Discussion

Our study showed 14% older Indians had EW, while underweight was 2.5 times more prevalent. However, more than one of three older Indians possessed CA; and CA is considered an equally if not more important independent risk factor of cardiometabolic diseases.22 This indicates that accumulation of additional weight in later life among Indians was yet to assume substantial proportions compared to their undernutrition-related lack of appropriate body mass, albeit currently, the problem of abdominal fat accumulation manifested as CA was definitely not negligible among these older adults. This was even more significant because a sizeable proportion of these CA-affected older Indians had normal BMI, indicating abdominal girth being a more sensitive guide than weight-based metric, to measure obesity-related risk among older Indians.

What also becomes more significant from the public policy perspective is that not only one out of two older Indians in the top 30% wealth bracket has CA, but also, one of four among the less wealthy 70% possesses it. Even more remarkable is the distribution among older Indian women, every second of whom is affected with CA, and where the wealth gradient for CA is narrower; 69% among the wealthier 30% and 46% in the less wealthy 70% of older women have CA.

Hence, perhaps for the first time, our study, from a nationally-representative sample of older Indians, illustrated that although a distinct positive economic gradient exists, obesity, especially the abdominal variety, is definitely no longer only restricted to affluent older Indians. The ‘poorer 75%’ are also substantially affected, large sections of whom are believed to be still surviving on an average of US$2 per day.32

Every 17th Indian aged 50 years or over suffered from CA-related hypertension, a fraction of which could be perhaps apportioned to their high BMI; but after accounting for BMI, 1 of 22 had prevalent hypertension exclusively attributable to CA. In the lower 70% wealth bracket, the BMI-adjusted and BMI-unadjusted portions of hypertension attributable to CA were of comparable magnitude. It must be considered that these benefits were estimated in terms of only one obesity-related outcome, hypertension, whereas far greater benefits may be achieved in terms of other obesity-driven conditions such as diabetes, cardiovascular disease and musculoskeletal disorders, which could not be evaluated here due to lack of their objective measures in the SAGE sample. This indicated that prevention and control of CA, which will also largely mitigate the EW problem, will benefit many older Indians across all socioeconomic strata.

Subramanian et al33 apprehended that any significant resource allocation to the control of non-communicable diseases in the current Indian context would deprive the poor, causing diversion of scant public health resources from control of infectious and childbirth-related diseases, which affect the vast majority of Indians, who are predominantly poor. They concluded that the burden of chronic ailments and their risk factors is significant among the poor but> largely restricted to the minority elite in India. Opponents argued12–15 that there are signs of ‘reversal’ of this positive socioeconomic gradient for chronic age-related diseases, claiming the poor are now more affected by them; hence their demand for significant public investment into non-communicable diseases.12 Our study, reflecting the national situation among older Indians as opposed to regional or predominantly urban results, suggests a cautious middle ground14 in this ‘problematic discourse.33 Although a positive socioeconomic gradient for obesity was strongly evident among the current country-wide older population, the significant prevalence of CA, even among the older underprivileged and, especially, women, cannot be ignored. This certainly calls for a prompt population-based policy response against obesity, especially with an eye towards its older population, which may enable them to lead a relatively morbidity-free and disability-free productive later life. Otherwise, delay in action can make the obesity problem too deeply entrenched and resource intensive to uproot, and, even worse, starts inequitably affecting the lower socioeconomic sections more, as has happened in many developed nations, the so-called ‘reversal’ of their socioeconomic gradient.4 However, all efforts should be made to preserve public investment for the ‘unfinished business’ of undernutrition and poverty-related diseases, which still affects a large section of the population, especially when they are young and in their reproductive ages.

From the crude and independent effects of various social determinants, and using a priori knowledge, we drew a causal link among social determinants leading to CA34 (figure 2). Calorie overconsumption and calorie underexpenditure were included in the causal diagram as the most proximate factors leading to CA, though these lifestyle characteristics were not objectively measured in the sample. The hypothesised causal links were empirically validated post hoc using Bayesian Network Learning (‘bnlearn’ package in R).35 The empirical results almost matched the a priori assumptions, however, the arc between caste and education was missing in the Bayesian Network (see online supplementary figure S1).

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Figure 2

The association between obesity and its various social determinants. The solid arrows denote causal relationship; the lines without arrows denote association; the dotted arrows denote suggested protective pathways which should be utilised as a preventative antiobesity strategy.

Our result describes wealth as the major driver of obesity having largest standardised coefficients in the fully adjusted model. Wealth-driven overconsumption has flourished within the culture of chronic food deprivation that Indian society had experienced for centuries; hence any form of socioeconomic advantage was utilised for accumulating extra calories. Also, socioeconomic prosperity was perhaps related to increased sedentariness. Privileged occupation and caste, major sources of inequity in Indian society, were positively associated with obesity, largely through increased wealth and sedentariness. Association between urban living and obesity was partly explained by clustering of obesogenic factors such as wealth, education and white-collared occupation in the cities, and partly mediated by the direct effect of a less active urban lifestyle with regard to commuting and daily chores.

Despite its effect attenuating substantially after adjustment for wealth and occupation, through which it is believed to affect obesity, educational achievement was yet to caste any direct protective antiobesity effect among older Indians, unlike in many middle and high-income countries,4 where cognitive and information processing skills acquired from education are believed to help their citizens to negotiate the wealth-related overconsumption and underexpenditure of calories, marking the gradient ‘reversal’ in those societies.

Despite the entrenched, or also perhaps growing, wealth inequity in Indian society,36 a large number of underprivileged Indians—the ‘lower 75%’33—have undeniably benefitted from the post-nineties’ economic growth; and, furthermore, the current economic environment of India will continue to increase the prosperity of many more Indians across all socioeconomic strata. Simultaneously, both calorie overconsumption and underexpenditure are likely to become more affordable and achievable to everyone through greater availability of calorie-dense industrially produced food at relatively cheaper prices, notwithstanding food inflation in the country; increasing automation of jobs and domestic chores even in the low-earning segment; and increased rate of urbanisation. This will accelerate the obesity burden in all strata of Indian society, though the ‘reversal’ of the positive socioeconomic gradient in the recent foreseeable future seems unlikely; this will only happen when the country crosses a certain economic developmental threshold,4 ,5 enabling the protective effect of education to ‘kick in’.

From the policy perspective, this growing obesity problem, affecting all societal strata, has to be confronted through investment in population-based public health initiatives, among which large-scale promotion for adoption, at all stages of life, of appropriate lifestyle, a component that is prominently missing from the current rudimentary Indian national programme for non-communicable diseases, should be prioritised.37 The societal aspiration for ‘big size’ and ‘sedentariness’ as signs of accomplishment38 may also have to be counteracted. Legislation against the food industry or development of active lifestyle-enabling urban infrastructure may follow. However, the first and foremost step would be to put obesity into the centre stage of the national sociopolitical discourse, so that Indians recognise it as a serious problem, as has been done recently with similar ‘big ticket’ societal issues in India, such as sanitation and toilet use.

In terms of future policy and research implications, targeted emphasis must be laid on Indian women, as they have substantially greater independent risk of obesity, which renders them more vulnerable to its dire health outcomes, especially disability,39 which may hinder their independent community living in later life.

Our study's limitation is its cross-sectional design, perhaps partly compromising our causal inferences. However, the described causal relations are so plausible that such bias, if any, is perhaps negligible. Also, among older Indians, the role of age-related frailty inflating the underweight segment and obscuring some of the obesity-social determinant relationship, cannot be entirely ruled out. Detailed and objective measures of dietary habits including salt consumption and physical activity were not collected in the SAGE sample; these measures could have provided us with an opportunity to explore the role of these mediators in the pathway to excess weight, obesity and hypertension in this population.

The strength of our study is the India-wide generalisability, precise estimates and reliable measures40 from the large nationally representative SAGE sample; also emulating ELSA, SHARE and HRS designs, which helped to generate valuable chronic disease-related evidence with policy implications for the older population in those countries.

To conclude, our study has shown, for the first time, to the best of our knowledge, that obesity, mainly the abdominal variety, has a country-wide presence of significant proportion in the Indian population of individuals aged 50 years and older; and although the richer are more affected, the problem is also substantial in the lower socioeconomic stratum. Wealth being its strongest social driver and with ongoing economic growth of India, obesity is likely to increase rapidly in all the socioeconomic segments, unless acted on promptly, which should entail putting obesity into the national sociopolitical discourse and combating it through primordial population-based preventative actions.