Is almost half of the world's food 'wasted'?

This article was updated on 14 January. See below for changes.

"Half of all food 'wasted', report claims"

BBC News, 10 January 2013

"Almost half of the world's food thrown away, report finds"

The Guardian, 10 January 2013

The Institution of Mechanical Engineers (IME) made headlines today after it released a report entitled 'Global Food - Waste not, want not'. Several news outlets produced articles on the findings, the most startling of which suggested that up to half of all the food produced in the world is wasted.

But what do we mean by 'waste'? And are we really this profligate?

To check all the claims from the report would take some time, so for now its worth just looking at what's made it to the headlines. Let's take the key claim from the horse's mouth (that's the IME's press release):

"A new report by the Institution of Mechanical Engineers has found that as much as 50% of all food produced around the world never reaches a human stomach due to issues as varied as inadequate infrastructure and storage facilities through to overly strict sell-by dates, buy-one-get-one free offers and consumers demanding cosmetically perfect food."

In the report itself the IME claims that 4 billion metric tonnes of food is produced globally every year, of which it's estimated that 30-50%, or between 1.2 and 2 billion metric tonnes, is "lost or wasted every year before consumption".

Where do these figures come from?

The report draws on two sources: the first is a study from the UN Food and Agriculture Organization (FAO). They used data gathered by the Swedish Institute for Food and Biotechnology (SIK) and their own statistical yearbook to determine that:

"The results of the study suggest that roughly one-third of food produced for human consumption is lost or wasted globally, which amounts to about 1.3 billion tons per year." [emphasis added]

The second source cited is a report from the Stockholm International Water Institute (SIWI). It used findings from a 2000 academic paper to conclude that:

"losses and wastage may be in the order of 50 percent between field and fork" [emphasis added]

It's quite possible these are the specific claims that lead to the 30-50% estimate for the proportion of food that is wasted, although Full Fact is waiting to hear back from the IME for more detail on where its figures are from.

What do we mean by 'wasted'?

Most news outlets covering the story were content to report from this that nearly half of the world's food is "thrown away" or "goes to waste". But is this the case?

The researchers at the FAO - who made the estimate of one-third wasted - define very clearly what they're referring to:

"Food losses refer to the decrease in edible food mass throughout the part of the supply chain that specifically leads to edible food for human consumption. Food losses take place at production, post harvest and processing stages in the food supply chain. Food losses occuring at the end of the food chain (retail and final consumption) are rather called "food waste", which relates to retailers' and consumers' behavior." [emphasis added]

In other words, waste is what consumers and supermarkets are [to an extent] to blame for, while losses happen as the food is being produced.

The SIWI provide a more visual description of where waste and losses occur, including food losses that go towards animal feed:

So the 'half' of food that is 'wasted' actually seems to include a reasonable portion of food that goes towards animal feed. On this reading it would be wrong to understand the figures as meaning that half of the world's food simply rots away. Instead, this estimate seems to be saying that only half of the world's food makes it 'from field to fork'.

If we want to measure waste alone, it's reasonable to exclude food that isn't intended for the table. In fact, this is exactly what the UN's FAO study does:

""Food" waste or loss is measured only for products that are directed to human consumption, excluding feed and parts of products which are not edible. Per definition, food losses or waste are the masses of food lost or wasted in the part of food chains leading to "edible products going to human consumption"... This approach distinguishes "planned" non-food uses to "unplanned" non-food uses, which are hereby accounted under losses."

Full Fact's sister site Straight Statistics has made a similar point before in relation of claims that Britain wastes a third of the food it buys. Figures for the amount of food wasted in the UK include a category for food that is 'composted and fed to animals'. While this may strictly be 'waste', it doesn't necessarily mean that none of the food goes to good purpose.

We'll have to wait for the IME to clarify where its figures are from and whether they're intended to include food used usefully but not for human consumption. As things stand, the story might not be as simple as it looks.

Update

We've now heard back from the IME about its headline figures. Some of the article has been corrected to account for this.

The picture is more complex than it first looks. IME explained that their estimate was based on extensive research into the general literature around international food waste, combined with the knowledge and experience of IME's own members. This research was led by their lead fellow with considerable experience in the field.

To this extent, the two reports cited weren't intended to provide a comprehensive evidence base for the claim (not least due to the wide range of estimates in the field given difficulties acquiring definitive data and different assumptions). They represent selected further reading on the subject.

A lot of work is cited in the report so it would be difficult to actually get a comprehensive range of estimates to back up the headline figures. The selected reading indicates that at least some of this research may be based on a wider definition of waste such as that discussed in this article, but we can't say much more than this.