Shopping for produce? Here's a chart with some important info!

[mathematic]

80. This is an interesting topic

Your link says nothing about the WHO so I did some searching. The FAO released a study last year that says 33% of food is lost or wasted. That's probably the study you're thinking of. http://www.fao.org/docrep/014/mb060e/mb060e00.pdf

It's a simplification to say that it's a "distribution" problem. The report breaks down the different stages: agricultural production, postharvest handling and storage, processing, distribution, and consumption.

In wealthy countries consumption is the largest single source of food loss (called "waste" when its done by the consumer).

Distribution is generally small and similar in absolute value everywhere, though fruits and vegetables and animal products see much larger distribution losses than other types of ag products. This has a lot to do with lack of cooling, a problem exacerbated by the hot climates of developing nations.

Unsurprisingly, processing losses are lower in wealthier/industrialized countries as this is improved by factories/processing plant efficiency (which depends on technology and industrialization). Processing losses are losses from making juice from fruit or bread from grains, etc.

Postharvest handling and storage is probably something you intended to include under "distribution". The size of its losses are generally between distribution and processing though it does depend on the ag product. It's also much higher in developing countries, due to lack of transportation, storage, and cooling infrastructure.

The report calls for more study on the topic and I hope there is. I'm curious about how this 33% figure changes over time. While historical data probably doesn't exist, I'm also interested in whether this 33% is an improvement from the past. Industrialization/wealth seems to reduce the transport, processing, and distribution losses but increases the agricultural and consumer losses.