Nothing

Calories: Nothing Is Better Than Junk Data

Ask any hoarder. Nothing is better than their junk. And we are collecting a mountain of junk conclusions based upon junk data about dietary intake and energy expenditure — self reports that we know are inaccurate and biased. The International Journal of Obesity has just published a new report in which Obesity Society President Nikhil Dhurandhar and a distinguished group obesity researchers conclude that we should stop relying on this junk data, saying:

While new strategies for objectively determining energy balance are in their infancy, it is unacceptable to use decidedly inaccurate instruments, which may misguide health care policies, future research, and clinical judgment.The scientific and medical communities should discontinue reliance on self-reported EI [energy intake] and PAEE [physical activity energy expenditure].

One of the sources of junk data for energy intake is NHANES, the National Health and Nutrition Examination Survey. For many types of data, NHANES is totally indispensable. But for dietary intake, it reports energy intake that is off by as much as 800 calories per day. And the general credibility of NHANES leads otherwise discerning scientists to accept its dietary data. Routinely, we read scholarly-sounding rationalizations like this one:

Self-report can be adequately objective if sources of nondifferential and differential error have been appropriately adjusted for, allowing less biased estimation of absolute intake and measures of association.

That sounds good, but it’s erudite self-deception. The fact is that people misremember and bias their reports toward what they think they are supposed to be doing. People are more active, eat less junk, eat more “healthy” foods, and take smaller portions in self reports than they do in real life.

So it’s not surprising that a recent analysis of NHANES dietary intake data concluded that more affluent and educated people improved their diet over the last decade. This analysis, published in JAMA Internal Medicine, covered a period when First Lady Michelle Obama was warning us that we better shape up the quality of our diets. Less affluent and less educated people didn’t keep up. Maybe they didn’t get the memo that they were supposed to be reporting better dietary habits.

What is surprising is that JAMA published such conclusions without acknowledging that shifting biases in self reports might account for much or all of the trends observed.

It’s time to start relying on more objective measures of diet and exercise and stop publishing potentially misleading analyses of self-reports.

Just like a hoarder, we need to start tossing out the junk.

Click here to read the report in IJO and click here to read more from ConscienHealth about the recent analysis of NHANES data published in JAMA Internal Medicine.

Nothing, drawing © Khalid Albaih / flickr

Subscribe by email to follow the accumulating evidence and observations that shape our view of health, obesity, and policy.


 

4 Responses to “Calories: Nothing Is Better Than Junk Data”

  1. November 24, 2014 at 9:41 am, Allen Browne said:

    Ted,

    “You go Boy”

    Allen

  2. November 24, 2014 at 10:43 am, Ted said:

    Thanks, Allen!

  3. November 24, 2014 at 11:26 am, Richard Atkinson said:

    Great commentary!

    Dick

  4. November 24, 2014 at 2:15 pm, Ted said:

    Thanks, Dick. And thanks for working on this issue!