Africa has had more success than South Asia in tackling the problem of hunger over the past decade, according to a report on world food production.
Food shortages and malnutrition have been reduced in many parts of Africa, the Global Hunger Index says.
But it remains "extremely alarming" in countries such as Eritrea and Burundi.
The report says India, meanwhile, which has shown strong economic growth, has a disappointing record on tackling the problem.
The wide-ranging report also says the world as a whole is running out of productive land as populations increase.
Produced by the International Food Policy Research Institute, Welthungerhilfe, and Concern Worldwide, the paper identifies 20 countries which have "alarming" or "extremely alarming" levels of hunger.
It gives countries a score based on the proportion of people who are undernourished, the proportion of under fives who are underweight, and the mortality rate of under fives.
Countries in South Asia and Sub-Saharan Africa are the worst affected, it says.
Global Hunger Index
Burundi, Eritrea, Haiti
Ethiopia, Chad, East Timor, Central African Republic, Comoros, Sierra Leone, Yemen, Angola, Bangladesh, Zambia, Mozambique, India, Madagascar, Niger, Dijibouti, Sudan, Nepal
As well as Eritrea and Burundi, which both lie in Sub-Saharan Africa, the Caribbean island of Haiti is categorised as "extremely alarming", with more than 50% of the population undernourished.
Although Haiti had been showing some improvement, the effects of the massive earthquake of 2010 pushed it back into the "extremely alarming" category, the report says.
On the whole, Africa's relatively good performance in tackling hunger over the past decade is partly due to fewer wars, and the fact that governments have become better at concentrating on improving the health of young children.
In South Asia, however, it singles out India for its lack of improvement, despite what it says is impressive economic growth and successful hi-tech industries.
The report says income inequality and the low status of women have had a negative effect on the nutrition of millions of poor families.
The organisations behind the report are calling for governments to do more to safeguard natural resources and address the problems associated with demographic change.
They say climate change is causing flooding, drought and environmental degradation, which all threaten agricultural practices.
Rising global energy prices are also adding to the problem as farmers struggle with heightened costs associated with importing agricultural goods.
They want to see more efficient farming methods, and for the land rights of poor farmers to be strengthened.
The authors also say we are are consuming resources, including fertile land and water, far too quickly.
"Agricultural production must increase substantially to meet the demands of a growing and increasingly wealthy population," said Tom Arnold, Concern Worldwide's chief executive officer.
"Yet to avoid more stress on land, water and energy resources, and to ensure that all have access to adequate food, that production must be sustainable and must prioritise the poor."
Source: BBC News