Consumers around the world may be wasting more than twice as much food as commonly believed, according to a study.
The Food and Agriculture Organization of the United Nations (FAO) estimated that in 2005, one third of all food available for human consumption was wasted, researchers from Wageningen University and Research in the Netherlands noted.
This figure has continued to serve as reference for the extent of global food waste, they said.
However, the FAO methodology does not factor in consumer behaviour regarding food wastage, and considers food supply alone in determining the extent of food waste, the researchers said.
The study, published in the journal PLOS ONE, is the first to investigate if and how consumer affluence may affect food waste, they said.
"Novel research using energy requirement and consumer affluence data shows that consumers waste more than twice as much food as is commonly believed," said Monika van den Bos Verma from Wageningen University and Research.
"It provides a new globally comparable base against which one can measure progress on the international food waste target, and suggests a threshold level of consumer affluence around which to launch intervention policies to prevent food waste from becoming a big problem," Verma said.
Using a human metabolism model and data from FAO, the World Bank, and the World Health Organization (WHO, the researchers quantified the relationship between food waste and consumer affluence.
Using this model, they created an international dataset providing estimates of global as well as country specific food waste.
The researchers found that once consumer affluence reaches a spending threshold of about USD 6.70 per day per capita, consumer food waste starts to rise.
The wastage increases rapidly with rising affluence at first, and then at much slower rates at higher levels of affluence, they said.
The study also showed that FAO's estimates of consumer food waste may be too low.
While FAO estimated food waste to be 214 kilo calories per day (Kcal/day) per capita in 2015, the new model estimated food waste as 527 Kcal/day per capita for the same year.
This work relies on the accuracy of FAO's data, which may not always be complete.
The researchers also noted there are many consumer attributes that may affect food wastage beyond affluence.
However, the new study suggests that to achieve low global food waste, a joint focus on reducing high food waste levels in high income countries, and preventing waste levels from rising rapidly in lower-middle income countries -- where affluence is increasing—may be needed.
The researchers believe that the method behind this study can be used as a basis to introduce the affluence elasticity of waste as a new concept in future models.
It may also help better understand and assess current food waste magnitudes, and help measure global progress in reducing food waste, they said.