Excess calorie consumption and physical inactivity are often cited as the main drivers of obesity, diabetes and heart disease. Yet, these lifestyle factors may explain only part of South Asia’s growing cardiometabolic crisis. An overlooked contributor is environmental exposure, particularly air pollution.

Fine particulate matter (PM2.5) may contribute significantly to the region’s growing burden of diabetes and cardiovascular disease, according to a new paper in The Lancet Regional Health – Southeast Asia. The paper examines how a combination of environmental exposures, including air pollution, endocrine-disrupting chemicals, ultra-processed diets, disrupted sleep and climate-related stress, may affect cardiometabolic health. The authors use the term “exposome” to describe the totality of environmental exposures a person encounters throughout their lifetime.

Titled “South Asia’s cardiometabolic burden: exposomal determinants of a health transition”, the paper is authored by Yashendra Sethi of the Department of Medicine at Subharti Medical College, Swami Vivekanand Subharti University, Meerut, and Dr Anoop Misra, endocrinologist and chairman of Fortis C-DOC, New Delhi. The authors call for a broader understanding of metabolic health that considers environmental conditions alongside conventional lifestyle factors.

“Excess calorie intake and physical inactivity alone cannot explain this epidemic. We must move past conventional lifestyle-centred thinking to recognise the modern exposome, the cumulative burden of environmental exposures interacting with South Asians’ unique metabolic susceptibility. Major drivers include air pollution (PM2.5), endocrine-disrupting chemicals, circadian disruption, ultra-processed diets, and climate-related stress,” says Dr Misra.

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How pollution may affect metabolic health

Chronic exposure to PM2.5, which frequently exceeds World Health Organization (WHO) guideline levels across South Asia, has been associated with cardiovascular and respiratory diseases, as well as biological processes linked to metabolic dysfunction. These include insulin resistance, oxidative stress, mitochondrial dysfunction, endothelial damage affecting the inner lining of blood vessels, and changes in fat-cell function.

The authors also identify endocrine-disrupting chemicals, including bisphenols, phthalates and per- and polyfluoroalkyl substances (PFAS), as potential contributors. These substances can interfere with hormone signalling, fat-cell development, appetite regulation and insulin sensitivity. They are used in a range of industrial and consumer products.

Other factors may compound these effects. Sleep deprivation, shift work, irregular eating patterns and circadian disruption can affect metabolic regulation. Ultra-processed diets and psychosocial stress may add to the burden, while environmental and dietary exposures may also influence the gut microbiome and the body’s inflammatory response.

Together, these interacting exposures may contribute to chronic low-grade inflammation, dysfunctional fat tissue and vascular injury. The authors suggest that such factors could help explain the earlier onset of type 2 diabetes, metabolic dysfunction-associated steatotic liver disease and atherosclerotic cardiovascular disease.

Why South Asians may be particularly vulnerable

South Asians tend to develop cardiometabolic diseases at younger ages and at lower body mass index (BMI) levels than many Western populations.

The authors argue that this vulnerability must be considered alongside the region’s rapid transformation over a single generation. Historical undernutrition and famine were followed by rapid urbanisation, mechanisation and significant dietary changes. Biological adaptations that once favoured energy storage and fat accumulation may now interact with modern environmental exposures.

The regional burden is substantial. The paper cites estimates showing that the burden of cardiometabolic disease, measured in disability-adjusted life years, increased 1.7-fold to 3.7-fold across the Asia-Pacific region between 1990 and 2023.

Changes in the exposome may help explain this worsening burden, the authors suggest. However, further research is needed to establish how individual exposures, and their interactions, contribute to disease among South Asian populations.

‘Prevention must go beyond lifestyle advice’

“Individuals may reduce their risk of diabetes and cardiovascular disease through healthy eating, regular exercise, and proper sleep. However, the causes of these diseases now reach far beyond individual control. Air pollution, endocrine-disrupting chemicals, climate stress, rapid urbanisation, and unhealthy food environments increasingly influence metabolic health,” explains Dr Misra.

“Prevention must therefore go beyond lifestyle advice. It needs concerted, multisectoral efforts engaging governments, environmental agencies, food regulators, and medical systems. Individual responsibility must now be matched by collective and governmental responsibility,” he adds.

The authors outline four priorities: systematically monitoring environmental, food, sleep and climate exposures; introducing interventions from prenatal life and early childhood; adopting environmental and food-system policies that complement individual lifestyle changes; and conducting long-term research linking exposures to cardiometabolic outcomes.

The approach does not diminish the importance of a healthy diet, regular exercise or adequate sleep. Instead, it highlights how the conditions in which people live, work and eat can shape their health risks and the choices available to them.