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Welcome all seeking refuge from low carb dogma!

“To kill an error is as good a service as, and sometimes even better than, the establishing of a new truth or fact”
~ Charles Darwin (it's evolutionary baybeee!)

Saturday, June 30, 2012

The Great Calorie Debate -- A YOUNG biophysicist weighs in

Hat tip to Colby Vorland (@nutsci) via Twitter:  New fuel for the calorie debate

This is the blog of one Carson Chow -- half of the dynamic duo who set one Mr. Gary Taubes straight for once and for all about glycerol-3-phosphate -- and routinely puts the man to shame.  Oh ... but let it never escape your mind that Chow is *young* ... I hear he's even more *young* than I am *female*!!

In any case, Chow picked up on something that I missed in my obsession with the statistics.  The average TEE's measured by doubly labeled water were:  LF / LGI / LC =  2812 / 2937 / 3137 (by FQ) and = 2767 / 2926 / 3013 (by RQ).  The average caloric intake was 2626 calories per day.  This was less than each of the average TEE's for each diet by either measure.  By a minimum of 140 calories per day, to over 500 calories per day.   On average, everyone would have been in caloric deficit and lost something over 12 weeks, yet they didn't lose weight.  Heck, I suppose that's something for the CDS sufferers to hang their hats on.   Chow seems to attribute this more to error in TEE measurement, and I'll add that cheating cannot be ruled out either.

Oh ... interestingly enough, they reported energy intake as is customary, Mean (SD) -- 2626(686).  But no such transparency for EE's which are reported Mean [95% CI Range].  Sigh.

And oh again ... re-reading, it was the other half, (rumor has it he's still young too), Kevin Hall, that picked up on this. 

13 comments:

ProudDaddy said...

When I suggested measurement error in my 6/30 comment, I thought I probably had committed some sort of major heresy and would quickly be handed my head on a platter. Nice to know that I may not be the only item on the serving tray!

ProudDaddy said...

I like people who think straight, or at least try to. Carson Chow has been added to my RSS feed, and there's a lot of his blog on my to-read list. Thanks for pointing him out!

Evelyn aka CarbSane said...

Measurement error is something that flies under the radar and is not included in any statistical error. Mostly it is assumed that such error has equal probability of being high or low and it balances out in the wash and it "must" be small if they're using a tried and true method. There's a lot of variability of reporting of this sort of error, too, as well as whether it is considered, or attempts made to convey that it was. Just the other day I read a small study where they measured REE with one of those "desktop" units and they went to great pains to discuss how the instrument was calibrated and how they retested some subjects to assess variability. So when they reported a significant change in REE they pointed out the magnitude of that difference vs. potential measurement error or day-to-day variation. I haven't really looked into it too closely, but I've seen it stated that REE can vary day-to-day between 2-to-5 percent. Coupled with the measurement error, that really puts the supposed 65 or so cal/day estimated difference in context -- that's 4% of the measured REE, and that test lasted 20 min in this study (too lazy to check that right now). With a sample this small, you're darn tooting these other errors could have produced the outcomes we saw.

Hall really hit on something embarrassing for the authors of this study. They didn't notice that the measured TEE exceeded the reported intake by as much as 500 cal/day. This was measured over 2 weeks. If this were true, it would be reflected in weight. Speaking of which, the margin of error in the weights is 4.1 lbs = ~9 lbs which is 4.5% of their mean weight and roughly 1/3rd of the mean weight loss. Were they weight stable??? We can't tell that from the data presented but they mentioned that intake would not be altered in the test phases regardless of fluctuations in weight, so did they? I'm beginning to think that they didn't construct a proper data table because it wouldn't make for good optics.

This study is more and more horrible the more I think about it. And lost in all of this is how little it means even if it had been perfect in every other way. They looked at short term maintenance on diets that differed from the diet used to lose weight to make recommendations for the best maintenance diet because recidivism rates are so high for obesity. So now the LC'ers will claim in their books that you have a higher metabolic rate on low carb. That explains why it's so much easier for low carbers to maintain their weights, eh?

ProudDaddy said...

BTW! Carson Chow may be just as young as you are. His "About" says he has worked on biological problems for close to twenty years.

Simon Carter said...

Dr. Chow is 49 years old as stated in this interview in the New York Times,
http://www.nytimes.com/2012/05/15/science/a-mathematical-challenge-to-obesity.html?_r=1&ref=science

Evelyn aka CarbSane said...

Thanks for this info guys!

Chow's age is interesting, he likely looks younger and this betrays Taubes' biases. Taubes almost always refers to Hall & Chow as the two YOUNG biophysicists. In his lectures he quotes tens of scientists by name but in Q&A's and interviews he refers to scientists he's spoken to by descriptives -- which is why I used to call Keith Frayn the English guy, that's who he was for several months. These two may look 20 years or perhaps more his junior, but that SHOULD be irrelevant. Taubes mentions their supposed youth to diminish them. In one interview (I've listened to a lot recently) he said "two bioph... two young biophysicists" ... it's important to him that his audience associate youth with these two. This is done to plant the seed in his audience's minds that they lack experience or perhaps even knowledge. That Chow is not even a decade his junior is quite interesting indeed.

Signed, (formerly) anonymous female blogger

George Henderson said...

But wasn't the point to MAINTAIN the weightloss, to measure what happens in a steady state? One thing this experiment was never designed to be, was a comparison of the weightloss effects of the diets.
What I take home from this is the obvious; there is a "metabolic advantage" in terms of greater energy loss through heat generation on VLC diets.
Whether this is really an "advantage" in weight loss terms - why it should differ from energy lost by exercise or fasting - no-one knows.
I like to think thus (which is honestly the way most of our hypotheses should be phrased in our current state of knowledge): the real "advantage" from VLC comes through a pharmacological effect of ketones on metabolically damaged neurons.
If you have this damage, you benefit from ketosis, at least up the point where the damage is reliably reversed.

You can nitpick absolutely any experiment for size, duration; these things are expensive and hard for participants to sustain. This is as good as it gets at the moment, and better than most. The difficulty of conducting a study as one would have liked should never be taken as license to interpret the results as one would have liked them to be.

Evelyn aka CarbSane said...

George ... They maintained with each diet. Period. Damage schmage, missing calories expended or not. Or am I "nitpicking"??

I and most others will give you this: ketosis can and generally does suppress appetite for a good long time. But some do not even experience a transient suppression of appetite. Really! And if we're talking long term, a 4 week study period when longer studies have been conducted makes this pretty useless. Right? Or am I just nit picking?

Evelyn aka CarbSane said...

BTW, I do not reject this study for the sample size limitations. But I do for some of the things they didn't measure. Surely you can agree that if the point was to study maintenance, the absolutely A number one, ONLY most importantist thing in the whole wide scientific world would have been to make sure they were in maintenance, right? FAIL on that front, because THEY DIDN'T EVEN BOTHER TO MEASURE THAT. And then they compare 4 weeks on varying diets vs. pre-weight loss measures which I might remind were obtained for all manner of their usual diets.

But eh ... this is really the BEST we can do? No it's not.

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