Obesity trends and risk factors in the South African adult population.

Annibale Cois,Candy Day

doi:10.1186/s40608-015-0072-2

Annibale Cois, Candy Day

Open Access

https://doi.org/10.1186/s40608-015-0072-2

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Journal: BMC obesity	Publication Date: Oct 13, 2015
Citations: 123	License type: cc-by

Affiliation: University of Cape Town, Health Systems Trust

Abstract

BackgroundObesity prevalence is increasing globally and contributes substantially to the burgeoning burden of non-communicable diseases. South Africa is particularly affected by this increasing trend and cross-sectional evidence suggests socioeconomic and behavioural variables as possible drivers. However, no large scale longitudinal study has attempted the direct identification of risk factors for progression towards obesity.MethodsThis study analysed data on 10,100 South African adults (18 years and over) randomly selected in 2008 and successfully recontacted in 2010 and 2012. Latent Growth Modelling was used to estimate the average rate of change in body mass index (BMI) during the study period, and to identify baseline characteristics associated with different trajectories.ResultsThe overall rate of change in BMI during the study period was +1.57 kg/m2 per decade (95 % CI: 0.93 −2.22), and it was higher among women (+ 1.82 kg/m2 per decade, 95 % CI: 1.06 −2.58) than among men (+ 1.03 kg/m2 per decade; 95 % CI: 0.14 −1.93).Female gender, younger age, larger waist circumference, white population group and higher household income per capita were baseline characteristics associated with higher rates of change.The association between tobacco use and obesity was complex. Smoking was associated with greater waist circumference at baseline but lower rates of increase in BMI during the study period. Quitting smoking was an independent predictor of BMI increase among subjects with normal weight at baseline.Among subjects with baseline BMI lower than 25 kg/m2, rates of changes were higher in rural than urban areas, and inversely related to the frequency of physical exercise.ConclusionsA strong positive trend in BMI remains in South Africa and obesity prevalence is likely to increase. Trends are not homogeneous, and high risk groups (subjects with high socioeconomic status, rural dwellers, young women) and modifiable risk factors (physical inactivity) can be targeted. Subjects quitting smoking should receive additional weight-loss support in order that the numerous health benefits of cessation are not reduced by increasing BMI. Centrally obese subjects should be targeted in campaigns.Electronic supplementary materialThe online version of this article (doi:10.1186/s40608-015-0072-2) contains supplementary material, which is available to authorized users.

Highlights

Obesity prevalence is increasing globally and contributes substantially to the burgeoning burden of non-communicable diseases
The Southern African region1 is affected by this rising trend in body mass index (BMI), and within this region South Africa — a middle income country undergoing rapid epidemiologic transition — shows an especially worrying picture
The aim of this study was to take advantage of longitudinal data collected by the Southern Africa Labour and Development Research Unit (SALDRU) during the first three waves of the National Income Dynamics Study (NIDS) to contribute to fill this knowledge gap and improve the understanding of the current trends in obesity in the South African population and its determinants

Summary

Introduction

Obesity prevalence is increasing globally and contributes substantially to the burgeoning burden of non-communicable diseases. The Southern African region is affected by this rising trend in BMI, and within this region South Africa — a middle income country undergoing rapid epidemiologic transition — shows an especially worrying picture. The rate of growth, calculated over the period between 2000 and 2008, was 2.9 kg/m2 per decade for males and 1.6 kg/m2 per decade for females, with a remarkable increase compared to the preceding period 1980 to 2000, when the average rates of growth were 0.7 kg/m2 and 0.65 kg/m2 per decade, respectively among males and females [1] These high values of BMI and seemingly increasing growth rates have an obvious correspondence with a large and rapidly increasing proportion of people overweight or obese. In the decade between 1998 and 2008, the estimated proportion of the South African adult population who was overweight or obese increased from 29.1 to 31.1 % among males (+6.9 % in relative terms), and from 56.2 to 59.5 % among women (+5.9 %) [2]

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