Waist–Hip Ratio More Appropriate Than Body Mass Index

Letters to the Editor Misclassification of Self-Reported Body Mass Index Categories A Systematic Review and Meta-Analysis by Romy Freigang, Dr. med. Anne-Kathrin Geier, M. Sc. in Public Health, Dr. med. Gordian Lukas Schmid, Prof. Dr. med. Thomas Frese, Prof. Dr. med. Andreas Klement, and PD Dr. rer. nat. Susanne Unverzagt in issue 15/2020

The body mass index (BMI) does not say anything about a person’s body fat distribution. Without having observed a test person physically (either in person or in a photograph), using BMI is of limited relevance even for epidemiological studies. In addition, it can be assumed that quite a few lay people simply calculate their BMI incorrectly or misjudge it. This would easily explain the variability, the risk of bias, and the inconsistency in the results of relevant studies (1).

Even when looking at individual cases, BMI can actually only be used validly if the appearance of the test person is known. The best example are well-trained strength athletes, such as boxers or bodybuilders. Without having specific knowledge about them, these athletes would routinely be classified as obese based on their BMI: an athletic muscular heavyweight boxer who is 2 m tall and has an “ideal” combat weight of 120 kg would have a BMI of 30 (e.g., at the border between being overweight /obese).

For adults who are overweight, having fat at the height of the belly button (waist) increases their risks of developing cardiovascular disease and diabetes mellitus as well as of premature death (2). The so-called waist–hip ratio (WHR) can reveal an unfavorable increase in abdominal fat much better, and is also easier to calculate, than BMI. Interestingly, the self-assessed BMI of participants in a large US study correlates well with certain biomarkers, such as triglycerides and leptin, but less so with a more precise classification of the prevalence of obesity (3). In our opinion, (self) assessment of health risks from obesity would be more accurate if at least both BMI and WHR were always calculated in parallel.

DOI: 10.3238/arztebl.2020.0659a

Prof. Dr. med. Dr. rer. nat. Michael G. Haufs
Faculty of Life Sciences–Department of Health Sciences,
Hamburg University of Applied Sciences (HAW Hamburg), Germany
Facharztpraxis für Dermatologie, Arbeitsmedizin, Allergologie und Umweltmedizin, Münster, Germany

Prof. Dr. rer. nat. York F. Zöllner
Faculty of Life Sciences–Department of Health Sciences,
Hamburg University of Applied Sciences (HAW Hamburg), Germany

References

1. Freigang R, Geier AK, Schmid GL, Frese T, Klement A, Unverzagt S: Misclassification of self-reported body mass index categories—a systematic review and meta-analysis. Dtsch Arztebl Int 2020; 117: 253–60

2. Vague J: The degree of masculine differentiation of obesity: a factor determining predisposition to diabetes, atherosclerosis, gout and uric-calculous disease. Am J Clin Nutr 1956; 4: 20–34

3. McAdams MA, Van Dam RM, Hu FB: Comparison of self-reported and measured BMI as correlates of disease markers in US adults. Obesity 2007; 15: 188–96