Why everything we think we know about nutrition is wrong

Oh boy. If you’re looking for a little chuckle, have I got the story for you.

According to a recent news article I read, the nutritional insights we’ve collected from the National Health and Nutrition Examination Survey (NHANES) over the last 40 years don’t mean squat.

No, really. This research is completely useless when it comes to informing either public policy or dietary guidelines.

Why? As it turns out, a new study has found that the self-reported data upon which NHANES is based doesn’t offer an accurate picture of what (or how much) Americans actually eat.

I just have to laugh at this.

Of course self-reported dietary data isn’t accurate.

Whenever I ask a patient what they eat (something I do pretty much all the time), they invariably start off by saying what they generally eat for lunch or breakfast.

It’s only when I ask them specifically–as in, what did you actually eat today–that I begin to get a real idea of what they’re really consuming. (And that’s assuming that they’re not forgetting–or “conveniently forgetting”–anything.)

It doesn’t take a genius to reach the conclusion that self-reported food intake is almost always underreported. Not that this little detail has kept the federal government from allocating 90 percent of its nutrition and obesity research budget toward collecting and evaluating data using these invalid methods.

So here we are, funneling funding into poorly designed research on “energy intake.” When we could be spending time and resources on legitimate strategies to fight obesity.

I mean, is it any wonder that this country just keeps getting fatter?

And it’s not like this is some earth-shattering new discovery, either. We’ve known that nutrition surveys are inherently flawed for at least 20 years. Yet NHANES (which, by the way, is our major source for nutritional information of any kind) doggedly persists in using them.

With the end result, of course, that everything we think we know about diet is essentially meaningless–being based on 40 years of worthless science.

I could tell you how this particular study came up with its conclusion. But I won’t bore you with the details. Because the bottom line–that we’re using 1950’s methodologies in a 21st century, computer-controlled world–is what matters, here.

That’s one of the reasons NHANES has gone on a downward spiral.

Information about the right way to eat is accessible to just about everyone in this day and age.

Which is great, of course. But it also means people can lie on surveys to make their diet look better than it actually is.

Though for the record, I don’t think all of the NHANES inconsistencies are the result of deliberate lies.

At the end of the day, it also boils down to participants’ ignorance regarding portion size and other details about the food they consume. (Which, all-too-frequently, happens to be prepackaged and heavily processed.)

All of this is tragically, typically American. We know what’s good for us. And we want the world to know that we know. Yet, we still find it so hard–near impossible, really–to implement this knowledge in our daily lives.

It doesn’t have to be this way. But if we insist on continuing to delude ourselves, I certainly don’t expect it to change anytime soon.

“Validity of U.S. nutritional surveillance:National Health and Nutrition Examination Survey caloric energy intake data, 1971-2010.” PLoS One. 2013 Oct 9;8(10):e76632.
NHANES Diet Data: ‘Pseudoscience’ Informs US Policy. Medscape. Oct 16, 2013.