A new study, conducted by researchers at the Institute for Health Metrics and Evaluation at the University of Washington, highlights obesity as a major public health epidemic in the developed as well as the developing parts of the world.

Based on the analysis of data from 188 countries during 1980-2013, the researchers found that nearly 30 percent or 2.1 billion people of the world's population are either obese or overweight.

Overweight is defined as having a Body Mass Index (BMI) greater than or equal to 25 and lower than 30, while obesity is defined as having a BMI equal to or greater than 30.

The study also found that overweight and obesity rate has increased from 29 to 37 percent in adult men and from 30 to 38 percent in adult women. Developed countries showed higher number of overweight and obese men, while women in developing countries were associated with increased risk of becoming overweight or obese.

"Obesity is an issue affecting people of all ages and incomes, everywhere," said Dr. Christopher Murray, director of IHME, in a statement. "In the last three decades, not one country has succeeded in reducing obesity rates, and we expect obesity to rise steadily as incomes rise in low- and middle-income countries in particular, unless urgent steps are taken to address this public health crisis."

The study titled, "Global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013: a systematic analysis for the Global Burden of Disease Study 2013," is published in The Lancet.