Members of UK parliament have called to avoid using body mass index (BMI) as a marker of health because it would inspire “weight stigma, contributes to eating disorders, and can damage an individual’s body image and mental health” (1). While BMI is appealing because it is easy to measure, it is notoriously a peculiar health indicator, and not a simple marker of adiposity and related health risk (2).
Despite its limitation as a health indicator, I argue that BMI could be considered as an intersting socio-economic indicator.
On the one hand, BMI is the result of a multilevel, environmental, socioeconomic, and life course interplay of causal factors. This may explain why it relates in a very complex way with various health outcomes and mortality. For instance, there is a U-shape relationship between BMI and mortality, with an optimum level changing with age - high BMI being a weaker predictor of increased mortality in older compared with younger individuals (2, 3).
On the other hand, the socio-economic patterning of obesity is well documented (4). In high-income countries, high BMI is more frequent among the less wealthy, while the reverse is true in numerous low- and middle-income countries. The increase in mean BMI has also followed the socio-economic development in many countries worldwide and, notably by the concomitant reduction in the prevalence of underweight, is a favorable trend. It could therefore be wiser to use BMI as a socio-economic indicator, at an individual and at a population level, rather than a mortality or any other health outcomes predictor.
References
1. Mahase E. Stop using body mass index as measure of health, say MPs. BMJ. 2021 Apr 9;373:n941.
2. Hugues V. The big fat truth. Nature 2013; 497:428-30.
3. Chiolero A. Why causality, and not prediction, should guide obesity prevention policy. Lancet Public Health 2018; 3(10):e461-e462.
4. McLaren L. Socioeconomic status and obesity. Epidemiol Rev 2007; 29:29-48.
Competing interests:
No competing interests
18 April 2021
Arnaud Chiolero
Prof of Public Health and Epidemiologist
Population Health Laboratory (#PopHealthLab), University of Fribourg
Rapid Response:
Body mass index as socio-economic indicator
Members of UK parliament have called to avoid using body mass index (BMI) as a marker of health because it would inspire “weight stigma, contributes to eating disorders, and can damage an individual’s body image and mental health” (1). While BMI is appealing because it is easy to measure, it is notoriously a peculiar health indicator, and not a simple marker of adiposity and related health risk (2).
Despite its limitation as a health indicator, I argue that BMI could be considered as an intersting socio-economic indicator.
On the one hand, BMI is the result of a multilevel, environmental, socioeconomic, and life course interplay of causal factors. This may explain why it relates in a very complex way with various health outcomes and mortality. For instance, there is a U-shape relationship between BMI and mortality, with an optimum level changing with age - high BMI being a weaker predictor of increased mortality in older compared with younger individuals (2, 3).
On the other hand, the socio-economic patterning of obesity is well documented (4). In high-income countries, high BMI is more frequent among the less wealthy, while the reverse is true in numerous low- and middle-income countries. The increase in mean BMI has also followed the socio-economic development in many countries worldwide and, notably by the concomitant reduction in the prevalence of underweight, is a favorable trend. It could therefore be wiser to use BMI as a socio-economic indicator, at an individual and at a population level, rather than a mortality or any other health outcomes predictor.
References
1. Mahase E. Stop using body mass index as measure of health, say MPs. BMJ. 2021 Apr 9;373:n941.
2. Hugues V. The big fat truth. Nature 2013; 497:428-30.
3. Chiolero A. Why causality, and not prediction, should guide obesity prevention policy. Lancet Public Health 2018; 3(10):e461-e462.
4. McLaren L. Socioeconomic status and obesity. Epidemiol Rev 2007; 29:29-48.
Competing interests: No competing interests