Study: American food waste rising along with obesity rates

Researchers with the National Institutes of Health find a strong relationship between Americans’ growing waistlines and the growing waste of food and the energy to produce that unused food. Could addressing the oversupply of food energy in the U.S. help curb the obesity epidemic?

Americans throw away over 40 percent of all available food each year. Production of that wasted food accounts for more than one-quarter of the U.S.’s total annual freshwater consumption and equates to 300 million barrels of oil, according to a study by researchers at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

“It’s comin’ on Christmas...” goes the song, and we shall all soon be sitting down to what is traditionally one of the biggest eating sprees of the year and probably one of the most wasteful, too. In that context, “The Progressive Increase of Food Waste in America and Its Environmental Impact,” a study published in PloS One, makes edifying reading.

“Recent spikes in food prices have led to increasing concern about global food shortages and the apparent need to increase agricultural production,” wrote the authors, adding “Surprisingly little discussion has been devoted to the issue of food waste.”

The study confirms previous papers on this subject, many of which have estimated food waste figures in developed countries at some 30 to 40 percent. One of the reasons for these figures is said to be the increasing quantity of cheap and readily available food.

Underdeveloped countries were found to throw away food, too. However, that is due less to the throwing away of excess food than it is to harvest loss and other factors at the beginning of the food chain –- the production and transformation stage. Figures in this area are less reliable, varying between 10 and 60 percent, depending on the type of agricultural product or harvest.

Physiologists at the NIDDK used a system consisting of calculations based on the quantity of food available, national food and calorific intake and the average weight of Americans in reaching their conclusions.

In 1970 each American absorbed an average of 2,100 calories per day for the 3,000 calories of food available. Today those figures are 2,300 and 3,800 respectively, and the average weight of an American has increased by 10 kg (about 22 lbs.). This signifies that whereas just less than 30 percent of food was thrown away in 1970, today’s figure is 40 percent.

Much of the waste in richer countries occurs towards the end of the food chain –- the consumption stage. The American food distribution sector rejects some of its product for aesthetic reasons, and strict sell-by legislation accounts for more. Another major waste source is major catering facilities such as company and municipal canteens. Households are also responsible for non-negligible quantities of thrown-away food.

Using the assumption that agriculture uses around 70 percent of freshwater supplies, the study calculates that more than 25 percent of all freshwater use is dedicated to what will become wasted food.

Also, the amount of fossil fuel needed to produce 1kcal (kilocalorie –- the most commonly used food energy unit measurement) of food before processing and transportation is estimated to be 3kcals. That figure represents about 300 million barrels of oil per year.

Another finding was that the amount of food waste rotting in landfills produces substantial amounts of methane, a gas with 25 times the global warming potential of CO², which is what all that wasted food would have produced had it been eaten by humans.

The researchers speculate that the increase in food waste may be driven by increased food availability and marketing, and people just cannot eat all the food which is being produced.

The study authors offered a possible solution to the problem. “Thus, addressing the oversupply of food energy in the US may help curb the obesity epidemic as well as decrease food waste, which has profound environmental consequences.”

Citation: Hall KD, Guo J, Dore M, Chow CC (2009) The Progressive Increase of Food Waste in America and Its Environmental Impact. PLoS ONE 4(11): e7940. doi:10.1371/journal.pone.0007940