1 in 8 people worldwide now have obesity. Here's what to know.

On March 1, the World Health Organization (WHO) reported findings from a recent Lancet study that revealed 1 in 8 people worldwide are now living with obesity. More specifically, the latest data reveals that, in 2022, 2.5 billion adults (or 43%) were overweight; of those, 890 million adults were living with obesity — a figure that's more than doubled since 1990. Adolescent obesity has quadrupled since 1990, with 160 million 5- to 19-year-olds considered obese.

But what's the difference between being overweight and being obese? And as the WHO report renews calls to help prevent and manage obesity on a global scale, what are some interventions that can help? Here's what to know.

Obesity vs. overweight

Obesity is "a chronic relapsing disease characterized by excess deposits of fat that can impair health," says Dr. Francesco Branca, director of the department of nutrition and food safety in the WHO. More simply, he tells Yahoo Life that it's "a more severe form of overweight." The differentiating factors are the health risks that obesity is associated with.

According to the WHO, obesity leads to higher risk of:

• Cardiovascular disease

• Type 2 diabetes

• Kidney disease

• Certain cancers

• Issues with bone health

• Reproductive health issues

• Impaired daily functions, such as moving and sleeping

Branca says that comorbidities of obesity — which include health conditions such as diabetes, hypertension and obstructive sleep apnea — account for about 5 million deaths globally every year.

Overweight, on the other hand, isn't correlated with any "reliable increased risk of morbidity and mortality," Dr. Melanie Jay, director of NYU Langone’s Comprehensive Program on Obesity, tells Yahoo Life. "But we know that when someone is in the quote unquote overweight range, they have higher risk of developing obesity in the future," as a result of natural weight gain patterns.

Each condition is defined by body mass index, which is said to measure body fat based on a person's height and weight. Although the measurement tool is controversial, it is used as a screening method for weight categories such as:

• Normal: a BMI under 25

• Overweight: BMI from 25 to 29.9

• Obese: BMI 30 and above

Jay says BMI is "useful on a population level" for the sake of predicting levels of adipose tissue and fat, and therefore, rates of obesity. On an individual level, however, there are more metrics of health that need to be taken into account. For example, blood sugar levels, cholesterol and other factors are among the things that Jay looks for in her own patients. Other physical measurements, such as waist circumference, are also taken into account. "There are people who have higher body mass index that would be considered higher risk, but they individually are not because they are not having the same co-morbidities or complications at that BMI," she says.

On the flip side, "You can have people in the overweight range who still have a lot of visceral fat, a lot of weight gain in their abdomen, who have a family history of diabetes, who might have pre-diabetes or diabetes. So that's more important than their BMI at that point." She adds that the measure alone "is not a good indication of health."

Social determinants of health — defined by the Centers for Disease Control and Prevention (CDC) as "non-medical factors that influence health outcomes," such as the conditions under which people live and work, along with racism and climate change — also play a role in the likelihood of having obesity versus being overweight.

What causes or contributes to obesity?

Branca says that the disease results from "an energy imbalance, generated by unhealthy dietary intakes and inadequate levels of physical activity." And while weight bias contributes to the belief that obesity is a result of personal responsibility, experts say there's very little of that playing a role in a person's diagnosis.

"Obesity is always an interaction of genetic predisposition and the environment that someone is living in, including the people they interact with and the food that's available. And then there are medications and other things that increase the risk of obesity and cause people to gain weight," explains Jay. "Most of obesity has nothing to do with personal choices."

A spokesperson for the division of nutrition, physical activity and obesity at the CDC agrees, telling Yahoo Life: "Neighborhood design, access to nutritious, affordable foods and beverages and access to safe and convenient places for physical activity can all impact weight and health. The racial and ethnic disparities in obesity underscore the need to address factors that influence health and remove barriers to it, such as poverty, education and housing."

This is why Jay says that obesity prevention requires high-level interventions. "That means structuring society so that healthier choices are automatic and easier, addressing our global food supply to have healthier choices and enough fruits and vegetables, and having built environments with opportunities for people to walk more and to do more physical activity safely."

The bottom line, says Jay, is that "there are things that we know are fueling this global surge of obesity rates and then I think there's still a lot of things we don't know." And because prevention is important in decreasing rates of obesity, experts say more attention needs to be paid to policies and their impact.

What does treatment look like?

"Treatment of obesity requires an integrated approach, including long-term support of lifestyle changes provided by a well-trained team of health practitioners — doctors, dietitians, psychologists — possibly accompanied by pharmacological and/or surgical treatment, depending on the severity of the condition," explains Branca.

Jay says that "we've all heard about the newer injectable medications. But there's also several medications that have been around longer, that are less expensive and might be more available at this moment." But, she points out, "we have 1 billion people" living with obesity. "We want to prevent it," she says. "We do need a lot more research and to be trying a lot more things when it comes to obesity prevention or even preventing further increases in the rates of obesity."