Monday, January 28, 2008

Quick Update

Just a quick note of a number of things I've been reading in the last day or so:

Cholesterol - I'm still a sceptic

What’s Cholesterol Got to Do With It? - Gary Taubes looks at the recent news that the drug Vytorin had fared no better in clinical trials than the statin therapy it was meant to supplant.

Trial results forced out of drug company support the concept that cholesterol may not ’cause’ cardiovascular disease - Dr John Briffa comments on the same topic

Do Cholesterol Drugs Do Any Good? - Research suggests that, except among high-risk heart patients, the benefits of statins such as Lipitor are overstated - similar article from Business Week

and on a different subject:

Cutting caffeine may help control diabetes - “We’re not sure what it is about caffeine that drives glucose levels up, but we have a couple of theories,” says Lane, who is the lead author of the study. “It could be that caffeine interferes with the process that moves glucose from the blood and into muscle and other cells in the body where it is used for fuel. It may also be that caffeine triggers the release of adrenaline – the ‘fight or flight” hormone that we know can also boost sugar levels.” I've mentioned coffee and blood sugar before

Gulp - Controversy!

Finally, prompted by Randy's comments on this post, I've been reading a little about the alleged so-called metabolic advantage of low carb diets. This is the idea that weight loss is not just about creating a calorie deficit, but that the composition of your diet can have an effect independent of the calories. Bluntly put it holds that not all calories are equal in their effect. I didn't realise quite how controversial this idea was.

In the post in question I didn't actually mention metabolic advantage, I merely pointed to an interesting article by Gary Taubes, who believes in this idea. Randy took me to task over this (!) and directed me to Anthony Colpo's book They are all MAD. Colpo's assertion is that in all the metabolic ward studies where they lock people up for a couple of months and feed them diets of known composition and quantity and control their activity, the only thing that mattered ultimately is the calorie - if you take in more than you burn you put on weight....He holds that low carb diets are still healthier than the alternatives, but they only help you lose weight because you end up eating fewer calories.

There is another side to this of course (there always is!) I'm not an expert and wouldn't want to be dogmatic about all this (so don't be too hard on me Randy!) but in addition to Colpo's book I've looked at Barry Groves comments (do calories really count), Michael Eades posts (here and here) and a couple of scientific papers (e.g. this and this)

Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression - Conclusion: Low-carbohydrate, high-protein diets favorably affect body mass and composition independent of energy intake, which in part supports the proposed metabolic advantage of these diets.

Low-carbohydrate nutrition and metabolism - This review article also discusses the proposed metabolic advantage


Anyway - this is a controversial topic that seems to get people really agitated. I just find all this stuff fascinating. This blog is just me gathering together bits and pieces that I find interesting. Feel free to disagree with me.

17 comments:

Anonymous said...

Have to agree with Randy. For a blog that purports to cover science, and generally does a good job, you have been blinded by the pseudoscience of Taubes, Eades, and others trying to sell books. Please focus on the research and not the marketing hype.

terrence said...

Please don't be swayed by ad hominem attacks on Taubes, Eades, and others, Chris. The science these guys write about is clear and very well documented.

Anonymous said...

Chris,
Your counter points hold no substance (please excuse me for being blunt and no disrespect)

The articles by Eades, and Groves were empty opinion pieces that ignored the massive empirical data published in peer review journals and didn't offer any counter human data of their own.

The articles by Feinman (atleast he's a real scientist) were theoretical considerations that also ignored the metabolic ward data. Feinman has been taked to task for this failure in the professional press. See my earlier post

The review article you provided was a meta-analsys that also ignored the ward studies and limited itself to "free living" reports of what folks eat. This is known to be unreliable and there are studies demonstrated how useless this information can be. (I'll provide them if you wish).

The other study you provided didn't even test the hypothesis, but showed that human metabolism with burn what you feed it.


The ultimate way to test the Metabolic Advantage Theroy is to strickly control exactly what subjects eat as regards calories and macronutrient mixture. These types of studies are VERY expensive but there have been about 20 done in the last 65 years and the results or virtually unanimous - Only calories count!

For instance, take some subjects and lock them up. Feed half a zero carb diet and the other half a 85% carb diet at the same calorie level(or combination you want) for a month. Then switch the subjects to the opposite diet for a month. When this is done and its been done many times in the last 50 years there is no difference weight gain or loss.

Can you tell me why these studies don't trumpt mere opinion pieces or weakly controlled data by subjects on the "honor system".

Still love your site and I appreciate all the hard work you put into it.

Kind Regards
Randy

Chris said...

Anon 1 said "Please focus on the research and not the marketing hype."

er? I really do not understand that comment. What "marketing hype" did I post above? Links to a couple of blogs and a couple of scientific research papers?

I am lost by that comment! I've linked to Colpo's MAD thing too. Is that marketing hype? He is selling books as well remember.

Chris said...

"you have been blinded by the pseudoscience of Taubes, Eades, and others trying to sell books"

This is wild. What in particular prompted that comment?

Anonymous said...

Change gear here.
Most of the negative takes on coffee as far as I know are based on data obtained with caffeine supplement, which is quite different from coffee. I think it has been shown that coffee improves insulin sensitivity because of magnesium, zinc, ...

Chris said...

Re caffeine - I think you are right - the research seems to go backwards and forwards on this.

NHS Choices had a good analysis of this research:

http://tinyurl.com/2wwnku

in this case the research was about beverage consumption rather than cafeine tablets:

"A questionnaire asked the participants to report their usual drink consumption and this was used to calculate their average daily caffeine intake as 520mg per day, with a wide variation in the amount individuals took."

CR said...

"...you have been blinded by the pseudoscience of Taubes, Eades, and others trying to sell books."

I love those kinds of comments, as if these other "scientists" and their studies are done without bias or goals other than pure knowledge.

Anyone who knows the history or sociology of science and research knows that's laughable.

There are books written to make money, and there is science done to make money (or gain prestige, or grants or further employment).

If you want to attack the arguments made by an author, then present counter-arguments. Dismissing the validity of someone's ideas or arguments simply because they find resonance in the public discourse is intellectual laziness.

CR said...

An anecdote from Taubes (via Seth's Blog):

There’s a group at the University of Cincinnati that did an Atkins vs. low-fat study and they found that the Atkins people lost twice as much weight and they liked the diet much better. I was interviewing the dietitian who did the study. She had agreed to talk to me but she was very hesitant — she didn’t offer up any information. Finally, at the end of the interview, the one thing she offered freely: I asked her who funded it and she said the American Heart Association.

I said, “Well, I have to give them credit for funding it.”

She said, “Don’t. They funded it because we proposed it as a study that would refute the benefit. And when we found that the Atkins diet really worked and worked better than the low-calorie diet, now we’re trying to get money to look further into it and they won’t give it to us.”

Chris said...

Good points CR.

Dr Biffa had a related post last week -

http://tinyurl.com/ysb6ch

"imagine for a moment a cardiovascular department in a University is looking to fill a professorial chair. And imagine a substantial part of the funding for the relevant department comes from a drug company that make statin (cholesterol-reducing) drugs. Now, imagine there are two candidates for this post: candidate A who is known to be staunchly supportive of statins; and candidate B who has publicly expressed doubts about them, and has suggested they are not as effective and are generally more toxic than we have been led to believe.

Now think for a moment who, all other things being equal, is most likely to get the job? You might imagine that learning of the candidates, the drug company who funds the department might have quiet word in the ear of the University Dean to make it clear that if candidate B were to be appointment, funding would be withdrawn. Without the funding, there may be no professorial chair or department at all.

This is of course an entirely hypothetical situation, but believe me when I tell you that there is considerable potential for just this sort of thing to happen in the real world. And because of it, it can sometimes be very difficult to get what approximates as the truth from an ‘expert’, however eminently qualified."

Tony Kenck said...

Colpo has his own commercial incentives as well. In MAD, he has a link to his Fat Loss Bible, where for only $39.95 you can learn the secrets that the other guys missed.

Even at the start of that page though he cites a controlled study where people followed different diets (Zone, Learn, Ornish, Atkins). Atkins beat the others by about double. Colpo's take was "...I'd immediately fire any trainer who could only achieve a piddling 4.7 kg weight loss in his clients after a full year!"

I am not qualified to judge his stuff, nor does he make it available for free, but he is at least as biased as anybody.

Chris said...

Cheers Tony.

Anonymous said...

Please point to the articles on this site (or any other) that discuss the metabolic ward studies proving a metabolic advantage for LCDs and specifically reducing body fat. Those tightly controlled diet studies are really the only ones that can be trusted. The study that Tony references has already been shown to have significant flaws and it really doesn't prove the case as he suggests (read the whole thing not the abstract). Chris is pushing the paleo diet on this site despite the lack of any research whatsoever.

Chris said...

This is getting boring. We have been through this a few times now. Have a look at my latest post - it might explain things better.

I'm not "pushing" anything, just pointing to things I find interesting. If you don't like it, fair enough...its my blog.

As for paleo diet research:

http://tinyurl.com/39vf4q

http://tinyurl.com/ynwpqx

there is lots more research out there too....(for and against of course!)

CR said...

It does begin to take on the characteristics of a political or religious argument.

You've got the Fat-o-fascists on one side, or the Carb-o-fasicsts on the other, and everyone starts yelling.

Now I'm basically a paleo-fascist, because the research I'm seeing that I find credible (based on my own bias) is making it more and more clear that the whole low-fat, high-carb diet fad* is not only not effective, but extremely harmful.

(*Yes, of all the so-called diets, low-fat, high-carb about the most faddish, since it't the most recent, and the one least tested by evolution over a few thousand generations.)

It's really difficult for me to see how people can continue to deny that, but then again, these kinds of paradigms get deeply embedded into cultural consciousness, and it's very difficult to overcome the inertia and crowd-following effects.

And I've never understood the counter-argument that low-carb, high-fat diests work because you consume less calories. So? Isn't that a good thing, then? (If you believe that lowering calorie intake is a good thing.)

But yeah, it is boring, and I don't think anyone posting here is going to have their minds changed. However, some of those on the sidelines might be led to look into the issue more deeply, and that's a good thing.

It is interesting how emotionally committed some people get to what should be scientific questions. But that's the history of science, to be sure. (See Kuhn, Thomas.)

Chris said...

Kuhn - that takes me back!

I did a course on the History and Philosophy of Science at university 20 odd years ago an found Kuhn really interesting. Popper was right in theory, but in practice science works like Kuhn says. It is all about the paradigm that you are working in.

Cheers

Anonymous said...

Hey Chris, I noticed you cited one of James Krieger's studies as evidence in favor of the "Metabolic Advantage" theory. I thought you should know, however, that Krieger wrote an article saying he no longer supports the conclusions he came to when writing that study:

http://weightology.net/?p=321

The main thing is that he, like most of the low-carb advocates, relied on self-reported food intakes of free-feeding individuals, and it is common knowledge that people tend to drastically underreport their calorie intakes when on low-carb diets, which is why only metabolic ward trials are actually valid because that's the only way to truly know how much people are actually eating.

The truth is that Colpo is 100% right, low-carb diets are valuable because protein and fat are so much more satiating than carbs and naturally induce a caloric deficit in people, but when isocaloric intakes are forced on people, it makes no difference how many carbs you are eating. Even Dr. Eades now admits that if there is any hypothetical "Metabolic Advantage", it's so insignificant it can't even be measured on a scale

Low-carb diets certainly have value, but not because of some mythical "Metabolic Advantage" or their magical ability to control insulin