Obesity is no longer a problem confined to developed countries and higher-income populations. The spread of obesity and overweight has increased everywhere, including in low-income countries. Today, at the global level, almost half of all countries are grappling with both undernutrition and overweight and obesity. Indeed, malnutrition and obesity often coexist in the same community, and sometimes even within the same household.

Economic and social transformations in many low- and middle-income nations, combined with the relatively low-cost availability of highly processed ready-made foods, have led to changes in lifestyles and dietary habits across the world, alongside a reduction in physical activity.

Obesity is growing everywhere

Not a single country — not one — saw a decline in obesity between 2000 and 2013. The World Health Organization estimates that 1.9 billion people are overweight, and of these a third are obese. This entails enormous social and economic costs which, added to those stemming from malnutrition, society cannot afford to sustain.

The 2013 edition of the Fao report The State of Food and Agriculture found that the social burden caused by overweight and obesity has doubled over the past two decades. According to the report, the cumulative cost of all non-communicable diseases for which overweight and obesity are the main risk factors amounted to approximately 1,400 billion dollars in 2010.

More recently, the McKinsey Global Institute estimated that the global cost of obesity — including the increased risk of heart disease, hypertension, stroke, diabetes and certain types of cancer that affect overall quality of life — could reach 2,000 billion dollars a year, third only to smoking (2,100 billion dollars) and armed conflict (2,100 billion dollars). While the figures are not directly comparable and global estimates of the economic costs of obesity and overweight vary, they all converge on the overall scale of the phenomenon.

Consider what could be done to tackle malnutrition — hunger, undernutrition, micronutrient deficiencies and obesity — if we had not squandered those vast sums of money. Greater funding is needed to increase commitment, but this should form part of a broader effort to launch new strategies and address malnutrition in all its forms, seeking to go beyond the immediate causes and encompass its wider dimensions — socio-cultural, economic and political.

This was one of the challenges discussed at the second International Conference on Nutrition (Icn2), held in Rome in November 2014. At the conference, governments approved the Rome Declaration on Nutrition and its accompanying Framework for Action, committing to address malnutrition in all its forms — undernutrition, stunting, wasting, micronutrient deficiencies, obesity and related diseases.

Making progress on this commitment will require significant changes in the way malnutrition is addressed. It involves shifting from treating the negative effects of malnutrition to preventing them by ensuring a healthy and balanced diet, better tackling its root causes, and developing new policies, strategies and programmes.

Some guidelines

First and foremost, our food systems must be reformed to ensure better nutrition for all. The State of Food and Agriculture 2013 report showed how food systems influence the quantity, quality, diversity and nutritional content of foods, and determine the availability, accessibility and affordability of foods needed for good nutrition. Reforming our food systems to improve nutrition will require more nutrient-rich foods and a guarantee of sound food processing to minimise the loss of nutrients.

Secondly, it is necessary to make it easier for consumers to make food choices that promote healthy diets. This requires political commitment, as well as effective and coherent programmes and strategies. It will call for greater investment in nutrition promotion and educational programmes. Schools, workplaces and communities should be encouraged to provide easily accessible healthy diets, and people should be urged to take more physical exercise. It will require equipping consumers with information through popular nutrition education — both formal and informal — and by providing more information about the food being sold, including through adequate and accurate labelling.

Thirdly, it is necessary to create a shared vision and a multisectoral approach involving governments, the agricultural sector, health, retailers and other key public and private sectors, as well as civil society. The multiple causes of malnutrition, including obesity, demand effective collaboration: no single sector or body can solve the problem alone.

Fourthly, trade and investment agreements must be designed to exert a positive influence on food systems. By improving food availability and access, efficient and effective trade can play an important role in achieving nutrition objectives. However, such agreements should not "crowd out" the possibility of developing local agriculture. Thriving and well-functioning national and local agricultural systems not only reduce countries' dependence on food imports, but also promote greater diversity in diets, act as a buffer against price spikes on international markets, and generate employment that helps reduce rural poverty.

The second International Conference on Nutrition laid the groundwork for all parties involved to commit to reversing the rapid rise in global obesity. Malnutrition, from undernutrition to obesity, is preventable at a relatively low cost if one works efficiently and in a coordinated manner. Swift action is needed to reverse obesity trends and to consign hunger and all forms of malnutrition to the past.