Elsevier

Nutrition

Volume 18, Issue 5, May 2002, Pages 422-427
Nutrition

Nutrition in Africa
Physical inactivity is the major determinant of obesity in black women in the North West province, South Africa: the THUSA study

https://doi.org/10.1016/S0899-9007(01)00751-1Get rights and content

Abstract

OBJECTIVE: We investigated the association between measures and determinants of obesity in African women.

METHODS: For a cross-sectional study of adult black women in the North West Province, South Africa, we used a stratified sample of 1040 volunteers from 37 randomly selected sites in the province according to the level of urbanization. We analyzed the association between measures of obesity, namely body mass index (BMI), waist circumference, waist-to-hip ratio, triceps and subscapular skinfolds, and socioeconomic factors, dietary intakes, and physical activity.

RESULTS: The rate of obesity (BMI > 30) in the sample was 28.6%. We found a significant positive association between household income and measures of obesity. After exclusion of underreporters and adjustments for age, smoking, and household income, we found significant positive correlations between total energy intake, fat intake, and BMI. Physical activity index (derived from a subset of 530 subjects) correlated negatively with BMI and waist circumference. Subjects in the highest third of physical activity were less likely to be obese (odds ratio-0.38, 95% confidence interval-0.22–0.66).

CONCLUSIONS: Women with higher incomes and lower physical activity were at the greatest risk of increased BMI. Physical inactivity showed the strongest association with measures of obesity in this study.

Introduction

There is an exceptionally high prevalence of obesity among black South African women.1, 2 The reasons for this phenomenon are not well understood. It seems that many black South African women do not want to lose weight because obesity is culturally and esthetically looked upon with far less disfavor in black women than in white women.3 Factors such as higher parity and lower levels of physical activity may contribute to the tendency of black women to gain weight.4 Increased body mass index (BMI) among women is associated with chronic diseases, especially coronary heart disease. Results from the coronary artery risk development in young adults (CARDIA) and atherosclerosis risk in communities (ARIC) studies have shown that black and white women should avoid excess adiposity.5 To prevent and treat obesity in black women, more should be known about the underlying causes of obesity among these women to develop appropriate and culturally accepted interventions.

The Transition and Health During Urbanisation of South Africans (THUSA) study assessed the relation between stratum of urbanization and measures of health status in the black population of the North West Province. This part of the study investigated the association between measures of obesity and factors contributing to obesity such as socioeconomic factors, dietary intakes (total energy, total fat, percentage of energy from fat, total carbohydrate, and sugar), and level of physical activity.

Section snippets

Subjects

Strata of urbanization had to be defined to plan the drawing of a sample from the study population. The definitions of urban and rural used in epidemiologic research should be determined by the aim of the study.6 Given the aim of the THUSA study, subjects who stayed only temporarily in the city or a rural area were not included in the study sample. In addition to two rural strata (people living in tribal areas and on farms), three different strata of urbanization were distinguished for urban

Demographic data

The demographic data of the subjects showed that most spoke Setswana (75.7%), with a low level of school education (53.7% primary school or less), a high unemployment rate (64.3%), and a low household income (77.4% less than R1000, or US $130, per month). There were no significant differences between the demographic profiles of subjects in the 1996 and the 1998 surveys.

Socioeconomic data

There were significant differences between the BMI, TSF, SSF, and WHR of subjects in the different income groups (P < 0.01).

Discussion

We assessed the association between measures of obesity and socioeconomic factors, dietary intakes, and physical activity. The prevalence of obesity (BMI > 30) in the THUSA study sample was slightly lower than that reported for black South African women in the Cape Peninsula1 and the Free State.2 The mean BMI values of the three study samples are compared in Table V.

It was not possible to measure the skinfold thicknesses of grossly obese subjects with calipers because such measurements were

Conclusion

The subjects most at risk of being obese were those from the higher income categories and habitual low physical activity. These findings are consistent with the results of Paeratakul et al.17 in a Chinese population. Weak, but statistically significant, positive correlations between total energy and fat intakes and BMI were found. The highest fat intakes in this study were in subjects living in urban areas. A high fat intake and a high energy intake may be among the contributing factors to the

Acknowledgements

The authors gratefully acknowledge the assistance of all members of the THUSA research team, especially Dr. A Kruger, for drawing of blood samples, Professor J. H. de Ridder for supervision of the anthropometrical measurements, and Dr. U. E. MacIntyre for supervision of the dietary assessment. Support with statistical analyses was received from Professor H. S. Steyn, DSc, of the Statistical Consultation Service, Potchefstroom University for CHE, who was responsible for drawing the sample. The

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  • Cited by (0)

    Editor: Demetre Labadarios, MB, ChB, PhD, FACN

    This project was supported by research grants from the South African Sugar Association, the National Research Foundation of South Africa, and the Research Fund of the Potchefstroom University for Christian Higher Education.

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