Socioeconomic status, economic insecurity and the obesity transition in South Africa : generational and life course aspects

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dc.contributor.advisorVon Fintel, Dieteren_ZA
dc.contributor.authorRich, Kate Tamarinen_ZA
dc.contributor.otherStellenbosch University. Faculty of Economic and Management Sciences. Dept. of Economics.en_ZA
dc.date.accessioned2023-03-03T12:33:31Z
dc.date.accessioned2023-05-18T07:03:57Z
dc.date.available2023-03-03T12:33:31Z
dc.date.available2023-05-18T07:03:57Z
dc.date.issued2023-03
dc.descriptionThesis (PhD)--Stellenbosch University, 2023.en_ZA
dc.description.abstractENGLISH SUMMARY: Worldwide countries are undergoing the ‘nutrition transition’ – a shift towards diets high in saturated fat, sugar and cheap processed energy-dense foods, with a corresponding increase in rates of obesity. The rich tend to move through the transition ahead of the poor, and with this the burden of obesity tends to shift from the rich to the poor as countries develop, in a process that has been called the ‘obesity transition’. This dissertation explores several aspects of the social gradient in body weight in South Africa using the nationally representative National Income Dynamics Study (NIDS) data, proposing that changes across and between generations and over the life course may be one of the drivers of the shift from one stage of the obesity transition to the next. Chapter 2 explores the possibility that childhood socioeconomic status (SES) and intergenerational mobility may contribute to the reversal of the social gradient in body weight. I find that upward social mobility is associated with increased obesity risk in adulthood compared to individuals who maintained a stable high SES in childhood and adulthood. Furthermore, the social gradient in body mass index (BMI) is flatter among individuals from a high SES childhood background, and already appears to have reversed among women with a high childhood SES who also have a high SES in adulthood. These findings shed light on the future of the obesity transition in South Africa; they suggest that it may take more than one generation of sustained high SES – or perhaps of adequate childhood nutrition – before we see higher adult SES have a protective effect against obesity, and with it a plateau in obesity rates. Chapter 3 investigates generational aspects of the obesity transition, proposing that younger generations may be the first to see a reversal in the social gradient in body weight as they experience the benefits of upward intergenerational mobility and with it new circumstances and attitudes. I use a machine learning algorithm to find structural breaks in the social gradient in BMI by birth year. I find that the social gradient in BMI is flatter among younger cohorts of South African men, and find some indications that it is flatter among younger cohorts of women too, suggesting that the obesity transition may be driven in part by changes across generations. Chapter 4 asks whether economic insecurity is more strongly associated with body weight for those with higher levels of income, which yield increased access to excess energy. I find evidence that economic insecurity is more likely to be associated with higher BMI among higher-income women, while economic insecurity is not associated with higher BMI for men. These results suggest that, given continuing high rates of undernutrition in early life and rising living standards, obesity rates in South Africa are likely to continue to rise, particularly for those from low-SES childhood backgrounds. This calls for policies to attempt to reduce consumption of unhealthy foods, and to improve nutrition in childhood – particularly in the earliest years of life.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Lande wereldwyd ondergaan tans die ‘voedingsoorgang’ – ’n verskuiwing na diete hoog in versadigde vet, suiker en goedkoop geprosesseerde energie-digte kosse, met ’n verwante toename in die voorkoms van vetsug. Die rykes neig om voor die armes deur die oorgang te gaan, en dus is die vetsuglading besig om te skuif van die rykes na die armes tesame met ekonomiese ontwikkeling, in ’n proses wat die ‘vetsugoorgang’ genoem word. Hierdie proefskrif ondersoek verskeie aspekte van die sosiale gradient in liggaamsgewig in Suid-Afrika deur die gebruik van die nasionaal-verteenwoordigende NIDS data. Dit stel voor dat veranderinge oor en tussen geslagte, asook veranderinge in die lewenssiklus een van die oorsake kan wees van die verskuiwing van een fase van die vetsugoorgang tot die volgende. Hoofstuk 2 ondersoek die moontlikheid dat kinders se sosio-ekonomiese status (SES) en intergeneratiewe mobiliteit tot die omkeer van die sosiale gradient in liggaamsgewig bydra. Ek het gevind dat opwaartse sosiale mobiliteit met hoer risiko van vetsug geassosieer is, in vergelyking met individue wie ’n stabiele hoe SES in beide die kinderjare en volwassenheid behou. Verder is die sosiale gradient in die liggaamsmassa-indeks (LMI) platter tussen individue van ’n hoe-SES kinderjarige agtergrond, en blyk asof dit reeds omgekeer het tussen vroue met ’n hoe kinderjarige SES wie ook ’n hoe SES in volwassenheid het. Hierdie bevindinge dui daarop dat dit meer as een geslag van volhoue hoe SES mag neem, of moontlik van voldoende voeding in die kinderjare, voor hoer volwasse SES met laer risiko van vetsug geassosieer word, en Suid-Afrika daarmee ’n plato in die voorkoms van vetsug bereik. Hoofstuk 3 ondersoek generasie-aspekte van die vetsugoorgang. Dit stel voor dat jonger geslagte die eerste mag wees om ’n omkeer van die sosiale gradient in liggaamsgewig te ondervind, as hulle die voordele van opwaarts intergeneratiewe mobiliteit en nuwe omstandighede ervaar, en nuwe houdings ontwikkel. ’n Masjienleer algoritme word gebruik om strukturele breke in die sosiale gradient in LMI per geboortejaar te vind. Ek bevind dat die sosiale gradient in LMI platter onder jonger kohorte van Suid-Afrikaanse mans is, en vind sommige aanduidings dat dit ook platter onder jonger kohorte van vroue is. Dit dui daarop dat die vetsugoorgang gedeeltelik deur veranderinge oor generasies gedryf mag wees. Hoofstuk 4 vra of ekonomiese onsekerheid ’n sterker assosiasie het met liggaamsgewig vir die met hoer inkomstevlakke, wat hoer toegang tot oortollige energie gee. Ek vind bewyse dat ekonomiese onsekerheid neig om ’n hoer assosiasie met LMI te he onder hoërinkomste vroue, terwyl ekonomiese onsekerheid nie met hoer LMI onder mans geassosieer is. Hierdie resultate dui daarop dat, gegee die aanhoudende ondervoeding in die vroee jare en stygende lewenstandaarde, die voorkoms van vetsug in Suid-Afrika waarskynlik sal aanhou styg, veral vir die van lae-SES kinderjare agtergrond, en dat dit onwaarskynlik is dat hierdie neigings in die nabye toekoms self sal opklaar. Dit vereis beleide om die verbruik van ongesonde voedsel te probeer verminder, en om voeding in die kinderjare te verbeter – veral in die vroegste jare van die lewe.af_ZA
dc.description.versionDoctorate
dc.format.extentxxi, 229 pages : illustrations (some color), includes annexures
dc.identifier.urihttp://hdl.handle.net/10019.1/127093
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch University
dc.rights.holderStellenbosch University
dc.subject.lcshNutrition -- South Africaen_ZA
dc.subject.lcshDiet -- South Africaen_ZA
dc.subject.lcshObesity in children -- South Africaen_ZA
dc.subject.lcshObesity -- Social aspects -- South Africaen_ZA
dc.subject.nameUCTD
dc.titleSocioeconomic status, economic insecurity and the obesity transition in South Africa : generational and life course aspectsen_ZA
dc.typeThesisen_ZA
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