Are Dietary Recommendations Wrong? Inconvenient Data

The blog-o-sphere is certainly replete with interesting theories, regardless of whether they're backed by data. One that I hear constantly is that the dietary guidelines make us sick/fat/diabetic/obese/etc etc. With the recent Annals of Internal Medicine low carb publication, I saw a particularly substantial number of people making claims that recommendations to choose a low-fat diet made us fat. I have a lot of issues with taking a reductionist viewpoint with regard to dietary recommendations, because they were never to 'just' reduce fat intake. But let's play along.

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The line of thinking that backs this can be found in this chart:

The first dietary guidelines came out in 1980 and advocated reducing fat consumption. If you look at this chart, it appears that this coincides with the obesity epidemic. Does correlation equal causation?  I hope not, or else Nick Cage has some explaining to do:

Spurious Correlations: http://www.tylervigen.com/

A little piece of the data that individuals like to forget to include are these graphs (2,3):

For reference, 1MJ = 239kcals

Around this same time, the amount of food/number of calories available to individuals also increased. And Americans certainly didn't let all of that increase spoil: they ate a lot of it. The increase in total calories consumed is more than sufficient to explain the amount of weight gained during US obesity epidemic - a summary of this data can be found here.

But we were told to reduce fat? We replaced fats with carbs and that made us fat, right?

It turns out that we never hit the low-fat goals (4). While the percentage of total kcals coming from fat dropped slightly, we also drastically increased our total kcals, indicating that we didn't reduce our fat intake, but stayed about the same or even increased it.

Between 1971 and 2000, here's what happened to our macronutrients as percentages of kcals (5):

   

One can see slight shifts in the percentage of total kcals, but nothing drastic by any means. Americans never consumed the recommended low-fat diet. And they certainly didn't limit their calorie intake.

It's not just me who is saying this either - the IOM acknowledged it in their 2005 report on Macronutrients:

Also, it wasn't just the low-fat recommendations that haven't been followed (6):

Americans don't really seem to follow the guidelines much at all. While it looks like they're consuming enough in the grains category, .9oz of the estimated 7.5oz consumed per day are whole grains - not even close to the modest recommendation of consuming at least 3oz of whole grains per day (6). And a lot of those grains appear to be incorporated into desserts (7) - nowhere in the guidelines does American intake appear to match what the guidelines state:

When people joke about eating dessert first, I don't think this is what they meant..

The other thing that sparked me to make this post was a new Nutrition Reviews publication that examined population adherence to US federal nutrition guidelines (8). The review looked at articles published between 1992 (the year the Food Guide Pyramid was published) and October 2013, looking at studies of adherence to guidelines and knowledge of guidelines. It focused in on both the FoodGuidePyramid and MyPyramid (no studies on adherence to MyPlate recommendations specifically were available). Food Guide Pyramid studies showed mixed results, but pretty consistently demonstrated low consumption of dairy, fruit and vegetables, regardless of demographics. Overall, longitudinal results indicated that adherence to the Food Guide Pyramid didn't change over time. My Pyramid studies also demonstrated poor adherence, though there were fewer studies. Participants in these studies consumed ranges from no one adhering to all recommendations, to 33.6%. Overall, no positive relationship was observed between knowledge of guidelines and adherence to guidelines. This leaves public health officials and policy makers in quite the predicament...Hopefully future data from MyPlate will indicate better adherence? As of now, little has seemed to work.

It blows my mind how many individuals, even researchers and physicians I see online, talking about how the dietary guidelines make us fat, and the recommendation to eat low-fat caused the obesity epidemic. I'm all for having scientific discussion about optimal macronutrient distributions, and one can certainly debate the benefits of one style of eating versus another - I am of the opinion that the diet that is best is the one that an individual can adhere to (9), though hopefully, research dollars will be funneled towards nutrigenomics research, identifying why individuals respond better to one macronutrient distribution than another and we can one day give more specific recommendations - I wonder what adherence would be if we told individuals that a certain diet was best for their genes #Paleo.  Dietary paradigms and health movements that predicate themselves on 'low fat' made us fat are misrepresenting what recommendations actually were, and the reality of what has happened over the past 30-40 years. The guidelines were never as reductionist as many have interpreted them to be, and never advocated for a diet high in low-fat, high sugar/refined grain calories - I've covered that discussion here.

1. http://www.ncbi.nlm.nih.gov/books/NBK19623/figure/chartbook.f7/?report=objectonly
2. http://www.usda.gov/factbook/chapter2.pdf
3. http://ajcn.nutrition.org/content/90/6/1453.long
http://onlinelibrary.wiley.com/doi/10.1111/nure.12140/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false
4. http://ajcn.nutrition.org/content/93/4/836.full.pdf+html
5. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5304a3.htm#fig1
6. http://www.ers.usda.gov/media/210681/eib33_1_.pdf
7. http://www.health.gov/dietaryguidelines/dga2010/dietaryguidelines2010.pdf
8. http://onlinelibrary.wiley.com/doi/10.1111/nure.12140/abstract
9. http://www.nejm.org/doi/full/10.1056/NEJMc1204792