Obesity rates have reached unprecedented levels across the world, with each country’s population having its own multifaceted reason for weight problems. Worldwide, over 2.5 billion people are either overweight or obese — more than double the number of people in 1980 — and in most countries where weight problems exist, being overweight or obese is deadlier than being underweight, according to the World Health Organization (WHO).

In a 2014 study published in The Lancet, researchers found worldwide obesity rates were directly responsible for three to four million deaths. Obesity is a complex health problem resulting from a combination of behavioral and biological factors. People who are clinically obese are automatically at an increased risk for heart disease, stroke, high blood pressure, high cholesterol, type 2 diabetes, and certain types of cancer — some of which are the world’s leading causes of preventable deaths. Overloading the body with such a vast amount of excess weight labors the heart, and nearly every organ in the body, making it more difficult for a person to function through everyday life.

By far, the greatest driver of these increased rates comes from indigenous populations on Pacific islands, many of which make up the most obese countries in the world. While the United States has an increasingly obese population — pushing 33 percent — these 16 countries have staggeringly higher rates. Click "view slideshow" to learn more.