Obesity is one of the most prevalent health problems of the 21st century. Global levels of obesity have nearly tripled since 1975. According to 2016 data from the World Health Organization, more than 1.9 billion adults, ranging between 18 years and older, are overweight. Of these, over 650 million are obese (defined as a body mass index >30 kg/m2). The Centers for Disease Control reported in February 2020 that the prevalence of obesity in US adults increased from 30.5% to 42.4% and the prevalence of severe obesity increased from 4.7% to 9.2% in less than a 20-year period (from 1999–2000 through 2017–2018).