The term ‘nutrition transition’ describes major shifts in diet and activity leading to obesity
Many low and middle-income countries are facing a double burden of undernutrition and obesity
'Obesogenic' environments are encouraging high energy intake and sedentary behaviour
Obesity has been characterised as a systems problem with complex and interconnected causes
Obesity is now one of the largest contributors to poor health in most countries, with rates having risen steadily around the world over the past four to five decades.1 Researchers have used the term ‘nutrition transition’ to describe major shifts in diet and activity patterns that are leading to increased rates of obesity and chronic diseases.2 Most low and middle-income countries are now moving rapidly from an ‘end of famine’ pattern (as incomes have risen and nutrition improved), to a 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 expansion of global trade have helped drive the trend towards obesity.3 In low and middle-income countries these changes have led to reduced physical activity in work and leisure and a shift towards the '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.4 This includes through the spread of fast food outlets and ‘ultra-processed foods’ such as packaged snacks, confectionery and sugary drinks.
Food systems encompass the pathways by which food travels from farm to fork including growing, harvesting, processing, packaging, transporting, marketing, consuming and disposing of food. They include the various inputs (e.g. labour, technologies, materials) and outputs generated at each stage.4
are formulations of ingredients resulting from a series of industrial processes. They are based on ingredients rarely used outside these processes such as high-fructose corn syrup, modified oils and whey protein. Colours, flavours, emulsifiers and other additives are frequently added to make the final product hyper-palatable.5
As a result of this rapid nutrition transition, many low and middle-income countries are facing a 'double burden' of undernutrition (includes stunting, wasting, underweight and micronutrient deficiencies) and overweight or obesity.1 This double burden can co-exist within the same country, village, family and even individual. 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 diseases onto the political agenda.6 The World Health Organization (WHO) now recognises this as the challenge of 'malnutrition in all its forms'.7
In high-income countries such as Australia, interventions to date have largely employed individual-level approaches to promote healthy choices and prevent obesity. These approaches are insufficient without addressing 'obesogenic' modern environments that encourage high energy intake and sedentary behaviour.8 Obesogenic environments are the collective physical, economic, policy, social and cultural factors that promote obesity.8 For example, they may have a high concentration of fast food outlets and encourage driving over walking.
Obesity has been characterised as a systems problem with complex and interconnected causes, as opposed to a simple problem with linear cause-and-effect relationships. Unhealthy food marketing, for example, is driven at the societal level by economics. It can influence the physical environment (such as product placement and availability) as well as social norms, and affect individuals differently depending on individual biology and genetics.9 A systems approach is therefore needed to prevent and control obesity. An example of a systems approach in the US city of Baltimore incorporated the following key components:9
- Cultivated expertise from multiple disciplines (including civil engineering, health policy and nutrition and community representatives)
- Mapped the major causes of obesity and the relationships between them
- Created a computer model representing children’s interactions with causes of obesity (through detailed modelling of children’s movements over the course of a day broken down by gender, age, weight, height and healthy to non-healthy food preference)
- Used this model to design, implement and test interventions (including cooking classes, peer mentoring, advertisements to promote healthy eating and incentives for store owners to stock healthy foods).
The complex issues of 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).10 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 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 and fail to produce sufficient global supply of pulses, fruits and vegetables to meet recommended population-level intakes.11 Agriculture has increasingly become an engine not for producing food, but for producing biofuels and industrial ingredients for processed food products (e.g. sugar-sweetened beverages, ready-to-eat meals and snacks).11
A lack of action to address these syndemic drivers is due to 'policy inertia': a collective term for inadequate political leadership and governance; strong opposition by powerful commercial interests to policies in the public good; and a lack of demand for policy action by the public.1 This is despite the sale of energy-dense and nutrient-poor food and drink creating a 'negative externality' for which governments must bear significant obesity-related costs including healthcare, forgone revenue and reduced productivity.
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.12 In 2018, the top 25 companies in the sector generated USD $749.30 billion in revenue and $137 billion in profit, making them hugely powerful economic entities.13 Former Director General of the World Health Organization, Margaret Chan, has observed that 'market power readily translates into political power'.14 Political power is then used to lobby against regulatory action such as bans on marketing unhealthy food to children, warning labels on unhealthy foods or taxes on sugary drinks.