Are Cities Making Us Fat?

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.

Associate Professor Lim Lee Ling

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 hitting 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."

Green Spaces are a Need

Dr Ganesan Kanagasabai

Urban designs that incorporate green spaces and prioritize pedestrian- and cyclist-friendly infrastructure can help residents 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 and green spaces the general public can access easily is as important as implementing health programs such as nutrition education."

Tham Chen Munn

However,  while links between physical activity and obesity have been acknowledged in high-level urban planning documents, they are rarely emphasized or followed through in design processes at the granular level.

According to Tham Chen Munn, a Singapore-based urban planner with 25 years of experience in urban transport and infrastructure, "Micro-level urban planning tends to prioritize functionality and car movement over fostering environments that encourage walking or cycling. Without deliberate efforts and scientific thinking embedded into design practices, the potential of cities to promote healthier lifestyles remains underutilized."

Healthier Transport

The transport sector influences obesity through its impact on physical activity and access to essential services. Studies highlight disparities in the prevalence of obesity between countries with car-centric infrastructures and those with active transport systems such as the Netherlands. A Chinese study found that individuals who transitioned from bicycles to motor vehicles doubled their risk of obesity.

“Roads do not just serve as conduits for vehicles but also present psychological and physical barriers to movement. This car dependency discourages walking and cycling, creating an environment where passive transport is the default,” says Chen Munn.

"Designers and policymakers can often be reluctant to disrupt entrenched systems, and prioritize vehicle flow above pedestrian and cycling infrastructure. As a result, residents face daily structural disincentives to physical activity, reinforcing the sedentary habits that contribute to obesity," he adds.

Success stories 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. This success was made possible not only by local and state-led efforts, but also through the support of the Australian Government at the federal level.

The Australian Greenhouse Office (AGO), then a division of the Department of the Environment and Heritage, provided funding and policy backing for TravelSmart initiatives as part of national climate and sustainability strategies. This support enabled the expansion of the Perth model to other jurisdictions, including South Australia and Victoria, where local governments and communities adapted the campaign to their specific needs.

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. 

The current default in many urban food environments is the prominent promotion and placement of fast food and other less nutritious options, with longitudinal studies, such as the CARDIA study, demonstrating that proximity to fast food outlets correlates with increased consumption of unhealthy foods. Studies have also shown 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. | Photo by Dreamstime

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.

Chen Munn states, "Ultimately, reversing the trend of obesity demands empathy-driven urban design, political will, and a willingness to rethink the way we allocate and prioritize space. If cities can start to prioritize walking, cycling, and the well-being of our communities alongside vehicle flow and commercial interests, they can become not just livable, but actively health-promoting."