Date Published: August 31, 2017
Author(s): Violet Kankane Moselakgomo, Marlise van Staden.
This study was designed to estimate overweight and obesity in school children by using contrasting definitions recommended by the Centers for Disease Control and Prevention (CDC) and the International Obesity Task Force (IOTF).
The sample size consisted of 1361 learners (n = 678 boys; n = 683 girls) aged 9–13 years who were randomly selected from Mpumalanga and Limpopo provinces of South Africa. A cross-sectional and descriptive design was used to measure the children’s anthropometric characteristics. Based on height and weight measurements, the children’s body mass index (BMI) was calculated and used to classify them as underweight, overweight and obese. Percentage body fat was calculated from the sum of two skinfolds (i.e. triceps and subscapular). Age-specific BMI, percentage body fat and sum of skinfolds were examined for the boys and girls.
A higher prevalence of overweight and obesity was found in boys and girls when the CDC BMI categories were used. In contrast, the IOTF BMI classifications indicated a strong prevalence of underweight among the children.
In contrast to the IOTF index that yielded a greater occurrence of underweight among South African children, the CDC criteria indicated a higher prevalence of obesity and overweight among the same children. Future large-scale surveillance studies are needed to determine the appropriateness of different definitions in order to establish a more reliable indicator for estimating overweight and obesity in South African children.
Excessive body fatness has arguably become a paediatric health problem in developed nations. Excess body fat constitutes a serious risk to health1, affecting the physiological functions and physical fitness of an individual,2,3,4,5,6 and could negatively influence physical performance by having deleterious impact on mechanical, metabolic and thermoregulatory attributes of an activity.7,8 For example, in the United Kingdom, estimates of excessive childhood body fatness have increased from 2.0-fold to 2.8-fold in 10 years.9 Furthermore, in the United States, overweight or obese children are at risk of developing cardio-metabolic complications.10,11
The study estimated body weight and fatness using CDC and IOTF classifications among 1361 primary school children (boys, n = 678; girls, n = 683) aged 9–13 years in Mpumalanga and Limpopo provinces of South Africa. Participants’ anthropometric measurements according to gender are presented in Table 1.
The results of this study provide information on estimating body fatness using different definitions among rural primary school children aged 9–13 years from two South African provinces. Estimating body weight disorders using the CDC and IOTF BMI-based methods has become a hypothetical viewpoint. In previous studies, comparisons between countries were hindered by the use of diverse criteria for describing overweight and obesity.23,24,25,26,27,28,29,30,31,32,33,34,35 Furthermore, age- and gender-related BMI percentiles used for evaluating body weight disorders in children could be regarded as a right set of measure to screen an individual’s levels of obesity or thinness, thereby providing data that could be helpful to detect body weight related health problems. In a study carried out among a sample of Portuguese school age children, it was stated that the age- and gender-related BMI percentiles for screening for body weight disorders clearly distinguish BMI criteria for children.6
In conclusion, this study indicated a considerably higher level of underweight in South African school children when IOTF criteria were used. Specifically, 67.9% of boys and 79.6% of girls were classified as underweight. In contrast to IOTF benchmark, the CDC standards yielded higher prevalence of overweight (boys: 9.94%; girls: 10.4%) and obesity (boys: 5.46%; girls: 5.31%) among the children. Therefore, these results support the hypothesis that the CDC and IOTF BMI classifications would yield discrepant estimates of obesity and overweight among the South African children. In view of the divergent estimates of the children’s body weight and fat characteristics found in this study, it is important that large-scale surveillance studies carried out to estimate body weight disorders among children should provide clear rationale for the choice of cut-off points. This is necessary to minimise errors that could confound data analysis and interpretation, consequently questioning the reliability and validity of such estimates.