Research shows that it substantially increases the risk of a wide range of diseases, including type 2 diabetes, cardiovascular disease, and some cancers.Despite the long-established health risks, however, recent decades have seen an inexorable rise in rates of obesity throughout the world.One study found that between 1980 and 2015, the prevalence of obesity doubled in more than 70 countries and steadily increased in most others.According to the World Health Organization (WHO), in 2016, more than 650 million adults had obesity.
Overweight and obesity now claim the lives of more than 2.8 million people each year.A major challenge for researchers is to distinguish the effects of genetics from those of lifestyle on the progression of obesity.