Posted: March 17, 2022

Food waste affects more than Americans' wallets; it also has implications for their health and the environment.

Do you periodically purge putrid parsley, rancid yogurt, and stale leftover pizza from your refrigerator, tossing it in the trash and perhaps feeling guilty about the waste? You're not alone. According to Edward Jaenicke, professor of agricultural economics, American households throw away, on average, almost a third of the food they acquire, an amount that is worth about $240 billion annually.

"Divided among the nearly 128.6 million U.S. households, this waste could be costing the average household about $1,866 per year," he says. "That's enough to cover the typical American household's combined annual expenditures on gasoline and public transportation."

This inefficiency in the food economy has implications for health, food security, food marketing, and climate change, says Jaenicke, who recently published a paper in the American Journal of Agricultural Economics on the topic.

"Our new study was the first to identify and analyze the level of food waste for individual households, which has been nearly impossible to estimate because comprehensive, current data on uneaten food at the household level do not exist," he says.

In lieu of rummaging through people's trash cans, Jaenicke and his former graduate student Yang Yu studied household food waste by creating a model to analyze data from the U.S. Department of Agriculture's National Household Food Acquisition and Purchase Survey, known as FoodAPS, in a new way. In fact, Jaenicke and his colleagues are experts at using large national datasets to glean information about household behaviors that otherwise would be tricky to obtain.

A Model for Estimating Food Waste

To overcome the difficulty in estimating the amounts of food wasted in individual households, Jaenicke and Yu borrowed methodology from the fields of production economics--which models the production function of transforming inputs into outputs--and nutritional science, by which a person's height, weight, gender, and age can be used to calculate metabolic energy requirements to maintain body weight.

In this novel approach, Jaenicke and Yu, now an assistant professor of agricultural economics at Montana State University, analyzed data primarily from 4,000 households that participated in FoodAPS. Food-acquisition data from this survey were treated as the "input."

FoodAPS also collected biological measures of participants, enabling the researchers to apply formulas from nutritional science to determine basal metabolic rates and calculate the energy required for household members to maintain body weight, which is the "output." The difference between the amount of food acquired and the amount needed to maintain body weight represents the production inefficiency in the model, which translates to uneaten, and therefore wasted, food.

"Based on our estimation, the average American household wastes 31.9 percent of the food it acquires," Jaenicke says. "More than two-thirds of households in our study have food-waste estimates of between 20 and 50 percent. However, even the least wasteful household wastes 8.7 percent of the food it acquires. Our findings are consistent with previous studies, which have shown that 30 to 40 percent of the total food supply in the United States goes uneaten--and that means that resources used to produce the uneaten food, including land, energy, water, and labor, are wasted as well."

Diving Deeper

The researchers next aimed to understand how various household characteristics, such as income and household size, influenced differences in food waste among households. Analyzing demographic data collected as part of the survey, they found, for example, that higher-income households generate more waste. Those with healthier diets that include more perishable fruits and vegetables also waste more food, the study suggested.

"It's possible that programs encouraging healthy diets may unintentionally lead to more waste," says Jaenicke. "That may be something to think about from a policy perspective--how can we fine-tune these programs to reduce potential waste."

Household types associated with less food waste include those with greater food insecurity--especially those that participate in the federal SNAP food assistance program, previously known as "food stamps"--and those with a larger number of members. "People in larger households have more meal-management options," Jaenicke explains. "More people means leftover food is more likely to be eaten."

In addition, some grocery items are sold in sizes that may influence waste, he says. "A household of two may not eat an entire head of cauliflower, so some could be wasted, whereas a larger household is more likely to eat all of it, perhaps at a single meal."

Among other households with lower levels of waste are those who use a shopping list when visiting the supermarket and those who must travel farther to reach their primary grocery store. "This suggests that planning and food management are factors that influence the amount of wasted food," Jaenicke says.

Beyond the economic and nutritional implications, reducing food waste could be a factor in minimizing the effects of climate change. Previous studies have shown that throughout its life cycle, discarded food is a major source of greenhouse gas emissions, the researchers pointed out. "According to the UN Food and Agriculture Organization, food waste is responsible for about 3.3 gigatons of greenhouse gas annually, which would be, if regarded as a country, the third-largest emitter of carbon after the U.S. and China," says Jaenicke.

The researchers suggested that this study can help fill the need for comprehensive food-waste estimates at the household level that can be generalized to a wide range of household groups. "While the precise measurement of food waste is important, it may be equally important to investigate further how household-specific factors influence how much food is wasted," says Jaenicke. "We hope our methodology provides a new lens through which to analyze individual household food waste."

Searching for Solutions

Beyond the myriad things consumers can do to cut their own waste, such as planning meals that overlap in the ingredients they use, what else can be done to reduce food waste? In 2010, the New York City Board of Health decided to lengthen the sell-by dates of milk products. Previously, the New York City Code required all milk products to be sold within nine days after pasteurization. The new policy left the sell-by dates to be determined by milk manufacturers and processors, effectively increasing the shelf life of milk to about 14 to 15 days.

"Sell-by dates play a key role in determining the consumption of perishable food," says Jaenicke. "Unfortunately, consumers often misinterpret 'sell-by' dates as 'safe-until' dates, which often leads to food being tossed earlier than necessary. In fact, sell-by dates generally do not refer to food safety concerns but merely serve as an indicator of 'best quality.'"

To analyze the effects on food waste of New York City's policy change, Jaenicke and Yu constructed models on the sales volumes reported in the Nielsen Retail Scanner data, for a period of 12 months before and after the policy change. They also assessed the policy's impact at the household level by performing estimations on household monthly purchase volumes using the Nielsen Consumer Panel Data.

"Our results show that extending the sell-by dates of New York City's milk products reduced food waste by at least 10 percent and that consumers actually drank more milk while spending less money on milk products," says Jaenicke. "This work supports the assertion made by the City's Board of Health, which stated that the previous nine-day rule led to unnecessary disposal of milk without imposing additional health and food safety risks to consumers."

Jaenicke says he hopes his research will help policymakers and food industry managers who oversee date-labeling programs. More importantly, however, he aims to help consumers save money and stay healthy.

"We see a clear link between food waste and levels of dietary healthfulness," says Jaenicke. "In the case of the milk sell-by dates, reduced waste went hand in hand with an increase in milk consumption, yet our other research showed that efforts to purchase healthier foods may lead to more waste. These nuanced findings may be crucially important for policies aimed at simultaneously reducing food waste and improving diets."

How Can I Cut My Waste?

You can reduce the amount of food you waste with these tips from Penn State Extension:

  • Look for recipe ideas that use up ingredients you already have at home.
  • Plan meals for the week that overlap in the ingredients they use. For example, a roast chicken on Sunday, followed by chicken soup on Monday and chicken salad sandwiches on Tuesday.
  • Use overripe fruit in a fruit smoothie.
  • Half a bag of spinach added to leftover noodles with your favorite sauce can make for a quick, delicious meal.
  • Rather than buying a new ingredient for a recipe, check to see if you might have a suitable substitute at home. For example, walnuts can be swapped for pecans, and plain Greek yogurt works well as a replacement for sour cream.
  • To extend the shelf life and keep perishable food safe to eat, set your refrigerator to 38 degrees Fahrenheit.
  • Stop peeling carrots, parsnips, cucumbers, and other vegetables.
  • If you find yourself with leftovers, eat or freeze them within just a few days.
  • Donate safe food to your local food bank.
  • Purée herbs and olive oil and freeze in ice cube trays to use later as pesto or other herb sauces.
  • Use sour milk to make pancakes or other baked goods that call for buttermilk.
  • Save Parmesan rinds in the freezer and add them to soup to enhance the flavor.
  • Toss stale bread into the blender and freeze the breadcrumbs as a topping for pasta or gratins, a coating for pan-fried cutlets, or in meatballs or meatloaf.

-- Chuck Gill and Sara LaJeunesse