A New study found that 30 percent of the earth's population, a staggering 2.1 billion people, is either overweight or obese.

The report showed that the highest proportion of obese people live in the United States. Obesity isn't just a problem faced by the developed world. The present study, which was based on data from 188 nations, found that weight issues are a threat to both - developed and developing countries. India and China together account for 15 percent of world's obesity.

Middle East, North Africa, Central America and Island nations in the Pacific and Caribbean also have high rates of obesity.

In the developed world, obesity rates increased from the 1980s, peaked at the start of the new millennium and then decreased since 2006. However, in developing nations, obesity rates are showing no signs of abatement.

The study was conducted by Institute for Health Metrics and Evaluation (IHME) researchers and colleagues. Obesity was defined as a Body Mass Index equal to or greater than 30 while BMI between 25 and 30 was considered overweight.

Obesity causes several health complications such as an increased risk of diabetes, heart diseases and even some types of cancer.

The study showed that obesity has increased for men (from 29 percent to 37 percent) as well as women (from 30 to 38 percent). What's worse is that obesity is now shifting to young people.

"Obesity is an issue affecting people of all ages and incomes, everywhere," said Dr. Christopher Murray, director of IHME and a co-founder of the Global Burden of Disease (GBD) study, according to a news release. "In the last three decades, not one country has achieved success 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."

Researchers found that obesity among children increased by 50 percent between 1980 and 2013. Children in Middle-East and North Africa are at a higher risk. In the developed nations, 22 percent of girls and 24 percent of boys are overweight or obese, compared to 13 percent boys and 13 percent girls in developing countries.

"The rise in obesity among children is especially troubling in so many low and middle-income countries," said Marie Ng, Assistant Professor of Global Health at IHME and the paper's lead author, according to a news release. "We know that there are severe downstream health effects from childhood obesity, including cardiovascular disease, diabetes, and many cancers. We need to be thinking now about how to turn this trend around."

The study is published in the journal The Lancet.

A recent study by the Organization for Economic Cooperation and Development had found that poor economy is fuelling obesity rates in several countries. People are cutting back on food budgets and choosing cheap, but unhealthy foods.

Processed foods are often cheap and loaded with salts and sugars. A junk food diet is linked with several health complications including obesity.