The United Nations marked World Food Day on Wednesday, warning against food waste as 842 million people go hungry and stressing the importance of healthy diets amid rising obesity.
Around a third of food produced globally currently goes to waste - some 1.3 billion tonnes a year according to the Rome-based UN Food and Agriculture Organisation (FAO).
"With just a quarter of that, we could feed the 842 million hungry," said Robert van Otterdijk, an agriculture industry expert at FAO.
Halving the amount of food wasted would mean having to raise world food production by 32 per cent to feed the world's population in 2050, instead of the 60 per cent currently estimated.
Mathilde Iweins, coordinator of a report on the cost of food waste, said that "the agricultural areas used to produce the food that will never be eaten are as big as Canada and India combined".
But the FAO said focusing on the type of food being consumed was just as important, warning that malnutrition and poorly-balanced diets impose high costs on society - from towering health care bills to lost productivity.
"One out of every four children in the world under the age of five is stunted," the FAO said in a report.
"This means 165 million children who are so malnourished they will never reach their full physical and cognitive potential," it said.
About two billion people in the world lack vitamins and minerals that are essential for good health while 1.4 billion people are overweight.
Children with stunted growth may be at greater risk of developing obesity problems and related diseases in adulthood in a worrying cycle of malnutrition.
Of those overweight "about one-third are obese and at risk of coronary heart disease, diabetes or other health problems", the FAO said.
The agency said that while wiping out malnutrition worldwide "is a daunting challenge, the return on investment would be high".
"If the global community invested $1.2 billion (S$1.4 billion) per year for five years on reducing micronutrient deficiencies, the results would be better health, fewer child deaths and increased future earnings," it said.
"It would generate annual gains worth $15.3 billion," it added.