The number of people facing food shortage and undernourishment rose in 2017 to 821 million, meaning the problem affects one person in every nine, according to a report compiled by United Nations organizations.

The uptick in global undernourishment was particularly focused in South America and Africa, according to the report The State of Food Security and Nutrition in the World.

"For the third year in a row, there has been a rise in world hunger. The absolute number of undernourished people, i.e. those facing chronic food deprivation, has increased to nearly 821 million in 2017, from around 804 million in 2016," the report warned. "These are levels from almost a decade ago," it added.

In Africa, an estimated 256 million people, or 20 percent of the population on the continent, were affected by undernourishment in 2017, often due to crises related to either adverse weather trends such as drought or armed conflict.

Heavily populated Asia saw its downward trend in the number of hungry slow slightly in 2017 as researchers documented roughly 515 million people, or 11.4 percent of the population, suffering from food shortage.

Economic crises in South America, especially in Venezuela, spurred a slight increase in the number of undernourished to 39 million people, or 6.1 percent of the total population including the Caribbean region.

With regards to children, the report found that 7.5 percent of children, some 50.5 million globally, showed signs of wasting due to lack of food, while 5.6 percent of children were found to be overweight, a figure that has scarcely budged sine 2012.

"Adult obesity, on the other hand, is worsening," the report warned. "Adult obesity rates continue to rise each year, from 11.7 percent in 2012 to 13.2 percent in 2016. This means that in 2017 more than one in eight adults, or more than 672 million, in the world is obese," it added.

The UN for an increased international effort to tackle conflict and climate change, citing those as driving factors in the hunger crisis.