm going to carry on with the crazed oil-eating for another month and see what happens.

Currently my belt likes to be on its third notch all day.

My plan is to drink two tablespoons of (to me, utterly tasteless) Sainsbury's Mild Olive Oil as soon as I get up, then not to allow myself to touch anything I can taste (including toothpaste) for the next hour (best accomplished by going back to bed for an extra hour). After that I'm trying to deliberately forget that I'm trying to lose weight and eat what I like, when I like.

I called the three models that I had Willpower, Helplessness, and Shangri-La, and they make the following predictions:

Willpower: Eating 300kcals worth of oil every day on top of eating normally should result in weight gain.

Helplessness: Slight appetite loss should compensate exactly for extra calories, no change.

Shangri-La: Severe appetite loss should result in further weight loss.

I also want to introduce a new theory, which I shall call "Ruth". Ruth on the basis of many experiences with diets thinks that any new diet will work for a while, but after a bit you'll put all the weight back on.

That strikes me not compatible with the willpower model. If it's just to do with how much you eat over how much you exercise, then once you've lost the weight there's no reason that it should go back on.

But it is compatible with helplessness. By force of conscious will you can make yourself eat less, but your weight will drop below your 'set point', and the pressure from your subconscious to eat will grow greater, until you break and start eating enough to get your weight back up to where it's supposed to be.

And it's also compatible with the theory behind Shangri-La. As far as I understand it, Seth Roberts also predicts weight loss from any strange new diet. Your set point drops in response to not tasting familiar tastes as often, but after a while you adjust to associate the new tastes with calories, and then your set point returns to normal. In fact it was noticing this effect in both rats and on himself that prompted him to start trying to break that link. As I remember he predicts that the time lag for learning the new flavours is around a week. I'm pretty sure that's not happening to me. If it was, I'd be looking forward to my daily olive oil dose by now. As it is, it still tastes entirely neutral. I neither like nor dislike it.

Ruth doesn't say how long the cycle should take. So I'm going to split her theory into three: Ruth I, which says that you should lose weight on a new diet for one month, and then the next month should return to normal. Ruth II gives you two months of weight loss and two months of regain, and Ruth III is the three month version.

I think Ruth knows what she's talking about: Apparently the only robust result in nutrition science is that any attempt at weight loss eventually fails and the weight goes back on.

So I'm going to mess with my prior (currently H55:W36:S9). Ruth's theories seem like versions of my Helplessness scheme, so I'm going to take 15 points from that, and split it three ways between RI, RII, and RIII.

So, my prior beliefs are now frigged to be (H40:W36:S9:RI5:RII5:RIII5).

I must say that this really doesn't feel like what I actually believe. After last month's dramatic success I have a strong hunch that Seth Roberts is right. But I'm trying to use Bayes' Theorem to keep me honest.

So my official rational beliefs are now that last month's weight loss was a fluke, and that either the traditional Willpower (eat less, exercise more to lose weight), or my own Paleo/Helplessness theory (as long as you avoid fast carbs it doesn't matter what you eat, your weight will stay at its set point, bad luck if your set point is too high or too low) are true.

But I'm now allowing a combined quarter chance to a combination of Seth Robert's Shangri La Diet theory and Ruth's rebound theories.

And because my actual emotional belief has shifted strongly towards 'Roberts is right', I'll need to watch myself very carefully looking for ways in which I'm screwing up my observations or my priors to fool myself.

Never trust a brain! I'll repeat "If it's true I want to believe it's true. If it's false I want to believe it's false." several times every morning in the hope that it will magically make the untrusted hardware I'm running on more sciency!


  1. > Currently my belt likes to be on its third notch all day.

    Real girls use scales :-)

  2. It's not what I'm interested in. I'd consider weight loss accompanied by a gain in spare tyre to be a disaster. Weedy and fat. Ugh!

    On the other hand, loss of girth and increased weight would probably be a good thing, as long as the extra weight were muscle mass.

    From a data collection point of view I should probably be using scales as well as the weight measurement, but I don't have any.