Obesity and Diet-Related Chronic Diseases
Obesity is a significant and growing public health issue that has been characterized by the World Health Organization (WHO) as a “global epidemic”.1 While obesity has been a challenge in high-income countries for some time, it is now prevalent in a growing number of lower-income countries. Approximately 1.4 billion people are overweight, of which about 500 million are obese.2 Rates of childhood obesity and overweight in particular have risen dramatically in recent decades – over 32 million overweight children are living in lower-income countries, compared to 10 million in high-income countries.3
Obesity is a major risk factor for cardiovascular diseases (e.g., heart disease and stroke), diabetes, musculoskeletal disorders and some cancers. At least 2.8 million adults are estimated to die annually due to being overweight and obese, making these the fifth leading risk for death globally.4 Obesity also has significant societal implications; in the United States alone, $190 billion in additional annual medical spending (or 21% of total U.S. medical expenditures) is attributed to obesity.5 Obesity and diet-related chronic diseases are largely preventable, but the complex systemic factors causing them present a significant challenge to developing effective solutions.
Obesity is caused by calories consumed in excess of calories expended.6 Calories consumed have increased among many people due to increased consumption of energy-dense foods, which tend to be high in fat and sugar.7 At the same time, calories expended have decreased among many people due to the increasingly sedentary lifestyle allowed by advances in technology and transportation (particularly in the context of urban environments not conducive to active lifestyles).8 No longer a problem restricted to high-income countries, similar trends are observed in lower-income countries as they undergo a “nutrition transition” driven by an increase in consumption of animal-source foods, edible oils, processed foods and sugar-sweetened drinks, as well as shifts in population from rural to urban settings.9 10 11