More than 10 percent of the world’s population is now obese, a marked rise over the last 30 years that is leading to widespread health problems and millions of premature deaths, according to a new study, the most comprehensive research done on the subject.
Published Monday in The New England Journal of Medicine, the study showed that the problem had swept the globe, including regions that have historically had food shortages, like Africa.
The study, compiled by the Institute for Health Metrics and Evaluation at the University of Washington and funded by the Gates Foundation, looked at 195 countries, essentially the world’s population, finding that rates of obesity at least doubled in 73 countries — including Turkey, Venezuela and Bhutan — from 1980 to 2015, and “continuously increased in most other countries.”
Analyzing some 1,800 data sets from around the world, researchers found that excess weight played a role in four million deaths in 2015, from heart disease, diabetes, kidney disease and other factors. The per capita death rate was up 28 percent since 1990 and, notably, 40 percent of the deaths were among people who were overweight but not heavy enough to be classified as obese.
The study defined obese as a body mass index of 30 or higher and overweight as a BMI from 25 to 29.
By those measures, nearly 604 million adults worldwide are obese and 108 million children, the authors reported. Obesity rates among children are rising faster in many countries than among adults.
In the United States, 12.5 percent of children were obese, up from 5 percent in 1980. Combining children and adults, the United States had the dubious distinction of having the largest increase in percentile points of any country, a jump of 16 percentage points to 26.5 percent of the overall population.
A range of nutrition scientists, including ones who differ significantly on some issues in the field, uniformly praised the breadth, depth and quality of the study, and the significance of its message.
“Its global implications are huge,” said Barry Popkin, a professor of nutrition at the University of North Carolina. He echoed others in saying the findings tend to also affirm smaller, more regional studies.
“This study shows what we know: No country in the globe has reduced overweight or obesity levels. This is astounding given the huge health and economic costs linked with overweight and obesity.”
The study largely did not go deeply into the causes of obesity, but the authors said the growing accessibility of inexpensive, nutrient-poor packaged foods was probably a major factor and the general slowdown in physical activity was probably not.
“The change in physical activity preceded the global increase in obesity,” said Dr. Ashkan Afshin, assistant professor at the Institute for Health Metrics and Evaluation and lead author of the study.
“We have more processed food, more energy-dense food, more intense marketing of food products, and these products are more available and more accessible,” he added. “The food environment seems to be the main driver of obesity.”
Others agreed on the availability of poor diet, noting that such food can often be the most accessible and affordable.
“What people eat is the key factor in whether they become obese or not,” said Adam Drewnowsk, director of the Center for Public Health Nutrition at the University of Washington, who was not affiliated with the study, which he deemed “brilliant work by the best people in the business.”
He said getting people healthy food was easier said than done.
“It is all very nice to talk about the need to eat less unhealthy foods and more healthy foods,” he said. But “unhealthy foods cost less; healthier foods often cost more. People eat what they can afford.”
The research characterized growth of obesity in two ways, one that looked at countries that had the biggest leap in percentage points. After the United States, other countries with particularly significant jumps in percent of the population who are obese included Saudi Arabia, Algeria and Egypt.
But other countries had rates that rose much faster, even though they remained lower as an overall percent of the population. Broadly, the regions with the fastest rises were Latin America, Africa and Southeast Asia, notably China.
In China, for example, less than 1 percent of the population was obese in 1980, but now more than 5 percent is, a fivefold increase. The rise in childhood obesity in China roughly paralleled that overall change.
Three countries in Africa — Burkina Faso, Mali and Guinea-Bissau — had the fastest growth. Burkina Faso, the country with the fastest growth in the world in obesity, began in 1980 with around one-third of a percent of its population as obese. Its rate rose to nearly 7 percent of the population.
“The future health and economic burden facing all these countries is immense,” Popkin said.
Regarding the overall health implications of the study, one point made by the researchers is that there is a good news/bad news pattern emerging. The good news is that the disease burden caused by obesity is actually falling in some of the wealthiest nations. In the United States, the death rates associated with obesity fell from 63 per 100,000 in 1990 (the baseline year for this measure) to 61 per 100,000 people, reflecting medications that deal with the effects of obesity, like hypertension.
The bad news is those remedies are not available in developing countries or are available only to the wealthiest people, leading to growing rates of associated deaths and without a clear solution.
“Most of the obese people are dying because of cardiovascular disease and diabetes,” said Afshin, lead author of the study. That has been somewhat mitigated in the United States “and other developed nations” with the use of drugs.
“But we cannot have all people on drugs,” he said. “Ideally, we want to go to the root causes and address the problem of overeating.”
To date, he said, no country “has been able to control the food environment, which seems to be the main driver of obesity.”