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CME slides:

My grand rounds CME slides are now available on Picasa--click the blue box on the top of the right hand column.

Sunday, December 12, 2010

More thoughts on what I should have presented

Note--this is taken from my email response to someone(on the Nutrition and Metabolism Society  list-serv) wondering how my talk went

I think the effect of advice in the public health/pop culture has to be considered, and peoples conceptions of what people actually eat on a low carb diet are skewed.  We told people to eat less fat and eat carbs instead--instead we just ate more carbs.  People think we eat more of everything or are less physically active, but really what has changed has been carbs.  The NHANES data really support this.  I looked at the USDA consumption data as well, and that really backs it up, http://www.ers.usda.gov/Data/FoodConsumption/.  I really tried to point out that low carb diets do not really result in more fat, or at least more saturated fat consumption, do not result in ketosis, and basically decrease only the carbs in the diet and calories, without overt caloric restriction.  I reviewed  large studies only (I stuck to 6 month + studies, which ended up being in Annals of Internal Medicine, JAMA, or NEJM) even though I know that especially in diabetics the data from smaller studies of shorter duration is great.  I wanted to deflect criticisms.  

I did not get into the arguments that ketosis is safe, we know it is, but getting bogged down in "confusing science" during a one hour presentation when hardly anyone in major LC trials gets to ketosis didn't make sense.  The totality of the data supporting weight loss, and when studied, much better diabetic control, is so compelling, it can speak for itself.   Likewise, I did not discuss metabolic advantage or good and bad calories, but if we believe the reported caloric intake in studies, this is also self evident.  Someone asked about it during my presentation ("What is going on with the low carb diet--It is so much more dramatically more effective than the others ? [I had the weight figure up from the JAMA A to Z trial on the screen].   I did not want to get into is a calorie a calorie ? debate.  I questioned the dietary questioning/pointed out that perhaps a LC diet is lower calorie than the other diets despite reported intakes being similar, but said it is an area of great debate, mentioned the 2nd law of thermodynamics but also reminded people of insulin, glycemic index/load, etc.   It takes a whole lecture to do this  topic justice, if you have people who don't remember their second semester biochemistry in the audience.  By the way, the doctor ( a pediatrician) who asked about ""What is going on with the low carb diet ?" was also one who when I was rushed to get through some data introducing the glycemic index, asked why I didn't spend less time on the rest of the talk and more time on this.  I think his first question was rhetorical and he of course knew how the LC diet was working.  I did point out that the glycemic index is not very intuitive, and even the glycemic loads quoted are not based on real world portion sizes, especially in the case of pasta.  

The other audience response of note was basically--we shouldn't diet--we should instead eat whole, real food, Michael Pollan style.  Nothing is wrong with eating this way.  Everybody nods there head and agrees with M. Pollan--nothing is objectionable.  I don't think it translates into concrete recommendations though.  It would lead to overall lower glycemic load and probably more whole grains, fiber, and maybe less carbs, but people only do maybe 50% of what they tell them (look at the NHANES results--increasing carbs but not decreasing fat or in the large LC trials, carbohydrate intake 30-40% of calories by 6 months).  We are doing well to reduce carbs to 40% of calories and make the ones we eat have a lower glycemic index--but to get there, as in the trials, maybe everybody has to say they are following Atkins, when in fact at six months they are following the Zone diet.  

One last thing I presented was just a bit on the saturated fat idea (pointing out the arbitrary choice of countries in the 7 countries study) and the fact that replacing saturated fat with carbohydrates has a negative effect on cardiac event rates.   I really didn't do the saturated fat topic justice.  There were so many things I wanted to say, and only one CME to put it in.  In retrospect I would have cut a few of the LC intervention studies, Presented USDA consumption data or the NHANES data, but not both, and might not have presented the saturated fat idea.  I might have had time to discuss the glycemic index, insulin, and how LC diets are beneficial and have a metabolic advantage vs a similarly low calorie diet with more carbohydrates.  

In my slide set I had the meat vs plant low carb mortality analysis data--the paper was just a crappy analysis of two decades old observational studies, and taking time to point this out wasn't really necessary in my presentation.  I only included it because I thought people would wonder why I did not discuss this--because the study was picked up in the popular press as "meat kills."  I never realized how much and pre-emptive defense of one's thesis and points goes into deciding what to put into a presentation there is, especially on a relatively controversial topic such as dietary recommendations and different macronutrients.

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