Despite a drop in the number of people facing starvation, nearly one in three of the world's population are malnourished, even as obesity spreads around the globe, an international food security think-tank said on Tuesday.

Stunting - children too short for their age due to a poor diet - affects more than 160 million children under five years old, the International Food Policy Research Institute said in its Global Nutrition Report.

The number of hungry people in the world fell, but obesity rose between 2010 and 2014 "in every single country", and one in 12 adults worldwide now has Type 2 diabetes, the report said.

Adult diabetes is increasing in 185 countries and is decreasing or stable in just five.

"Too often people think of malnutrition as just a problem of hungry kids in the poorest countries... (it) has many forms and affects all countries, rich and poor alike," Corinna Hawkes, co-author of the report, said in a statement.

"The coexistence of nutritional problems associated with extreme deprivation and obesity is the real face of malnutrition."

Globally, two billion people are not eating the proper amounts of vitamins and minerals, and thus face micronutrient malnutrition, while 1.9 billion adults are overweight or obese.

Forty-five per cent of all deaths of children under five are related to malnutrition, the report said.

In five large developing countries - Bangladesh, the Democratic Republic of Congo, Ethiopia, Nigeria and Pakistan - the per centage of children under five who are not stunted or wasted (underweight for their age) ranges from 43 to 48 per cent.

Childhood malnutrition will have a dangerous impact on future development in those countries with fast-expanding populations, as children will not reach their full physical or intellectual potential as adults, it said.

The report, published before a United Nations summit to establish a new set of Sustainable Development Goals on reducing international poverty, said governments should spend more than the 1.3 per cent of their budgets they currently allocate on average for nutrition-related programmes.

One dollar invested in nutrition-related programmes offers a return of up to $16 in economic benefits, the report said, such as increased productivity and lower healthcare costs.

"People cannot get anywhere near their full potential without first overcoming malnutrition," Lawrence Haddad, the report's lead author, said in a statement.

"This not only jeopardizes the lives of those who are malnourished, but also affects the larger framework of economic growth and sustainable development." – Reuters