1.3 billion tonnes of food is wasted globally every year. While carelessness is the main source of blame for food waste in the developed world, the annual food waste in developing countries often comes down to poor infrastructure development and post-harvest losses.

A few weeks before Christmas, 5,000 people gathered in London's Trafalgar Square to eat a free meal made largely from misshapen vegetables and cosmetically imperfect fruits that British supermarkets had refused to sell. The Feeding The 5,000 Initiative was intended to highlight the food waste of supermarkets, as well as that of consumers, in the richest parts of the globe.

The scale of food waste worldwide is mind-boggling. According to a report for the UN by the Swedish Institute for Food and Biotechnology, around 1.3 billion tonnes of food is either lost, or wasted, globally each year. The figure is around a third of the world's total food production; and the study says that reducing losses in developing countries could have an "immediate and significant" impact on livelihoods and food security.

Tristram Stuart, author of Waste, a book about the issues, and organiser of the Feeding The 5,000 event, told the Food Ethics Council's magazine: "There are nearly a billion malnourished people in the world, but all of them could be lifted out of hunger with less than a quarter of the food wasted in Europe and North America. In a globalised food system, where we are all buying food in the same international market place, that means we're taking food out of the mouths of the poor."

Stuart also calculated that the irrigation water used by farmers to grow the food, which would eventually be squandered by its unthrifty buyers, was enough to satisfy the 200-litre domestic water needs of 9 billion people, which is the United Nations' estimate for the global population by 2050.

Further confirmation of the wretched correlation between excessive waste in rich countries, and poverty and starvation in poor ones, came in the 2011 Global Food and Farming Futures report for the British Government.

The report showed that 925 million people worldwide suffer from hunger because they cannot get adequate supplies of the proteins, carbohydrates and vitamins required for good health. Another billion people suffer from 'hidden hunger', which means they are missing out on vitamins and minerals and at risk from physical and mental impairment. Meanwhile, in the richer countries, a billion people over-eat, causing epidemics of Type 2 diabetes and heartdisease.

The Government report added that the 40 million tonnes of food wasted by US households, retailers and food services each year would be enough to satisfy the hunger of the world's starving millions.

But establishing direct links between the first-world's profligate approach to food and third-world poverty is a complex matter, according to Professor Peter Hazell, of the Centre for Development, Environment and Policy, at London's School of Oriental and African Studies.

Professor Hazell does not share Tristram Stuart's belief that eliminating waste in rich countries would have a dramatic influence on starvation levels in the poor world.

"I ask my students what would happen to starving families in Africa if a million westerners did not eat their hamburgers today and the answer, unfortunately, is not a lot," he said. "There would be some beneficial effects for the environment through reduced carbon emissions, but the world's food problems are less about quantity, and more about distribution. Basically the people who need it the most are the ones who can't afford to buy it."

But Professor Hazell conceded that there was a small correlation between waste in the West and higher global food prices.

"We are net exporters of food to the developing world, so the more we overeat and waste, the less we have to export, so food prices do go up, but only a little. A much greater effect was seen when the Americans removed 40 percent of their maize from the world market to make biofuels. It was such a huge amount that it became a major factor in the escalating food crisis in 2008."

The world's poorer nations though are not so nearly as careless with their food as Westerners.Consumers in sub-Saharan Africa, as well as South and Southeast Asia, throw away only 6-11 kg a year compared to 95-115 kg a year in Europe and North America.

The more fundamental problem for poorer nations is "food loss", 40 percent of which occurs at post-harvest. The annual cost of post-harvest losses in Sub-Saharan Africa, is measured in the billions of dollars and the human cost is, of course, incalculable.

The UN assessed the scale of African post-harvest losses and proposed solutions in its reportMissing Food: the Case of Postharvest Grain Losses in Sub-Saharan Africa.

The report found that in Eastern and Southern Africa, food losses were $1.6 billion per year, about 13.5 percent of total grain production. Figures are unavailable for Central, or West Africa, but assuming losses of a similar magnitude, the value of post-harvest grain losses in sub-Saharan Africa could total $4 billion a year out of an estimated production worth of $27 billion. This missing food could meet the minimum annual food requirements of at least 48 million people, the report said.

Losses occur when grain decays, or is infested by pests, fungi or microbes. But post-harvest losses also result from low prices and lack of access to markets because of disorganised supply chains and terrible transport infrastructure. Many African farmers, for instance, live far away from good roads.

A variety of technologies can reduce post-harvest losses, including crop protectants and storage containers, such as hermetically sealed bags and metallic silos. Some of the methods which have worked well in Asia, such as small-scale rice-drying technology and the introduction of pedal threshers and rice mills, have also been adopted successfully in parts of Africa.

Practical Action, a development non-​profit organisation that uses technology to help people gain access to clean water and sanitation and improve their food production, provides homemade clay refrigerators, known as 'zeer pots', which can be built from mud, clay, water and sand.

In a zeer pot, tomatoes and carrots can last up to 20 days, while okra will last 17 days. Practical Action also provides trainings and demonstrations to teach small-​scale farmers how to make and use the pots in developing regions such as Sudan and Darfur.

Meanwhile, in Kenya, the Food and Agriculture Organisation (FAO) teamed up with the Ministry of Agriculture to train farmers to take steps to reduce maize crop losses to mycotoxin, the by-​product of fungi growth. In Afghanistan, the FAO provided metallic silos to 18,000 households to improve post-​harvest storage. Farmers use the silos to store cereal grains and legumes, protecting these crops from weather and pests. As a result, post-​harvest losses have dropped from between 15 and 20 percent to less than 1 or 2 percent.

Professor Hazell agrees that simple technologies can boost post-harvest yields, but he argues that many of the technologies are beyond the means of most small-scale African farmers.

Africa's farmers, he says, are struggling to survive. Their outmoded equipment produces practically the same yields as 40 years ago. And farm sizes are shrinking forcing them to migrate to the cities, where they often struggle to find jobs.

Asian farmers faced a similar crisis in the 1960s, but large-scale government investment (10-15 percent of the Government's annual budget) was invested in agricultural research, irrigation, rural roads and power. The governments also offered financial support for small-scale farmers. These enlightened policies created a lot of jobs in agriculture and related industries, reduced food prices, and alleviated poverty.

"Simple things like sealed plastic storage bags tend to be too expensive and most African farmers can't afford it. They are made from heavy plastic, which has to be imported and purchased. So they are relatively expensive," he said

But African governments have not been so proactive. They have spent just 5-6 percent of their total budget on agriculture for the past 40 years. One consequence of their laxity is the terrible state of rural infrastructure in Africa, which is another one of the major reasons for food loss. High transport and marketing costs make it difficult to supply food efficiently to consumers. Yields could be dramatically increased through better technologies and improved infrastructure.

"As African governments are failing to build the infrastructure of investment, we've seen an explosion of private-sector investment from the BRIC countries in Africa, which they see as one of the last great frontiers in agriculture," Professor Hazell said.

The investment, however, is double-edged as far as Africa is concerned. The foreign supermarkets and private investors increase yields and reduce greatly losses along the supply chain by introducing cold storage facilities. But they also pile more pressure on Africa's beleaguered farmers.

"There are positive aspects as greater food production lowers prices, gets more food into urban areas and creates jobs," said Professor Hazell.

"But it's not always good for the small farmers as it's hard for them to link into the value chains once they are taken over by corporate players. The foreign investors are often referred to as 'land grabbers'."

The investors are a mixture of sovereign and private companies. The sovereign companies are often Chinese and invest on a major scale.

"The Chinese Government is concerned about feeding its enormous population, so although they are building new roads and ports, and storage facilities,the food will be shipped straight out of Africa to feed the Chinese, and not Africans," he said. "The Chinese want to control the land, the value chain and production. The fact they are able to do so reflects the failure of African governments to develop their own agricultural potential. It's waiting for someone else to develop it."

Whether or not it directly impacts on starvation and malnutrition in the third world is a matter for debate, but the sheer scale of food waste in Western nations is shocking.

Every day, the average American throws away about one-and-a-half pounds of food which adds up to 31 million tonnes in landfills each year. This waste produces 34 percent of the US total of methane, a greenhouse gas more than 20 times as potent as carbon dioxide. The US Department of Agriculture estimated that recovering just 5 percent of the food that is wasted could feed four million people a day and recovering 25 percent would feed 20 million people.A lot of food is thrown away, but so much excess is bought that around 63 percent of adult Americans are overweight, or obese, according to a US Government health survey.

In Britain, the scale of waste is much the same. Every year UK households bin one-fifth of the food they buy. Of the 7.2 million tonnes wasted in 2010, just over four million tonnes could have been eaten, costing £12 billion. A report for the Government-funded WRAP (Working Together for a World Without Waste) said that 17 million tonnes of carbon dioxide was emitted during the processing and transporting of this wasted food, which equates to one in five cars on British roads.

To give some idea of the scale of the waste, the WRAP report calculated that 359,000 tonnes of potatoes, 190,000 tonnes of apples and 782,000 tonnes of baked products were binned each year. Unsurprisingly, the supermarkets are one of the worst offenders. Of the 16 million tonnes of food and drink wasted each year, they produce some 1.6 million tonnes.

Hannah Johnson from Resource Futures, a UK consultancy that led the report's research, said the losses were unsustainable given the increasing stress on the global supply chain.

"The global population will rise from seven billion to nine billion by 2050, competition for land and water is intensifying, and climate change effects are emerging," she said.

Johnson said there were some signs the message was getting through to consumers. WRAP figures show that the UK has cut household waste by 13 percent since 2007.

In the supermarkets, research into date labelling has shown that many consumers gave confused the 'display until' dates, which are used by retailers to control stock, with the 'use by' or 'best before' dates. The UK government has agreed that food packaging should only carry a 'best before' or 'use by' date, and WRAP is now pressing to change 'freeze on day of purchase' labels to 'freeze before the date marked'.

Smart technology is being designed which will soon be able to alert people in the supply chain, or consumers, that food is going to go off," said Johnson. "The packaging will turn a different colour to indicate that it's the last chance to eat it. This is not available yet but soon will be. These are the kinds of innovations we need, but educating the public about food is also vital to tackle excessive consumption and waste."

David Smith writes for the Economy Watch where this article was originally published.