Body Mass Index
The questions used to define the indicator were: How tall are you without shoes? How much do you weigh without clothes or shoes?
For 18 years and over, BMI is calculated as follows: BMI = weight(kg)/height(m)².
Categories for this indicator include: underweight (BMI less than 18.5), healthy weight (BMI from 18.5 to 24.9), overweight (BMI from 25.0 to 29.9) and obese (BMI of 30.0 and over).
Obesity was further classified into: Obesity Class I (BMI between 30.0 and 34.9), Obesity Class II (BMI between 35.0 and 39.9) and Obesity Class III (BMI of 40.0 or over).
For children and adolescents, the same categories are used but they are linked to international cut off points by sex, between 2 and 18 years of age, defined to pass through a BMI of 16, 17, and 18.5 for underweight, 25 for overweight, and 30 for obesity at age 18 years (Cole et al. 2000; Cole et al. 2007).
The validity of self-reported height and weight has been investigated in adult, adolescent, and young adult populations. While many studies have observed a high correlation (96 per cent agreement) between BMI calculated from self-reported and measured height and weight, there is ample evidence that self-reported height and weight is not as exact as measured height and weight but is adequate for conducting epidemiological research.
The indicator covering Overweight or Obesity includes those who are overweight or obese (i.e. with a BMI of 25.0 or higher: overweight (BMI from 25.0 to 29.9) and obese (BMI of 30.0 and over)).
References
Cole T, Bellizzi M, Flegal K, Dietz W. Establishing a standard definition for child overweight and obesity worldwide: International survey. British Medical Journal 2000; 320. Available at
https://www.bmj.com/content/320/7244/1240
(accessed 13 May 2021).
Cole Y, Flegal K, Nicholls D, Jackson A. Body mass index cut offs to define thinness in children and adolescents: International survey. British Medical Journal 2007; 335(7612): 194. Available at https://www.bmj.com/content/335/7612/194 (accessed 13 May 2021).