Friday, March 30, 2012

That damn chocolate "study."

Earlier this week I was in the car listening to NPR (yeah, I'm one of those 'informed people' so sue me) and they start talking about a press release from the UCSD. Jumping to all kinds of weird and wild conclusions, I'm sorry to say: most of which can probably be assumed to be wrong.

First off this was a "Food frequency questionnaire" which is predictably unreliable.
People under report, forget, or outright lie. People answer what they think about themselves (I'm a good person I only eat chocolate very seldom), or what they think they "should answer." So this had me rolling my eyes from the jump. (aside Robb Wolf has an excellent takedown of these silly things a while back when a similarly silly conclusion came from one.)
Similarly people who are heavier in our society tend to have a screwed up sense of self worth tied up with food. They don't want to admit that they eat "bad food" frequently even on an anonymous questionnaire. People who are lighter tend to have a less screwed up relationship with their food, so were probably more honest in their reporting.

Even the title of the piece set me off: "Does A Chocolate Habit Help Keep You Lean?" I don't know.. NPR doesn't know.. the people who did the study don't know. Because there was no measurement of the 'leanness' of the subjects. They were asked for their BMI, which.. is complete bunk.
The actual press release was more honest. I was titled "Regular chocolate eaters are thinner" and BMI is a measurement of 'thinness' sort of.. I guess.

Post hoc ergo propter hoc. "After this therefore, because of this."
I am listening to this piece of.. journalism.. and thinking; Ok, give them benefit of the doubt. Assuming all of the data is valid, why would people who are thinner eat more chocolate? or more correctly why are people who weigh more eating less?
They're on a diet!
That's right people who weigh more in our society tend to abstain from foods like chocolate. Perhaps that's why the people who are heavier eat less of it? For some reason to the folks at UCSD it was a gigantic leap of logic that heavier people are on a diet and it makes far more sense that 'chocolate has magical properties that keep people thin.'

A more detailed break down of this HERE.



Code name: 1% said...

Ah ha ha ha ha. I eat chocolate pretty much every day, but I'd be willing to bet that even then I eat less chocolate or total sweets than most people who would claim to eat chocolate just once a week.

J. B. said...

Yeah Doc, It's completely baffling that these questionnaires get published as science. It's kind of horrible.