Understanding the Relationship between Socio-Economic Status, Physical Activity and Sedentary Behaviour, and Adiposity in Young Adult South African Women Using Structural Equation Modelling

Abstract

Socio-economic status (SES) is an important predictor of obesity, but how it is associated with differences in physical activity and sedentary behaviour is less clear. This cross-sectional study examined the association between SES (sum of household assets), physical activity and sedentary time, and how they predict adiposity. Socio-demographic, anthropometric, and physical activity data on rural (n = 509) and urban (n = 510) South African women (18–23 years) were collected. Overweight and obesity prevalence, and sedentary time, were higher; and moderate-vigorous intensity physical activity (MVPA) was lower, in the urban sample. Structural equation models (SEMs) were constructed for BMI and waist circumference. In the urban sample SES had a direct inverse effect on MVPA (ß; 95% CI, −41.69; −73.40 to −9.98), while in the rural sample SES had a direct effect on BMI (ß; 95% CI, 0.306; 0.03 to 0.59). In the pooled sample, SES had a direct inverse effect on MVPA (ß; 95% CI, −144; −170.34 to −119.04), and MVPA was directly associated with BMI (ß; 95% CI, 0.04; 0.01 to 0.08). The influence of SES, and the role of physical activity and sedentary time on adiposity differs between the urban and rural samples, and the importance of other environmental and behavioural factors must be considered in the development of obesity and the design of effective interventions.

Determinants of body mass index by gender in the Dikgale Health and Demographic Surveillance System site, South Africa

“…These findings are supported by a study from Soweto that found a direct association of SES with obesity among rural adult women, but found that among urban women the relationship was mediated by PI [16]. Another study from an urban African township in Cape Town, South Africa, showed that a high SES was associated with obesity in women but not in men [55].…”

“…Furthermore, work and domestic PA were not associated with obesity [39], supporting present findings. The commonly held position that increased physical activity is associated with a decrease in BMI [40,41] is in contrast with studies reporting positive associations between PA and BMI [15,16,42,43]. There is compelling evidence suggesting that PA has no influence of the risk of becoming overweight or obese [14], however, the value of PA on the general state of health is universally accepted [44,45].…”

“…However, some suggest that the Physical Inactivity and Nutritional Transitions are the major causes of obesity [8,13]. Moreover, some cross-sectional and longitudinal studies question the aetiological role of PI, while the role of specific macro-nutrients in the development of obesity remains controversial [14–16]. In addition, factors such as sedentarism, stress, lack of sleep and a cultural belief that bigger-is-healthier have been associated with increased body mass index (BMI) [8,11,17].…”

“…In addition, factors such as sedentarism, stress, lack of sleep and a cultural belief that bigger-is-healthier have been associated with increased body mass index (BMI) [8,11,17]. An independent, positive relationship between socioeconomic status (SES) and BMI was reported in rural but not urban women, suggesting variations between rural and urban areas [16]. Stunting, which is high in African countries, is a significant contributor to obesity in adolescence and adulthood [12].…”

Are fitness club members likely to meet the current physical activity recommendations?

“…Secondly, more than 78% of our participants had college or university education. Studies investigating the general population have shown that higher education levels reflect more favorable lifestyle habits, including participation in regular exercise . Still, a high proportion of our fitness club members (nearly 60%) reported low exercise frequency (<one time a week, or no exercise the last month).…”