Level of agreement between objectively determined body composition and perceived body image in 6- to 8-year-old South African children: The Body Composition–Isotope Technique study

Abstract

To assess the level of agreement between body size self-perception and actual body size determined by body mass index (BMI) z-score and body fatness measured by the deuterium dilution method (DDM) in South African children aged 6-8 years. A cross-sectional sample of 202 children (83 boys and 119 girls) aged 6-8 years from the Body Composition-Isotope Technique study (BC-IT) was taken. Subjective measures of body image (silhouettes) were compared with the objective measures of BMI z-score and body fatness measured by the DDM. The World Health Organization BMI z-scores were used to classify the children as underweight, normal, overweight, or obese. DDM-measured fatness was classified based on the McCarthy centile curves set at 2nd, 85th and 95th in conjunction with fatness cutoff points of 25% in boys and 30% in girls. Data were analyzed using SPSS v26. Of 202 children, 32.2%, 55.1%, 8.8%, and 2.4% perceived their body size as underweight, normal, overweight, and obese, respectively. Based on BMI z-score, 18.8%, 72.8%, 6.9%, and 1.5% were classified as underweight, normal, overweight, and obese, respectively. Body fatness measurement showed that 2.5%, 48.0%, 21.8%, and 29.7% were underweight, normal weight, overweight, and obese, respectively. The application of silhouettes and BMI zscores resulted in either overestimation or underestimation of own body size. Overall, the levels of agreements (kappa, κ) between body size perception, body fatness, and BMI for age respectively, were small (κ = 0.083, p = 0.053 and κ = 0.154, p<0.001). Level of agreement between body size perception, body fatness, and BMI z-score was poor. The use of silhouettes made children either overestimate their own body size while being underweight or underestimate their own body size while being overweight or obese. Given the potential

Association between Objectively Determined Physical Activity Levels and Body Composition in 6–8-Year-Old Children from a Black South African Population: BC–IT Study

“…The current study follows a cross-sectional design and is descriptive in nature. It forms part of a larger study on BC using the isotope technique (BC–IT) [ 5 ]. The larger study examines the relationship between objective (stable isotope) and indirect (anthropometric variables) measures of BC indices and objective (accelerometer), and subjective (physical activity questionnaire for older children (PAQ-C)) measures of PA among 6-to-8-year-old South African children, and the relationships with other health-related determinant factors (blood pressure, lifestyle habits).…”

“…The decline in physical activity (PA) levels in children has been linked to a high prevalence of obesity and overweight [ 1 , 2 , 3 ]. In recent regional studies in South African children and adolescents, a high prevalence of obesity and physical inactivity were reported [ 4 , 5 ]. In sub-Saharan Africa, the prevalence of overweight and obesity increases over time during childhood and is more prevalent in girls compared to boys [ 6 , 7 ].…”

“…In sub-Saharan Africa, the prevalence of overweight and obesity increases over time during childhood and is more prevalent in girls compared to boys [ 6 , 7 ]. If overweight and obesity are not identified early in life and preventative measures are not put in place, physical inactivity and excess adiposity in childhood can have long-lasting negative health effects [ 5 , 6 , 7 , 8 , 9 , 10 ]. Furthermore, childhood obesity is associated with an increased risk of morbidity and mortality later in life—it accounts for as much as 20% of cardiovascular deaths in midlife [ 11 ].…”

Birth Weight and Body Composition as Determined by Isotopic Dilution with Deuterium Oxide in 6- to 8-Year-Old South African Children

“…In this study, a cross-sectional descriptive study design was used in a sub-sample of 91 children (40 boys and 51 girls) from a larger study on body composition, using a stable isotope technique (BC–IT study) [ 23 , 24 ]. The 91 participants were included because they had complete retrospective BW (primary exposure) data recorded from their Road-to-Health cards (RtHC) ( Figure 1 ).…”

“…This sample size was, however, largely dependent on the availability of a completed RtHC birth record for each child and should not be viewed as a representation of children in the age groups. More details about the BC–IT study have been published elsewhere [ 23 , 24 ].…”