The gap between obesity levels measured by self-reported height and weight and obesity recorded by measured height and weight is increasing. This is due to an increasing bias in self-reported weight, according to research published January 23 in the open access journal PLOS ONE by Frances Shiely and colleagues from University College of Cork, Ireland.
BMI is a ratio of height and weight used clinically to assess whether an individual's weight is in a healthy range. Previous studies have shown that people tend to over-estimate their own height and under-estimate their weight and it is generally assumed that both are responsible for under-estimation of self-reported BMI. The authors of this study have shown in previous work that under-estimation of BMI is increasing over time. Here, they assess whether this increasing inaccuracy is due to changing biases in self-reported height, weight, or both, using data from a representative sample of Irish adults.
The researchers found that the bias in self-reported height has remained stable over the last ten years regardless of gender, age or clinical BMI category. However, biases in self-reported weight have increased over time for both genders and in all age groups. The bias towards reporting a lower weight is most notable in those who are obese.
The authors state that knowing why self-reported BMI scores are decreasing while clinically measured BMIs are not "brings us one step closer to accurately estimating true obesity levels in the population."
The above story is based on materials provided by Public Library of Science. Note: Materials may be edited for content and length.
- Frances Shiely, Kevin Hayes, Ivan J. Perry, C. Cecily Kelleher. Height and Weight Bias: The Influence of Time. PLoS ONE, 2013; 8 (1): e54386 DOI: 10.1371/journal.pone.0054386
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