Sugary beverages and soft drinks are a leading cause of a growing epidemic of obesity in Africa, according to a new report from the World Health Organization.

The number of obese children across the continent has doubled from 5.4 million in 1990 to 10.3 million in Africa today, the WHO's Commission on Ending Childhood Obesity found.

And while soft drinks are a focal point of the report, the commission said that African countries' rapid economic and social change were two primary, environmental culprits driving the trend. As the continent's once-rural populations continue to coalesce around urban areas, African children are exercising less, taking public transportation instead of walking, playing indoors instead of outdoors, and have access to a greater number of unhealthy food choices.

"There's been a great change with people moving from the countryside to the city," Juana Willumsen, a member of the team working with the WHO Commission on Ending Childhood Obesity told Radio France International. "This results in a change in traditional diets. People have also become more sedentary. They start taking public transportation and cars instead of walking."

In many of the countries, populations also face a lack of access to nutrient-dense food and information about proper nutrition. The result is often malnutrition and, paradoxically, obesity, according to the report.

"Children are exposed to ultra-processed, energy-dense, nutrient-poor foods, which are cheap and readily available," it says.

There has also been an uptick in marketing of junk foods to children, the report said.

"Despite the increasing number of voluntary efforts by industry, exposure to the marketing of unhealthy foods remains a major issue demanding change that will protect all children equally," the report says.

The consequences of widespread obesity can be taxing on both individuals and a country's economy, according to Dr. Sania Nishtar, who co-chaired the commission that produced the report. Nishtar said in a statement accompanying its release that the physical, psychological, and health consequences of being an obese child include a negative effect on educational attainment, which can result in economic loss for them, their families, and their society as they grow up.

The WHO found that Africa accounted for nearly 25 percent of the world's 41 million overweight children under the age of 5, another 50 percent of whom live in Asia. That number is expected to increase to 70 million over the next 10 years, though the report included strategies and recommendations it hopes will curb that growth, including a tax on sugary drinks, a ban on advertising to children, promoting breastfeeding for infants, and increasing access to and awareness of nutritionally-dense foods.

Karen Hofman, a researcher at South Africa's Wits University, told the country's Timesnewspaper that the report's recommendation of a sugar tax was "exactly what is needed" to curb the country's addiction to soda. Hofman found in her research that more than 50 percent of schools in Soweto, South Africa, had advertisements for soda in the schools, despite signing a pledge not to advertise junk food to children.

The country's beverage industry, however, condemned the idea, saying it was "discriminatory."

A tax on soft drinks was famously proposed in the United States by New York City Mayor Mike Bloomberg and met with a flood of criticism and pushback by the beverage industry, which lobbied heavily to defeat the proposal. The WHO said a tax would be most beneficial to helping prevent obesity among low-income families.

"Fiscal policies may encourage this group of consumers to make healthier choices (provided healthier alternatives are made available) as well as providing an indirectly educational and public health signal to the whole population," the report says.

The report encourages non-government organizations, non-profits, and universities to keep studying and publicizing the problems associated with obesity, but concludes by noting that governments bear the "primary responsibility" of ending the crisis, and must use their regulatory authority to do so quickly.

"Increased political commitment is needed to tackle the global challenge of childhood overweight and obesity," Sir Peter Gluckman, a New Zaeland doctor and public health official who chaired the commission, said in a statement.

Gluckman said the WHO should work with governments on implementing plans to change the "environmental causes of obesity...and help give children the healthy start to life they deserve."