For decades, researchers had to rely on self-reporting to amass large quantities of data about caloric consumption and calorie-burning exercise. They knew the information was flawed, but were unable to do anything about it. (We’ve started the discussion on this topic in our previous post.)
In 2015 a paper was published that really highlighted the gravity of the situation. A team from the University of Alabama’s Nutrition Obesity Research Center declared that such poor-quality data “no longer have a justifiable place in scientific research.” NPR journalist Eliza Barclay wrote:
That’s some strong language, considering that these data have been used in hundreds of major studies to inform hundreds of public health policies and clinical recommendations… New techniques using digital photography — that’s right, photographing subjects while they eat — and chewing and swallowing monitors show promise. The authors also note that short-term, though expensive, techniques of measuring energy balance in a metabolic ward also give more accurate results.
A 2012 study aimed to both determine whether survey participants are able and willing to self-report, and to assess the accuracy of this self-reporting. The researchers recruited young people between the ages of 16 and 29 from among the throngs of music festival attendants. Among the reported results were these findings:
Overall, 52% accurately self-reported height, 30% under-reported, and 18% over-reported; 34% accurately self-reported weight, 52% under-reported and 13% over-reported.
Males are more likely to overestimate their own height. In both sexes, weight tends to be underestimated. Sadly but (considering societal expectations) not surprisingly, women are twice as likely to under-report their weight.
An enormous 2008 meta-study systematically reviewed the literature “to determine the extent of agreement between subjectively and objectively assessed physical activity in adults.” Throughout the international literature on the subject, it seems there is no more thorough examination anywhere of “the relationship between self-report and directly measured estimates of adult physical activity.”
But despite its comprehensive nature, because of the differences in methodology and so forth, more than anything else this research seems to have highlighted the difficulties of completing such a study. The authors wrote:
At this time, it is not possible to draw any definitive conclusions concerning the validity of self-report measurements compared to various direct methods…
Why do participants prevaricate?
Paul Dolan has written, “Our propensity to cheat, just like our propensity to eat, has less to do with the type of person we are and more to do with the opportunity to do so.” Another suggested explanation is that people simply forget about casually consumed snacks and thoughtlessly quaffed beverages, and “sometimes believe that if something is healthy, the calories don’t count.” Bottom line, they have trouble being honest with themselves and this of course carries over into dishonesty, whether intentional or not, toward the researchers they are working with.
That observation segues nicely into a recommendation of a guide written by Linda Melone, titled “14 Ways You Lie to Yourself About Your Weight.” Of course, ideally a person will learn about these ways not in order to adopt them, but to avoid them. Since self-deception is a game played by almost everyone in our culture, this is a very useful article.
Your responses and feedback are welcome!
Source: “We Lie About What We Eat, And It’s Messing Up Science,” NPR.org, 01/14/15
Source: “Measuring the accuracy of self-reported height and weight in a community-based sample of young people,” BiomedCentral.com, 11/21/12
Source: “A comparison of direct versus self-report measures for assessing physical activity in adults: a systematic review,” BiomedCentral.com, 11/06/08
Source: “Happiness by Design,” Amazon.com, 2015
Source: “To Lose Weight, You Need to Stop Lying to Yourself,” BodyForWife.com, 01/07/15
Source: “14 Ways You Lie to Yourself About Your Weight,” Health.com, 08/26/15
Photo credit: Ferrous Buller (lumachrome) on Visualhunt/CC BY-SA