A groundbreaking global study has upended long-held beliefs about the true drivers of the obesity epidemic, finding that overeating—particularly of ultra-processed foods—is about ten times more responsible for rising obesity rates than a lack of exercise. This revelation carries profound implications for Thailand, where rates of overweight and obesity are increasing alongside rapid urbanisation and changing dietary patterns.
For decades, both Thai and international health authorities have emphasised the importance of physical activity in tackling obesity, broadcast through nationwide campaigns and initiatives. The popular narrative has been that sedentary lifestyles, especially in urban areas like Bangkok or Chiang Mai, are to blame for waistlines expanding. Yet, new research published in the Proceedings of the National Academy of Sciences (PNAS) suggests this perspective may miss the mark. Based on an analysis of over 4,000 adults from 34 nations—including hunter-gatherer tribes in Tanzania, herder-farmers in Siberia, and executives in Norway—researchers found that people across cultural and economic backgrounds actually burn roughly the same amount of calories per day, regardless of whether their lives are active or sedentary (Washington Post).
Central to the study’s methodology is the use of doubly labeled water, a gold-standard tool for determining energy expenditure over time. This allowed researchers to measure precisely how many calories participants burned in daily life, accounting for both biological operations and physical activity. After carefully adjusting for body size—which can skew absolute calorie burn figures—it became clear that even the most active communities did not significantly outpace their western counterparts in energy expenditure. According to the lead author, a professor of evolutionary anthropology and global health at Duke University, “Our analyses suggest that increased energy intake has been roughly 10 times more important than declining total energy expenditure in driving the modern obesity crisis.” In short, obesity’s primary engine is eating too much, not moving too little.
This nuanced finding demands a shift in perspective and policy, not just for Western countries but for rapidly modernising nations like Thailand, where lifestyle diseases are rising as economic prosperity grows. The allure of fast food, sugary drinks, and convenient snacks—often ultra-processed and energy-dense—has transformed the Thai diet as it has elsewhere. While traditional foods like khao tom or tom yam are still common, the influence of convenience stores and global fast-food franchises has increased sharply, especially in urban centres.
The study’s findings are reinforced by a deeper analysis of diet composition. Researchers observed a strong positive correlation between the percentage of daily diets made up of ultra-processed foods—defined as industrial formulations containing five or more ingredients—and higher body-fat percentages across different populations. This aligns with observations in Thailand, where food environments saturated with cheap, processed snacks, sweetened beverages, and buffet promotions have become the norm. According to a professor at the Gillings School of Global Public Health at the University of North Carolina, “This study confirms what I’ve been saying, which is that diet is the key culprit in our current [obesity] epidemic.” Similar sentiments come from leading experts at Tufts University in Boston, who note, “It’s clear from this important new research and other studies that changes to our food, not our activity, are the dominant drivers of obesity.”
Yet, while the study downplays the role of inactivity in causing obesity, it does not diminish the health benefits of regular exercise. The Duke University professor emphasises, “We know that exercise is essential for health. This study doesn’t change that.” Evidence continues to support the positive impact of physical movement on mental health, cardiovascular risk, blood sugar management, and community well-being. In Thailand, social activities like group aerobics in city parks, morning runs along rivers, or traditional dance classes remain important pillars of health promotion. Nevertheless, the implication is clear: efforts to curb obesity must prioritise dietary change over simply prescribing more exercise.
For Thai policymakers, public health leaders, and educators, these findings suggest a pressing need to redirect national attention from “move more” slogans to comprehensive strategies targeting food environments, marketing, and affordability of healthy options. Recent data from the Thai National Health Examination Survey show a continuous uptick in overweight and obesity rates, especially among young people and adults in cities (Thai Health Promotion Foundation). The popular emergence of obesity-related diseases, such as type 2 diabetes, hypertension, and certain cancers, underscores the urgency of effective intervention.
Thailand is already grappling with many of the dietary changes that fuel the current obesity crisis. In urban grocery stores and convenience chains, ultra-processed snacks and instant foods occupy prominent shelf space. Research published in the Asia Pacific Journal of Clinical Nutrition has previously linked the increased consumption of processed foods and sugary beverages to body weight gain among Thai schoolchildren (Asia Pacific J Clin Nutr). School canteens and vending machines stocked with sweetened drinks and high-calorie snacks present a daily temptation for students. Meanwhile, the economic growth and time pressures of modern life have made fast, convenient food options more attractive to busy families.
Public health responses in Thailand have typically involved campaigns promoting regular exercise, with less emphasis on the critical role of diet. School-based interventions frequently include physical activity goals, but evidence from this new study suggests a stronger focus on nutritional literacy, healthy meal planning, and regulation of food marketing is urgently needed. For instance, fiscal policies such as taxing sugar-sweetened beverages—already in place in Thailand but often circumvented by new beverage formulations—or mandatory front-of-pack warning labels for high-sugar or high-fat foods, could be further strengthened. International examples, such as Chile’s bold approach to food labelling and advertising, offer concrete policy templates to consider (The Lancet).
This study also invites reflection on Thai society’s historical and cultural relationships with food and body image. In the past, “well-rounded” body types were sometimes viewed as a sign of prosperity and health. However, shifting social norms, media influences, and the spread of Western beauty ideals have complicated these perceptions—sometimes increasing stigma around obesity without tackling the root causes. Still, it is important to acknowledge that traditions of communal eating, vibrant fresh markets, and locally sourced ingredients remain strong in many regions, offering counterweights to processed food culture.
A significant challenge lies in the fact that ultra-processed foods are not just convenient—they are designed to be hyper-palatable and often cost less than healthier options, particularly for low-income families. Thai policymakers may need to intensify efforts to make fruits, vegetables, and minimally processed staples both affordable and accessible. Nutritional education, starting from young ages, is equally vital. Teachers, health professionals, and community leaders can utilise digital tools and social media to spread evidence-based dietary advice tailored to Thai tastes and lifestyles.
Looking ahead, the projected growth of Thailand’s urban middle class and the continued proliferation of foreign and domestic processed food brands suggest the obesity problem may worsen without decisive action. Simultaneously, advancements in technology and public health offer hope: digital food tracking, government incentives for healthy eating, urban farming initiatives, and creative media campaigns can play a role in shifting behaviours.
Ultimately, the new global research compels a bold rethinking of obesity prevention in Thailand and elsewhere. Rather than treating physical inactivity as the chief villain, policymakers must focus on creating food environments where healthy choices are easy, affordable, and desirable. This may involve reforming agricultural subsidies, regulating food advertising (especially to children), and empowering consumers with the knowledge to favour fresh, minimally processed foods.
For Thai readers, the call to action is clear: rethink not just how much we move, but what we eat. At home, prioritise meals made from fresh vegetables, lean proteins, herbs, and rice over processed, packaged snacks and sugary drinks. Advocate for healthier food options in schools, workplaces, and communities. Support local markets and food producers that celebrate traditional, nutritious Thai cuisine. And continue engaging in regular physical activity—not primarily for weight loss, but for holistic health and social well-being. By focusing on what goes onto the plate, not just the number of steps taken, Thais can protect themselves and future generations from the growing burden of obesity.
Sources: Washington Post, Thai Health Promotion Foundation, Asia Pacific J Clin Nutr, The Lancet