Obesity: A Long-Term Global Challenge

Obesity involves excessive accumulation of body fat. While largely preventable, it has become increasingly common in most of the world in recent decades. Obesity can cause severe health problems, including cardiovascular diseases, musculoskeletal disorders, respiratory conditions, and type 2 diabetes mellitus. It also leads to negative psychological outcomes such as depression and low self-esteem, as well as discrimination and stigma. Recently, the long-term obesity epidemic has interacted with the sudden onset of the COVID-19 pandemic, during which patients with obesity have experienced higher rates of hospitalisation, ICU admission and death. The increases in obesity prevalence have been caused by changes in diet, with greater availability of energy-dense foods, and reductions in physical activity. These developments have been influenced by factors such as socio-economic status. In this chapter, we describe the long-term global challenge posed by obesity. We provide an overview of patterns across the world, but focus particularly on trends in nine countries. China and India are of key importance because of their large populations; they are experiencing diverging trends in obesity in children that will have major consequences over the lifecourse. Other countries have had particular experiences of obesity, including the early-onset and severe epidemics in Nauru and the USA, and the relatively benign trends in Japan. Trends in Brazil, Germany, Iran and South Africa are also described in detail, because they are large countries that are representative of their wider regions. Finally, we suggest ways in which obesity and its determinants should be monitored in coming decades, to maximise the impact of interventions for tackling this complex global challenge