Defining morbid obesity in children based on BMI 40 at age 18 using the extended international (IOTF) cut-offs

Pediatr Obes. 2014 Oct;9(5):e94-8. doi: 10.1111/j.2047-6310.2014.00217.x. Epub 2014 Feb 27.


Background: Studies have reported that children who are obese are becoming more severely obese.

Objective: We aimed to classify obese children based on age- and gender-specific centile curves passing through body mass index (BMI) 30, 35 and 40 at age 18 as 'class I', 'class II' or severe, and 'class III' or morbid obesity.

Methods: In addition to the International Obesity Task Force BMI cut-offs corresponding to BMI 30 and 35, we calculated the BMI cut-offs corresponding to BMI 40 using the LMS method proposed by Cole and Lobstein. We classified 217 obese children according to these criteria.

Results: Fifty-six (25.8%) children had class III obesity, 73 (33.6%) class II obesity and 88 (40.6%) class I obesity. Class III obese children had a higher waist circumference, systolic blood pressure and fasting insulinaemia compared with less obese children.

Conclusion: It is clinically important to classify obese children in different classes of obesity severity.

Keywords: BMI; children; morbid obesity; reference values.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Blood Pressure
  • Body Composition*
  • Body Mass Index*
  • Child
  • Child, Preschool
  • Disease Progression
  • Female
  • Humans
  • Male
  • Obesity, Morbid / classification*
  • Obesity, Morbid / diagnosis*
  • Obesity, Morbid / epidemiology
  • Prevalence
  • Reference Values
  • Risk Factors
  • Severity of Illness Index
  • Waist Circumference*