Tuesday, March 27, 2012

Tortured by Chocolate: When Weak Studies Happen to Sacred Goods


Chocolate study author Beatrice Golomb, PhD, MD doing research?
Why oh why didn't I stick it out in academia for studies like this?
Credit: Image, University of California, San Diego Health Sciences.
Chocolate makes people skinny? 

Forget the kids once again. This isn't really about them, it's about the parents, me actually and my right to relish chocolate free from tainted claims.  So let's focus once more on food and disappointing health reporting.  This time my beef is with chocolate, momma's little helper, the one Mick didn't mention though I do agree with him, kids are different today.  Yes, I'm talking about that little survey showing people who eat chocolate more days of the week also weigh less, the one that's caused some senseless conclusions. 

Like the short blurb on NPR's Morning Edition that awoke me this am.  I know it was pre-caffeine but I swear a young woman said, without a whiff of skepticism, chocolate promoted weight loss. Can't find it without listening to the whole show again (anyone hear it?). Soon thereafter this headline greeted me on Twitter:

Chocolate Helps You in the Unending Quest to be Skinny

I can already hear my brother...if it "helps" is it really an unending quest...define unending...

So I had to read the attendant article on Jezebel that turned out to be a rich example of how health writing that appears strong can go wrong: 


...These results don't necessarily mean you can just eat endless Ho Hos and hot fudge and chocolate pudding and lose weight. Dammit! Researchers say that in fact this study doesn't prove a link between eating chocolate often and losing weight.
Almost. Forget for a moment that technically it's true this study can't prove a link.*  No study has ever proved or can ever prove a link or anything else.  We'll leave that for another fussy rant.  Instead, because I used to have to read and grade essays written on statistical and methodological topics (oh there is a purgatory and it's here on earth) I take pride in translating these kind of statements. So I think I know what she meant to say and the researchers reluctantly admitted:

This study doesn't prove eating chocolate causes people to lose weight. 

(Though this didn't prevent researchers from speculating about the compounds in chocolate that might hasten weight loss. Speculation brought to us thanks to mice.)

Despite the journalist's good writing and best efforts to explain the link between chocolate and weight, even her plug for experimental design albeit with an unnecessary placebo (she must have missed the control-group pod cast - a range of other treats/foods would suffice) she still falls for the charm of cause and effect.
If they really want to find out if eating chocolate does make you lose weight, they've got to do a study that's designed to compare chocolate eaters and non-chocolate eaters by giving people placebo chocolate, and they're having trouble figuring out how to make fake chocolate good enough to pass as a placebo. (Well, don't use carob; nobody's gonna buy that.) Still, the basic news is that there is some benefit to be derived from chocolate, and it seems to come from eating it often.
Translation: Basically eating chocolate really does make you skinny. 

Although I worship chocolate at all price points and cocoa contents, this study didn't provide a single scoop of evidence for any benefits, be they physical, spiritual or otherwise.  I didn't want to pay for the journal article but having read several news articles I gleaned this bit of info.  The more chocolate consumed (not sure if freq or amount), the weaker the link between the sugary substance and weight. It's unclear why.  If the miracle fat-dissolving or metabolism-boosting compound works at smaller doses it should at larger ones.  It doesn't appear the researchers found links between total amount of chocolate consumed and weight because all reports talk solely of frequency of consumption.  I find that curious.

Anyone read the actual study? BTW, the skinnier-chocolate eaters didn't exercise more or consume fewer calories - so the subjects said. 
 
Thankfully WebMD had a more nuanced take on the findings, citing skeptical experts including one who ventured that maybe some folks might be thinner and more lax in eating treats.  Someone there had the good sense to at least put a question mark in the headline.  Eat More Chocolate, Weigh Less?
 
So basically, it's what your mom said.  If it's too good to be true...
 
But here's an almost too good to be true.  A professor of nutrition, food studies, and public health at New York University named, I kid you not, Marion Nestle.  She's not related in any way to the behemoth food empire. Nor did she conduct this study. 

Thanks for letting me indulge my chocolate-induced fury.  It's a tiny study that's already generated too much media attention.

*Update: The Wall Street Journal report also says "the researchers caution that the study doesn't prove a link between between frequent chocolate munching and weight loss." Maybe the researchers did actually say this and that's unfortunate.  In any event, they should have said the study didn't show chocolate causes weight loss.  Wonder if the remark came from a university press release.

3 comments:

Becca said...

Truefact: if you get 60% of your calories from fat, you are healthier (e.g. better cholesterol, lower inflammatory markers) if you have chocolate in your diet than if you do not. If you're a mouse.

Barbara said...

Amen. Would that bad reporting of thin research be no more!

Polly Palumbo, Ph.D. said...

I know, as if eating dark chocolate could firm up my #@%. (sorry for the pseudo cuss, mom)