Intermediate 
If the amount of food wasted around the world were reduced by just 25%, there would be enough food to feed all the people who are malnourished, according to the UN. Each year, 1.3bn tonnes of food, about a third of all that is produced, is wasted. This includes about 45% of all fruit and vegetables, 35% of  sh and seafood, 30% of cereals, 20% of dairy products and 20% of meat. Meanwhile, 795 million people suffer from severe hunger and malnutrition.
The UN identi es the problem of food waste as one of the great challenges to achieving food security. By 2050, food production will have to increase by 60%, compared to 2005 levels, to feed a growing global population. Reducing food waste would help to meet future demand.
The problem is global but appears in very different ways. In developing countries, there is a lot of food loss, which is unintentional waste, often due to poor equipment, transportation and infrastructure. In wealthy countries, there are low levels of food loss but high levels of food waste, which means food is thrown away by consumers because they have purchased too much or by retailers who reject food because of strict standards of appearance.
In developed countries, consumers and retailers throw away between 30% and 40% of all food purchased, whereas, in poorer countries, only 5% to 16% of food is thrown away.
In the developing world, food waste is almost non-existent, says Robert van Otterdijk, coordinator of the UN Food and Agriculture Organizations Save Food programme. Food waste is happening in countries where people can afford to throw away food. But, on the other hand, there are a lot of food losses in developing countries because of the underdeveloped conditions they have.
The environmental impact of food loss and waste is high. The carbon footprint of food produced and not eaten is estimated at 3.3 gigatonnes of CO2  this means that, if food waste were a country, it would be the third highest emitter of greenhouse gases after the US and China. About 30% of available agricultural land is used to grow or farm food that is subsequently wasted. And more surface and groundwater is used to produce wasted food around the globe than is used for agriculture by any single country, including India and China.
Climate change is caused by our economy of production and consumption because it is out of balance with what the Earth can provide, says van Otterdijk. Production of food is one of the biggest production sectors in the world and, if one-third of all this is wasted, you can imagine what a huge effect this has on the natural resources  on land, water, energy and greenhouse gas emissions.
The places that waste the most food are the US, Canada, Australia and New Zealand, where consumers waste 39% of all food purchased. Next is Europe, where about 31% of all food purchased by consumers is thrown away. In the UK, 15m tonnes of food is lost or wasted each year. British consumers throw away 4.2m tonnes of edible food each year. This means that 11.7% of all food purchased is wasted, which costs each family 700 a year.
The foods most commonly found in British bins are bread, vegetables, fruit and milk. The most wasted food in the UK by weight is bread, with consumers throwing away 414,000 tonnes (22.4%) of all bread purchased. By percentage, the most wasted food is lettuce and leafy salads, of which consumers throw away 38% (64,000 tonnes) of all they buy.
The UK has made progress in the past ten years after a campaign to reduce waste. Van Otterdijk says the UK has been very successful in combating food waste. Between 2007 and 2012, the amount of food waste produced by UK households decreased by 21%, from 5.3m tonnes to 4.2m tonnes, largely due to greater awareness.
Van Otterdijk says there has been a very encouraging, unexpected, continuing interest in food waste and this enables campaigns around the world to gain momentum. We have to do much more and it needs the participation of public and private sectors, he says. But, if it continues like this, maybe, after ten years, well have globally signi cant results.