The ‘nutrition transition’

Obesity is now one of the largest contributors to poor health globally, with rising rates observed over the past four to five decades.¹ Researchers have used the term ‘nutrition transition’ to describe major shifts in diet and physical activity patterns that are leading to increased rates of obesity and related chronic diseases.² Most low and middle-income countries are now moving rapidly from an ‘end of famine’ dietary pattern (as incomes have risen and nutrition improved), to a dietary pattern characterised by rising rates of obesity and nutrition-related chronic diseases. This shift has already taken place in high-income countries where it occurred more gradually.

Technology, urbanisation and the expansion of global trade have all contributed to rising obesity rates.³ In low and middle-income countries, these shifts have increased sedentary lifestyles and popularised a “Western diet,” characterised by high intake of fats (particularly vegetable oils), added sugars, animal-source foods, and refined carbohydrates. They have also paved the way for transnational food and beverage corporations to shape global and local food systems. This includes through the spread of fast-food outlets and the dominance of unhealthy foods, such as packaged snacks, confectionery and sugary drinks, as part of the food supply.

The ‘double burden’ of malnutrition

Many low and middle-income countries now face a ’double burden‘ of undernutrition (including stunting, wasting, underweight and micronutrient deficiencies) as well as overweight and obesity.¹ This double burden of malnutrition can coexist within the same country, community, and even household.⁴

The World Health Organization (WHO) recognises the double burden as the challenge of ‘malnutrition in all its forms’.⁵ In countries that have focused for decades on issues of hunger and infectious diseases, it may be difficult to get prevention of obesity and chronic disease onto the political agenda.⁴

Unhealthy food environments as a driver of unhealthy diets and obesity

The major driver of unhealthy diets and obesity are food environments that are dominated by unhealthy foods that are readily available, relatively cheap, and aggressively promoted.⁶ Accordingly, these environments have been referred to as ‘obesogenic’.⁷

Neighbourhood design also impacts health by influencing physical activity, food access, work opportunities, nature exposure, and social spaces, which in turn affect obesity and chronic disease risks.⁸ A recent systematic review and meta-analysis of 103 studies examined the association between obesity and the availability of different food outlets, such as fast-food and fresh food options.⁹ Key findings from that review, showed that, based on international evidence, proximity to food outlets which predominantly sell unhealthy food was linked to higher obesity rates, while availability of fresh fruit, vegetable supply, and supermarkets correlated with lower obesity rates. However, analyses from the Australian government do not support those international findings.⁸

Actions to address unhealthy diets and obesity at the population level

In Australia, interventions to address unhealthy diets and obesity have largely employed individual-level approaches to promote healthy choices. However, these approaches have proved insufficient, largely because they do not address the structural drivers of unhealthy diets and obesity.¹ Instead, a comprehensive approach, including government regulations, settings-based interventions and social marketing campaigns, is recommended in order to create the health promoting environments needed to address unhealthy diets and obesity at the population level.

A systems approach to obesity prevention includes a detailed understanding of key obesity drivers and their interconnections, and the design of targeted interventions at multiple levels. An example of a systems approach in the US city of Baltimore incorporated the following key components¹⁰:

• Interdisciplinary expertise: Experts from fields like civil engineering, nutrition, public health, and policy, as well as local community representatives, collaborated to develop comprehensive solutions that addressed obesity from multiple angles.
• Mapping obesity drivers: The team mapped out key causes of childhood obesity and the complex relationships among them. This provided a holistic understanding of the factors influencing obesity, such as socioeconomic status, availability of nutritious foods, and access to physical activity.
• Dynamic computer modelling: Researchers created a computer model to simulate children's daily interactions with obesity-related factors. This model incorporated variables like age, gender, weight, height, and dietary preferences to provide a realistic picture of how children encounter and respond to these factors in their day-to-day lives.
• Testing interventions: The Baltimore project used insights from the model to design and implement specific, locally tailored interventions (including cooking classes, peer mentoring, advertisements to promote healthy eating and retailer incentives for local store owners to stock and sell healthier foods).

The Global Syndemic

Obesity, undernutrition and climate change have recently been framed as a ‘global syndemic’—defined as two or more disease states that adversely interact with each other to negatively affect the trajectory of each disease.¹¹ Obesity, undernutrition and climate change share common underlying societal and political drivers that require transformative systems approaches to address them.¹ For example, obesity and climate change are both driven by the high consumption of relatively cheap energy sources (food and fossil fuels), car-oriented transportation systems, and economic systems that promote excessive and unsustainable consumption.¹ While sufficient food is produced to meet the dietary energy requirements of the global population, agricultural systems favour staple crops including rice, maize and wheat, rather than a balanced supply of fruits, vegetables, and pulses to meet recommended population-level intakes.¹²

A lack of action to address these syndemic drivers stems from inadequate political leadership and governance, strong industry opposition, and limited demand for policy action by the public.¹ This is despite the sale of energy-dense and nutrient-poor food and drinks creating a “negative externality” for which governments must bear significant obesity-related costs including healthcare, forgone revenue and reduced productivity.⁹

Transnational ultraprocessed food and beverage companies, sometimes collectively called ‘Big Food’, contribute to unhealthy dietary habits through the production and distribution of unhealthy products that are often cheap, aggressively marketed, readily available and sold in increasingly large portions. In 2018, the top 25 companies in the Big Food sector generated USD $749.30 billion in revenue and $137 billion in profit, making them hugely powerful economic entities . Former WHO Director General of the World Health Organization, Margaret Chan, has observed that “market power readily translates into political power”. Political power is then used to lobby against regulatory action such as restrictions on marketing unhealthy food to children, warning labels on unhealthy foods, or taxes on sugary drinks.