Friday, November 28, 2014
This is the title of a recent article by Nikhil Dhurandar and other members of the Energy Balance Measurement Working Group (of which I am a member), published in the International Journal of Obesity and refers to the inadequacies of our current methods for assessing energy intake and expenditure.
In the paper, the authors argue that while an assessment of energy balance may well be a critical issue both for research and clinical practice, our current methods for assessing this are woefully inaccurate and may well be leading us in the wrong direction.
Thus, for example, there is no shortage of information on the fact that self-reported dietary energy intake (EI) is woefully inaccurate (despite all efforts over the past decades to try and make this more accurate) to the point of being near useless in individuals and even less meaningful in population studies – at least when it comes to the assessment of energy balance.
The same is unfortunately true for assessments of physical activity energy expenditure (PAEE) where errors ranging in the 100s of calories are the norm rather than the exception.
This leads the authors to the rather sweeping conclusion that,
“…self-reports of EI and PAEE are so poor that they are wholly unacceptable for scientific research on EI and PAEE. 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 and PAEE.”
While this may well hold true for research, I am not that sure about the implications for clinical practice.
This is because, the very act of self-monitoring has been shown to influence behaviour – irrespective of the precision of such monitoring (at least I am not aware of a single study showing that the accuracy of food records makes any difference to the outcome).
There is indeed overwhelming evidence that patients who use any form of self-monitoring (pen and paper or electronic) eat better and are more physically active than people who don’t.
While trying to determine someone’s precise energy balance by poring over these records is a rather futile exercise (the difference between the records and what actually happens may be in the 100s of calories), I do know that my patients who keep food and activity records do better than those who don’t.
Nevertheless, as far as research is concerned (or making clinical decisions based on assuming that the actual energy balance is anywhere close to the deceptively precise numbers calculated from such record), I agree with the authors that our current methods are highly inadequate and, what is worse, may well be misleading.
I, for one,happily ignore most of the data that comes from self-reported studies on diet or activity (which, incidentally is the vast majority of research on these issues), never mind that much of these data come from epidemiological studies, where any inference of causality is speculation at best.
On the other hand, precise or not, I do encourage all of my patients to self-monitor as I know this changes behaviour – no matter if these records are off by 100s of calories.
Dhurandhar NV, Schoeller D, Brown AW, Heymsfield SB, Thomas D, Sørensen TI, Speakman JR, Jeansonne M, & Allison DB (2014). Energy balance measurement: when something is not better than nothing. International journal of obesity (2005) PMID: 25394308