Because obesity can lead to several health complications, including type 2 diabetes, high blood pressure, cancer, or joint disease, it is important to regularly assess its prevalence, as well as that of overweight in the population. These prevalences are generally obtained in adults by measuring the body mass index (BMI) which is based on the collection of measurements of height and weight.
But analyzes carried out on a sample of nearly 2,500 adults aged 18 to 74, included in the health study on the environment, biomonitoring, physical activity and nutrition (Esteban 2014-2016) show that basing on “reported” height and weight measurements without verifying them can partially skew BMI numbers. Because men and women all have the unfortunate tendency of under-declaring their weight and over-declaring their height. In other words, we see ourselves taller and thinner than we really are.
“This difference between declared corpulence and measured corpulence leads to an underestimation of the BMI of the order of -0.41 in men and -0.79 in women” underline the researchers from Public Health France in the last Weekly epidemiological bulletin. “The researchers also found that the differences between what people say and what is observed were greater in overweight or obese people. “These differences were particularly significant for the prevalence of obesity, which was reduced by 5 points when it was estimated in comparison with measured data (-5.3 points in men and -4.6 points in women and up to -6.9 points in 55-74 year olds)” they explain .
Public health issues
“The results of this study highlight significant reporting biases in body weight data reported among adults in the general population. In general, men and women overestimate their height and underestimate their weight, in the order of +0.37 cm and -0.75 kg for men and +0.70 cm and -1.40 kg for women” note the researchers from Public Health France. These discrepancies lead to an underestimation of BMI, which in turn leads to an underestimation of the prevalence of obesity in the population. The researchers therefore recommend more regular monitoring (every 5 years) with effective anthropometric measurements, “so as to provide precise information on the prevalence of overweight and obesity in the population and to assess the impact of the public health programs implemented in place to fight this epidemic”.
Source :
Differences between declared and measured corpulence in population surveillance studies in FranceBEH, June 29, 2021
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