So what does it mean to be hungry?

That's a question that occurred to us as we read some encouraging news: The world isn't as hungry as it used to be.

A U.N. report has noted that 795 million people were hungry in the year 2014. That's a mind-boggling number. But in fact it's 200 million lower than the estimated 1 billion hungry people in 1990.

The improvement is especially impressive because the world population has gone up by around 2 billion since the '90s.

And the rate of hunger is also declining. Only 12.9 percent of the population in developing regions are hungry today, compared to 23.3 percent a quarter century ago.

Here's a look at what hunger is like — and why it's declining.

The Hungry Person's Diet

The world's hungry people consume fewer than the 2,000 or so daily calories the average person needs to survive (the amount varies based on age, gender and energy expended).

There are two reasons for this calorie deficit, says Pedro Sanchez, director of Agriculture and Food Security Center at Columbia University. There's acute hunger: When sudden conflicts and disasters like a drought leave people starving.

That accounts for less than 10 percent of the hungry population, according to the World Food Program.

The more prevalent type is chronic hunger, which happens mainly in rural areas and among the poorest of the poor.

People who are chronically hungry do eat. But their diet tends to consist of food like cereal, corn, cassava and rice — high in calories and carbohydrates but not much else.

Even then, these people eat so little that the carbs barely fill their stomach with the calories they need. And they don't eat the vegetables, meat, fish and/or dairy products that provide ample protein, vitamin A, zinc, iron and iodine, says Pedro Sanchez, director of Agriculture and Food Security Center at Columbia University.

What Hunger Does To The Body...

A person who is chronically hungry would feel more than just hunger pangs. The body produces less energy and develops a daily sense of weakness. "They feel tired, they don't feel like they can perform their work optimally," says Rafael Perez-Escamilla, a chronic disease epidemiologist at Yale University. "They feel fatigued and a sense of apathy." He adds that the hunger can become so severe that a person barely has the ability to get up from bed.

The lack of nutrients is especially detrimental for children under 5, for whom hunger is the leading cause of death. Each year, hunger kills some 3.1 million children under 5, accounting for 45 percent of child mortality within that age group. Those who survive suffer a lack of physical and mental development. Roughly 100 million are underweight, and 1 in 4 children are stunted, meaning their height is below the fifth percentile for their age.

... And To The Brain

Perez-Escamilla warns that the physical consequences are only part of the problem. "The vast majority of people facing chronic hunger cannot concentrate very well," he says. "You start having a headache and getting into a bad mood, and you can't concentrate on your work."

Now, he says, imagine that happening every day. Add the distress of not being able to provide for your family. He recalls a study in which he asked people what hunger meant. "People talked about how hunger is the worst form of violence against human beings," he says. "It's the worst thing that can happen to the dignity of a human being."

Why Hunger Is Declining

Against that stark backdrop of hunger and death comes the good news about a dropoff in world hunger.

"I was basically in tears," says Pedro Sanchez of Columbia University.

While he wasn't involved in this latest State of Food Insecurity report from the Food and Agriculture Organization, Sanchez coauthored another U.N. report back in 2005 laying out a series of recommendations on how to cut hunger in half in the developing world. Its ambitious title: "Halving Hunger: It Can Be Done." And 72 of 129 developing countries surveyed have met that goal.

"That's happened in huge countries with enormous populations such as Nigeria and Ethiopia, and also in [smaller] countries like Malawi, Ghana, Mali," he says. "This is fantastic."

The first step is getting those calories in by filling their stomachs with "maize, flour, rice and the like," says Sanchez. To curb vitamin and mineral deficiency, foods like protein-rich legumes (peanuts, beans and soybeans), milk, fish and meat should be introduced.

The best way to do that, Sanchez says, is to in increase the yield of crops in small farming communities by providing seeds selectively bred to produce crops that can survive the harsh weather in some of these countries — as well as training small farmers to use manure and other fertilizers to improve the soil.

And those small family farms made a difference. When they become more productive, there's more food on the table but and more income to buy other nutrient-rich foods.

The report also cites government programs for making a dent in hunger.

Take Brazil, for example, says Rafael Perez-Escamilla at Yale. A multimillion-dollar program called Bolsa Familia rewards families with money for doing things like attending health and nutrition classes, sending kids to school and taking the family for checkups. And ideally, they can use the cash they receive to buy healthful food for the family.

What Gets In The Way Of Cutting Hunger

The U.N. report notes that the overall progress has been uneven. Some countries like India, Kenya and Liberia report little or no progress. "With Somalia, with all sorts of civil wars, the government is worried about other things unfortunately," Sanchez says.

And in Ebola-stricken countries like Liberia, the disease took a toll as did inadequate government response to the outbreak, adds Perez-Escamilla.

When Hunger Ends, Other Problems Begin

If and when hunger is just a memory, other food-related problems will take its place. "This is not an issue of just fattening people up," says Perez-Escamlla.

"In many countries, the problem now is becoming obesity," he says. "The big challenge ahead is not only ensuring that everybody has enough calories but that we ensure that everyone has access to healthy diets — fruits, vegetables, fish — and significant reduction in the consumption of junk foods."

He points to Mexico, which has reduced hunger but has also become among the fattest countries in the world, with a third of adults reported as obese. "What's happening in Latin America should not be happen in Africa," he says, where countries are starting to record high numbers of heart disease and diabetes.

Copyright 2016 NPR. To see more, visit