The United States still retains the dubious distinction of being the heaviest country in the world.
But obesity is a growing problem for many other nations as well.
“Since 1975, the prevalence of obesity worldwide has nearly tripled,” said Kenneth Thorpe, PhD, chairman for the Partnership to Fight Chronic Disease, and professor of health policy and management at Emory University in Georgia.
“It’s also the leading cause of preventable mortality,” he added, “because obesity leads to diabetes, cardiovascular disease, stroke, and other diseases.”
This trend is a big shift from 20 years ago, when undernutrition in developing countries was a main concern for aid organizations.
But now, most of the world’s population lives in countries where obesity and being overweight kill more people than being underweight, according to the World Health Organization.
The rise in obesity is particularly problematic among children and teens.
A new study published on October 10 in The Lancet found that the number of obese children and adolescents was 10 times higher in 2016 than in 1975 — 124 million compared to 11 million.
The Cook Islands, Nauru, and other Pacific islands had the highest obesity rates in 2016 — more than 30 percent of their young people are obese.
The next highest obesity rates among youth were among the United States, some Caribbean countries, and the Middle East — with more than 20 percent of youths aged 5 to 19, obese.
In the United States, the obesity epidemic shows no sign of slowing, reported the National Center for Health Statistics — in spite of government efforts to contain it.
In 2016, nearly 40 percent of American adults and 19 percent of young people were obese, according to the report.
Adult obesity in the United States has also risen 30 percent since 1999. Youth obesity rose 33 percent during that time.
Complex factors behind obesity
The simple explanation for the global rise in obesity is that people are eating more high-calorie, high-fat foods and are less physically active.
Highly processed foods — with added sugar, salt, and artificial ingredients — are often cheaper, easier to ship, and have a longer shelf life than fresh foods.
As a result, these foods have started to replace traditional diets based on whole foods — even in countries that once struggled to feed their population.
“In some lower-income countries and certain populations, it’s easier for people to get processed foods, as opposed to fruits and vegetables,” Dr. Bruce Lee, executive director of the Johns Hopkins Global Obesity Prevention Center, told Healthline.
But the rise in obesity isn’t just replacing undernutrition. These can coexist in the same country, neighborhood, and even household.
“There is this paradoxical situation developing, where you have a combination of both undernutrition and elevated bodyweight,” said Lee.
The authors of The Lancet study estimated that 192 million young people were moderately or severely underweight in 2016.
On average, people are also much less active than they used to be. This shift has occurred alongside increased urbanization and changes in the built environment.
“Your environment really helps govern what you do each day,” said Lee.
If you live in a place where you can walk to work or school because it’s close and it’s safe, you’re more likely to do that.
But if you have to travel far to work or school, or if your neighborhood isn’t safe, you are less likely to go outside and walk, bike, or run.
Other factors also increase sedentary time, including more screen time, working a desk job, and schools offering less physical education to children.
The slowdown in physical activity and changes in the surrounding environment, though, “preceded the global increase in obesity and are less likely to be major contributors,” wrote the authors of an article published earlier this year in the New England Journal of Medicine.
There is also “evidence to suggest that things like pollution and increased chemicals in our environment may be altering people’s metabolism and microbiome,” said Lee.
Research shows that our microbiome can influence many aspects of our health, including our weight.
In another study, published earlier this year in the journal Diabetes, researchers found that air pollution may contribute to the development of obesity and type 2 diabetes in children.
Medications may also influence metabolism.
More research is needed, though, to fully understand how these factors contribute to obesity around the world.
Reversing the rise in obesity
So far, no country has been able to reverse the rising obesity rates — including the United States, which has been battling it for years now.
One reason for the difficulty may be that the problem requires a different approach than using a medication to treat an illness.
“We have to find some way to reduce the consumption of processed, high-fat foods, and get people to eat more fruits, vegetables, and non-sugary foods,” Thorpe told Healthline.
Researchers are working on figuring out the best ways to make this happen — with some progress in this area.
In the United States, the Medicare-funded Diabetes Prevention Program is a six-month intensive lifestyle program for older adults at risk of developing diabetes.
The program focuses on helping people eat healthier, become more active, and maintain a healthy weight — which is good for preventing many chronic illnesses.
Research has found that this kind of intervention can reduce the number of new cases of diabetes by as much as 58 percent.
These programs are also “easily adaptable to a whole host of other countries,” said Thorpe, and have already been tested in the United States, Finland, China and India.
Thorpe said that some companies in the United States are also nudging employees toward healthier food choices by subsidizing foods like fresh fruits and vegetables, whole grains, and lean sources of protein.
But will it work in other countries?
“It’s something a country like Mexico could do,” said Thorpe.
With 32 percent of its adult population obese, Mexico’s rate is second only to the United States.
However, in order for programs like this to work, Thorpe said they have to be “part of a national strategy on health reform.”
The World Health Organization (WHO) agrees. In a report on approaches to childhood obesity prevention, the WHO writes that community-based interventions need to be supported by appropriate government structures and policies.
This includes things like dedicated funding for obesity interventions, “sugar taxes” to encourage people to cut back on sugar-sweetened beverages, and education campaigns that help people make healthier choices.
Many experts think that it’s also time to stop blaming people because factors out of their control contribute to weight gain and difficulty shedding the pounds.
“We’re continuing to see rises,” said Lee. “The issue is that until everyone recognizes that these are systems problems — and not individual people problems — then the rises will continue.”