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Asia Pacific J Clin Nutr (1996) 5(4): 226-228

Body composition of different ethnic groups in South Africa

AJS Benadé DSc, A Oelofse MSc, M Faber MSc

National Research Programme for Nutritional Intervention, Medical Research Council, Tygerberg, South Africa

Plenary lecture presented at an APCNS Satellite Meeting of the Asian Congress of Nutrition on "Nutrition, Body Composition and Ethnicity" in Tianjin, China on 5th October 1995.

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South Africa is in a state of nutrition transition. As with other societies this is reflected in the emergence of overfatness, sometimes in conjunction with protein malnutrition. These phenomena may be expressed differently in a multi-ethnic society like South Africa with its major ethnic groups (Blacks, Whites, Coloureds and Indians) having varied socio-economic status. National population-based studies of coronary risk factors between 1979 and 1991 have been accessed for anthropometric data as weight and height. Cut-off points for overweight have been applied, to children to age 10 as weight-for-height greater than two Z scores by NCHS reference standards, and to those older than 15 and up to 64 years of age, BMI ³ 25 and < 30, and obese ³ 30 kg/m². Data have been stratified by ethnicity, age, gender and place of residence (urban or rural) Urban Black children seem already to have a problem of overweight with a prevalence of 6-18%. For men, urban Whites have the highest prevalence of both overweight (50% in the 45-54 age group) and obesity (20% in the 55-64 age group) in all age groups except the 55-64 age groups for obesity, where Blacks have the higher prevalence (about 29%). Interestingly, the prevalence of overweight in rural women overall (39-52%) exceeds that for urban women (23-31%), although this is not the case for obesity, (prevalence age 25 and beyond, rural 24-39% and urban, 25-60%) where, indeed, in the 45-54 and 55-64 age groups, the urban prevalence exceeds the rural. This raises questions about the factors which reduce or facilitate the transition from overweight to obesity. Urban Black women seem at particular risk of this overweight-to-obesity shift and are known to have a very energy-dense diet. The extent to which overfatness contributes to other coronary risk factors is worth further investigation, given this appears to be less for Blacks than other ethnic groups.

Key Words: Body composition, ethnicity, South Africa, overweight, obesity, children, adults

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Introduction

Overweight and obesity are known to be related to degenerative diseases such as 1000 atherosclerotic cardiovascular disease, hypertension, diabetes mellitus, gall-bladder disease and certain cancers. Anthropometric information from several South African studies indicates a high prevalence of overweight and obesity in adult males and females from various population groups residing in both urban and rural areas. Although early evidence of overweight and obesity is also evident in children younger than five years, undernutrition, as manifested by the presence of underweight and retarded growth, appears to be the major nutritional problem in this age group in South Africa.

This article uses available anthropometric information from various studies conducted in South Africa to obtain a comprehensive picture of the prevalence of overnutrition in South Africa.

Methods

Prevalence data for overweight and obesity in different population groups in South Africa were obtained from four major studies conducted between 1979 and 1991. These studies were primarily conducted to assess the coronary risk factor profiles of four main population groups in South Africa, namely Blacks (BRISK study)^l, Whites (KORIS study)², Coloureds (CRISIC study)³, and Indians⁴. Information pertaining to children under five years of age was obtained from unpublished studies recently conducted by the Medical Research Council⁵.

Criteria for estimating overweight and obesity in the various age groups were as follows:

• 0-10 years age group: Weight-for-height exceeding 2 Z scores, according to the NCHS reference standards, was considered to be overweight.
• Adolescents and adults: Body mass index (BMI) was calculated as weight (kg)/height² (m). Cut-off points for obesity were BMI ³ 30 for all subjects and for overweight at 30 >BMI ³ 25 for men and 30 >BMI ³ 24 for women.

Results are presented as the percentage of individuals overweight or obese according to the above criteria and for the various racial groups residing in rural or urban areas.

Results

Age group 0-10 years: The limited information available for this group suggests that between 2 and 10% of urban Coloured children and between 6 and 18% of urban Black children are either overweight or obese (Figures 1 and 2).

Figure 1. Percentage urban males either overweight or obese. (Z > 2 or BMI>24).

Whites: no children; >15 years: KORIS;
Blacks: children: Kayamandi / >15 years: BRISK;
Coloureds: children: Scottsville/Cloetesville / >15 years: CRISIC

Figure 2. Percentage urban females either overweight or obese. (Z > 2 or BMI>24)

Whites: no children; >15 years: KORIS
Blacks: children: Kayamandi / >15 years: BRISK
Coloureds: children: Scottsville/Cloetesville / >15 years: CRISIC

Overweight in the 15-64 year age group (Figures 3 and 4): The prevalence of overweight shows a clear tendency to increase with age in all ethnic groups, in both males and females. The prevalence of overweig 1000 ht was highest in White males for all age groups, while the prevalence of overweight among Indian women exceeded that for the other ethnic groups in the 35-64 year age group.

Figure 3. Percentage urban overweight males. (BMI between 25 and 30)

Whites: KORIS; Blacks: BRISK; Coloureds: CRISIC

Figure 4. Percentage urban overweight females. (BMI between 24 and 30)

Whites: KORIS; Blacks: BRISK; Coloureds: CRISIC

Figure 5 shows the prevalence of overweightness in urban and rural females. The prevalence of overweightness among rural women is almost double that observed in urban women.

Figure 5. Percentage urban versus rural overweight females (BMI between 24 and 30).

Rural: Ndunakazi; Urban: BRISK

Prevalence of obesity: Obesity tends to increase with age in both males and females (Figures 6 and 7). The prevalence of obesity in women was about two to three times higher than that found in men. More Black and Coloured women were found to be obese than either White or Indian women.

Figure 6. Percentage urban obese males (BMI > 30)

Whites: KORIS; Blacks: BRISK; Coloureds: CRISIC

Figure 7. Percentage urban obese females (BMI > 30)

Whites: KORIS; Blacks: BRISK; Coloureds: CRISIC

When prevalence rates for obesity among rural and urban Black women were compared, far more urban than rural women were found to be obese, especially after the age of 45 years (Figure 8).

Figure 8. Percentage urban versus rural obese females (BMI > 30)

Rural: Ndunakazi; Urban: BRISK

Discussion

A feature of the results reported by the different South African studies on different ethnic groups is the increase in the prevalence of both overweight and obesity with age in both males and females. In males and females of all ethnic groups, overweight was found to increase about two-fold after the age of 25. The prevalence of overweight was found to be very similar in males and females after the age of 25, apart from Blacks. It is interesting to note that although more White males were overweight than any of the other groups, Indian women had a prevalence rate of overweight almost double that observed in White women^2,4 of 25 years and older.

Obesity was found to be rare in males of all ethnic groups. More women than men tended to become obese as they grew older. The highest prevalence of obesity was found among the Black and Coloured groups, especially after the age of 25 years.

An interesting feature of our data is the higher prevalence of obesity among urban Black women after middle age, as compared to rural Black women of the same age range. Although the reason for this is not known, changes in dietary and exercise patterns associated with urbanisation are likely explanations. Urbanised Blacks are known to consume a much more energy-dense diet⁶ than rural populations⁷. If more energ ce0 y-dense food is consumed by the already overweight progress to obesity is more likely.

Although some relationship appears to exist between overweight/obesity and certain risk factors for cardiovascular disease, such as elevated blood cholesterol and high blood pressure in White males and females, Black males and females have lower prevalence rates for all three major risk factors compared with Whites, Indians and Coloureds¹. The high prevalence of overweight and obesity in Blacks therefore does not appear to be associated with an increase in the prevalence of risk factors for coronary heart disease as observed in the other population groups. This issue should be investigated further.

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Body composition of different ethnic groups in South Africa

AJS Benadé, A Oelofse, M Faber

Asia Pacific Journal of Clinical Nutrition (1996) Volume 5, Number 4: 226-228

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References

1. Steyn K, Jooste PL, Bourne L, et al. Risk factors for coronary heart disease in the Black population of the Cape Peninsula. S Afr Med J 1991; 79: 480485.
2. Jooste PL, Steenkamp HJ, Benadé AJS, Rossouw JE. Prevalence of overweight and obesity and its relation to coronary heart disease m the CORIS study. S Afr Med J 1988; 74: 101104.
3. Steyn K, Fourie J, Rossouw JE, et al. Anthropometric profile of the Coloured population of the Cape Peninsula. S Afr Med J 1990; 78: 68-72.
4. Seedat YK, Mayet FGH, Khan S, et al. Risk factors for coronary heart disease in Indians in Durban. S Afr Med J 1990; 78: 447454.
5. Benadé AJS, Oelofse A, Faber M. Unpublished data.
6. Bourne LT, Langenhoven ML, Steyn K, et al. Nutrient intake in the urban African population of the Cape Peninsula, South Africa. The BRISK study. Central Afr J Med 1993; 12: 238-247.
7. Langenhoven ML, Wolmarans P, Groenewald G, et al. Nutrient intake and food meal patterns in South African population groups. Front Gastrointest Res 1988; 14: 4148.

Copyright © 1996 [Asia Pacific Journal of Clinical Nutrition]. All rights reserved.
Revised: January 19, 1999 .

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