Are our cities making us fat? The curse of the modern obesogenic environment in Southeast Asia
The global prevalence of obesity has tripled since the 1970s, affecting populations in high- and low-and middle-income countries; with Southeast Asia being particularly heavily affected. Despite extensive efforts in primary prevention, obesity rates continue to climb.
Current strategies often focus on individual behaviors such as diet and physical activity. However, growing evidence underscores environmental factors which inhibit healthy behaviors and foster conditions such as diabetes, which contribute to weight gain and obesity. Environments that encourage obesity are also known as obesogenic environments.
According to Associate Professor Lim Lee Ling, Associate Professor of Medicine and Head of the Diabetes Care Unit, Universiti Malaya Medical Centre, Kuala Lumpur, Malaysia, “More individuals are being diagnosed with diabetes, particularly in regions experiencing rapid economic development where stress levels are increasing due to fast-paced urban living.”
Malaysia has the highest rate of obesity in Southeast Asia, with its current obesity rate among adults reaching 54.4% according to the National Health and Morbidity Survey 2023.
The COVID-19 complication
More recent developments such as the COVID-19 pandemic could trigger the onset of diabetes in some individuals and exacerbate existing metabolic conditions which result in both Type 1 and Type 2 diabetes. The virus has been shown to impact the pancreas, which is responsible for insulin production, potentially leading to new cases of diabetes, particularly among the prediabetic group.
Associate Professor Lim elaborates, "Lockdowns, restricted movement, and economic hardships during the pandemic also caused many people to adopt more sedentary behaviors and consume unhealthy diets, both of which lead to obesity. Patients with high blood glucose levels, a condition known as hyperglycemia, have been shown to experience worse outcomes compared to those without glucose abnormalities, even up to six months post-COVID, with longer hospital stays, more severe symptoms, increased need for oxygen and ventilation, and more intensive care treatments."
Additionally, those who suffer from long COVID, with symptoms persisting for three months or more after they have recovered from the initial infection, may experience persistent metabolic changes that increase their risk for diabetes. For example, chronic inflammation and immune dysregulation caused by long COVID may affect blood glucose regulation, further contributing to the development of diabetes and obesity.
Green Spaces are a Need
Studies reveal that individuals living in areas with more green spaces report better health outcomes and lower prevalence rates of chronic diseases, including obesity. Yet most of Southeast Asia’s capital cities are notorious for their lack of green spaces, even the Garden City of Singapore.
Urban designs emphasizing walkability, with mixed land use and pedestrian-friendly infrastructure, facilitate physical activities such as walking and cycling to schools, offices and other amenities, helping reduce or slow weight gain over time.
Additionally, green environments alleviate stress and mental fatigue, which are associated with weight gain. Enhancing green areas and ensuring accessibility can also reduce air pollution, which can contribute to obesity through mechanisms such as inflammation and oxidative stress.
Dr Ganesalingam Kanagasabai, Consultant Gastroenterologist at the Subang Jaya Medical Center states, "To create a healthier environment for the population, building and maintaining exercise facilities the general public can access easily is as important as implementing health programs such as nutrition education, and disseminating evidence-based information on social media."
Healthier Transport
The transport sector influences obesity through its impact on physical activity and access to essential services. While transport methods such as walking and cycling are associated with healthier weight outcomes, the climate and traffic pollution levels in many Southeast Asian cities dissuade many from making these choices. Many urban areas are designed to favor cars over pedestrians and cyclists, putting additional barriers in the way of active transport options.
Studies highlight disparities in prevalence of obesity between countries with car-centric infrastructures and those with active transport systems such as the Netherlands. For instance, a Chinese study found that individuals who transitioned from bicycles to motor vehicles doubled their risk of obesity.
Retrofitting urban environments to promote active transport — through pedestrian-friendly designs, cycling paths, and robust public transit systems — can significantly increase population-level physical activity. Initiatives such as Perth’s TravelSMART campaign in Australia, which encouraged active transport via marketing, resulted in a 14% reduction in car use and sustained increases in walking and cycling.
The Issue with Light
Our 24-hour cities and their Artificial Light at Night (ALAN) have emerged as a novel risk factor for obesity. Exposure to ALAN disrupts circadian rhythms and suppresses melatonin production, which regulates metabolic processes. Epidemiological studies reveal a positive correlation between ALAN exposure and obesity rates. For instance, a large cohort study found that individuals exposed to higher levels of outdoor ALAN had significantly greater odds of developing obesity over a decade.
Mitigating light pollution through policies regulating urban lighting and promoting natural light exposure during the day could reduce circadian disruption. Such measures would complement broader efforts to create health-supportive environments.
How the Environment Shapes Dietary Habits
Although what we eat is usually considered a lifestyle choice, research suggests that both the type and amount of food and drink we consume are influenced by environmental cues, to a surprisingly large extent.
Longitudinal studies, such as the CARDIA study, demonstrate that proximity to fast food outlets correlates with increased consumption of unhealthy foods. Other studies show that areas with increased access to fast food outlets and convenience stores offering processed food with high sugar and fat content have a higher prevalence of obesity.
To mitigate this issue, policies aimed at reducing the density of fast food restaurants and/ or improving their offerings and curbing the aggressive and flashy advertising of fast food should be implemented.
The timing of food consumption significantly impacts metabolism and weight regulation. Late-night eating disrupts circadian rhythms, promoting fat storage and weight gain. Controlled studies on humans and rodents confirm that eating during biologically inappropriate times leads to greater weight gain despite similar caloric intakes. Policies encouraging earlier mealtimes in restaurants and public awareness campaigns on meal timing could improve metabolic health.
Economic development and globalization have been driving the increase in consumption of ultra-processed foods (UPFs), even in Southeast Asia. UPFs, which are characterized by high calorie density and low nutritional value, contribute to obesity in a substantial way. Addressing this trend requires systemic changes, such as implementing regulations that limit advertising and marketing of UPFs, and incentivizing the production and consumption of minimally processed, nutrient-rich foods.
Menu labeling and the introduction of healthier meal options in hawker centers and fast food outlets, such as the lower fat and sodium options introduced in several Southeast Asian countries have shown promise. A meta-analysis of 15 studies revealed that menu labeling reduced energy intake by approximately 100 kcal per meal. However, it is not enough to merely list caloric values; nutrient-dense meals must also be promoted in appealing ways. Training chefs to specialize in preparing balanced and nutritious meals could transform restaurant offerings and align dining habits with health goals.
Conclusion
We might not be able to rebuild our cities, but we do need to rethink them if we are to change our eating habits. Obesogenic environments are central drivers of the obesity epidemic. Addressing this crisis requires a paradigm shift that integrates environmental, policy, and community-level interventions. By prioritizing green spaces, active transport, nutritious food, and lighting aligned to circadian rhythms, we can foster environments conducive to healthy behaviors.
Collaborative efforts across non-health sectors—including urban planning, transportation, and food industries—are essential for sustainable progress. Modest yet widespread environmental changes have the potential to reverse obesity trends and improve population health.
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