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Moqueem, Erum (2020) Improved characterisation of measures of fatness and metabolic risks in older adolescents and young adults in the South Asian population in the UK. Doctoral thesis, London Metropolitan University.
Increasing concerns about obesity and related metabolic risk have demanded better measures to identify individuals who are at higher health risk. This is particularly important in minority ethnic groups, especially those with a South Asian (SA) heritage. Variation in body composition between ethnicities is important in identifying risk. For example, South Asians have a characteristic body composition with a higher proportion of body fat, lower skeletal muscle mass (SMM) and a tendency to accumulate body fat (BF) in the abdominal region at equivalent BMI’s compared with those of a Caucasian heritage. The higher percentage of body fat (BF%) in SA children tends to track into adult life and consequently increases the risk of type 2 diabetes and cardiovascular disease. Across infancy, childhood, adolescence and even young adulthood, overweight and obesity are defined using statistically derived cut-off values, typically using centile charts based upon age and gender specific reference data. It remains a challenge to define optimum reference cut-offs for any body composition or anthropometric variable because of the age-related changes in growth and body composition which occurs during the growth and maturation. In view of this continuing challenge, the aim of this study was to extend the work previously undertaken in this research group to develop a full range of growth references for better characterisation of body composition in the UK SA population for the 4-21 years age range. Up until now, there had been a gap in data for adolescents and young adults between 16 to 21 years of age, hence the objective of this study was to generate SA- specific centile curves for anthropometric measurements (height, weight, BMI, waist circumference (WC), leg length and sitting height) and body composition measures (fat mass (FM, BF%), fat-free mass (FFM) and skeletal muscle mass (SMM) between the ages 16 to 21 years.
This was a field-based study where anthropometric measurements of 546 participants were collected from volunteers from a SA background living in the UK. Single-frequency bioelectrical impedance analysis technology was used for assessment of body composition. Body composition and anthropometric data were used to construct the gender and ethnic specific centile curves using the LMS method for all variables. Comparison of centile charts with equivalent data for Caucasians was performed.
It was found that mean height (172.5 cm for male, 159.3 cm for female) for both genders and mean weight for female (57.8 kg) of the population group was lower (as determined by numerical difference in SD score) compared to the UK 1990 reference. Sitting height increased with increasing age whereas there was no or minimal increase in leg length with increasing age. Participants from the SA ethnic group had (numerically) higher WC and slightly high BMI compared to reference population. At equivalent BMIs, SA tended to have a greater WC. BF% in females increased steadily from 6 to 21 years of age while in males BF% decreased after puberty, most likely reflecting the sex hormone driven changes in body composition during adolescence. FM (kg) increased with increasing age and was similar in both genders. At the 50th centile, SA had a lower SMM compared with Caucasians for all age groups in both genders.
In conclusion, this study provides a range of assessment tools in the form of SA specific reference centile charts for children, adolescents and young adults in the UK and are the first set of reference centile charts for anthropometric measurements and body composition in this population group. The findings indicate that the pattern of body composition and anthropometry differs in the SA population compared to their UK Caucasian counterparts. These reference charts will allow health practitioners and researchers to measure and plot child and adolescent growth, development and measures of metabolic risk for this population group, allowing for comparisons with reference data for the same gender and age.
Available under License Creative Commons Attribution Non-commercial No Derivatives 4.0.
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