In 1980, there were 857 million overweight and obese people on the planet. Today that number is 2.1 billion, which means that nearly 30 percent of the worlds population is obese or overweight, concludes a study published in The Lancet yesterday. And whats more worrisome is that no nation has managed to significantly decrease its obesity rates in the last 33 years. In the study, researchers at Washington University used data from 188 countries collected between 1980 and 2013 to determine how the prevalence of overweight and obese people has changed over time.