Childhood circumstances, social mobility and the obesity transition: Evidence from South Africa

The distribution of obesity tends to shift from rich to poor individuals as countries develop, in a process of shifting sociodemographic patterns of obesity that has been called the 'obesity transition'. This change tends to happen with economic development, but little is known about the specific mechanisms that drive the change. We propose that improvements in childhood circumstances with economic development may be one of the drivers of the obesity transition. We explore whether the social gradient in body weight differs by childhood socioeconomic status (SES), proxied by the respondent's mother having Grade 12, using South Africa's nationally representative panel National Income Dynamics Study. In support of our hypothesis, we find that the social gradient in body weight is less positive for adults who had a high childhood SES, and already appears to have reversed among high-SES women who also had a high childhood SES. Upward social mobility over an individual's life course or across a single generation is associated with higher body weight compared to a stable high SES. But a high SES sustained in childhood and adulthood - or across more than one generation - may decrease adult obesity risk, and result in a reversal of the social gradient in body weight. Random effects within-between models show that the social gradient in body weight and its interaction with childhood SES are driven more by differences in income between individuals than by short-run changes in income within individuals, again suggesting that the obesity transition is driven by long-run changes rather than by very short-run changes. Our results are broadly robust to using several alternative measures of body weight, childhood SES and adult SES. Our results are consistent with the hypothesis that widespread improvements in childhood circumstances and nutrition with economic development may contribute to the shift to later stages of the obesity transition.

Understanding the dynamics of the obesity transition associated with physical activity, sedentary lifestyle, and consumption of ultra-processed foods in Colombia

OBJECTIVE

We investigate the obesity transition at the country- and regional-levels, by age, gender, and socioeconomic status (SES) and its relationship to three health behavior attributes, including physical activity (PA), sedentary activities (ST), and consumption of ultra-processed foods (CUPF) within the urban population of Colombia, from 20,010 to 2050.

METHODS

The study is informed by cross-sectional data from ENSIN survey. We used these data to develop a system dynamics model that simulates the dynamics of obesity by body mass index (BMI) categories, gender, and SES. This model also uses a conservative co-flow structure for three health-related behaviors (PA, ST, and CUPF).

RESULTS

At the national level, our results indicate that the burden of obesity is shifting towards populations with lower SES as the gross domestic product (GDP) increases, particularly women aged 20-59 years with lower SES. Among this group of women, the highest burden of obesity is among those who do not meet the PA, ST and CUPF recommendations. At the regional level, our findings suggest that the regions are at different stages in the obesity transition.

CONCLUSIONS

The burden of obesity is shifting towards women with lower SES as GDP increases at the national level and across several regions. This obesity transition is paralleled by a high prevalence of women from low SES groups who do not meet the minimum recommendations for PA, CUPF, and ST. Our findings can be used by decision-makers to inform age- and SES- specific policies seeking to tackle the obesity.