Ten times more children and teens obese today than 40 years ago

Type 2 diabetes is typically an adult-onset condition, he told CNN.

Ongoing undernutrition

The new research also revealed ongoing problems on the other end of the body mass spectrum -- being underweight -- with 192 million estimated to be moderately or severely underweight worldwide in 2016. In adults, being underweight is defined as a BMI under 18.5.

Unlike the obesity trend, the number of children and adolescents who are underweight has been declining globally since 1975, the paper found, but numbers remain high.

For example, in India and Pakistan, 50.1% and almost 41.6% of girls, respectively, were underweight in 2016 -- down from 59.9% and 54% in 1975. Numbers were similar among boys in 2016, at 58.1% and 51%, respectively.

Being underweight comes with its own health consequences among children and adolescents, including a greater risk of infectious disease and potential harm during pregnancy for adolescents and women old enough to have children.

"We mustn't forget that undernutrition remains a major global public health problem," commented Dr. Frank Hu, professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health in the United States. Hu was not involved in the research.

"We're experiencing this double burden of undernutrition and overnutrition at the same time," Hu told CNN, adding that "this is nothing new."

When asked about the key findings from this research, Ezzati highlights three points that need the most attention -- that numbers of underweight children is persisting and obesity in high-income countries is plateauing, while the increase has sped up in East Asia. "Obesity and underweight are just as important," he said.

Why it's happening

Over the past four decades, many countries underwent a "nutrition transition" as their economies grew, explained Hu. In those countries, such as India and China, people on the higher socioeconomic end of the spectrum became obese, he said, while people on the spectrum's lower end were underweight -- at first.

"But when countries become more wealthy, the trends become reversed," with the poorer population having access to cheaper, unhealthy foods and richer populations opting for healthier items, said Hu.

"There is a continued need for policies that enhance food security in low-income countries and households, especially in South Asia," said Ezzati. "But, our data also show that the transition from underweight to overweight and obesity can happen quickly in an unhealthy nutritional transition, with an increase in nutrient-poor, energy-dense foods."

We need a healthy transition, Ezzati said.

Experts believe countries therefore need to prioritize both problems, which they have not done to date.

"Our findings highlight the disconnect between the global dialogue on overweight and obesity, which has largely overlooked the remaining under-nutrition burden, and the initiatives and donors focusing on under-nutrition that have paid little attention to the looming burden of overweight and obesity," said Ezzati.

"If programs have always targeted getting more calories into children, they're not prepared when obesity hits, he said.

"Whoever is to blame for this epidemic, it's not the children," Waqanivalu said, adding that governments have created environments in which parents and children are surrounded by unhealthy food options and inadequate options for physical exercise.