Sources of Food Waste

Which types of food are responsible for the most food waste?  This was a question I attempted to answer with my monthly Food Demand Survey (FooDS) back in January.  There we found that people stated that they tend to waste the most fresh fruits and vegetables followed by bread and bakery products followed by dairy followed by meat.  

I recently ran across this paper by Heller and Keoleian in the Journal of Industrial Ecology.  Their answer to this question is: it depends how you measure it.  

The following figure is from their paper.  The pie chart in the upper left-hand corner is waste measured per pound of food produced.  This measure matches up quite well with my consumer survey: fruits and vegetables are the highest waste categories representing 19%+14%=33% of all the pounds wasted. By this measure, meat represents a small fraction of the total waste.

However, fruits and vegetables don't provide many calories.  The panel on the upper right-hand side of the chart is food waste measured per calorie of food produced.  Now, fats ad oils are the biggest culprit and followed by grains.  By this measure, fruits and vegetables and most meat products are only a small fraction of waste.  

The last pie-chart on the bottom of the figure measures waste per unit of greenhouse gas emitted.  Because beef is a ruminant and produces methane during digestion, it is a relatively large contributor of greenhouse gasses.  As a consequence, when measured in terms of greenhouse gases, beef, veal, and lamb appear as the biggest contributors of food waste followed by dairy.  

So, which measure is the "right one"?  I suppose that depends on whether you're most concerned about lost food pounds, lost food calories, or lost greenhouse gases.  

P.S.  The Heller and Keoleian paper has another fascinating and surprising result.  They simulate what would happen if people kept eating the same calories but instead shifted to eating the way suggested in the federal Dietary Guidelines.  The result?  A 12% increase in diet-related greenhouse gas emissions.