A new study from market researchers at the Tuck School of Business at Dartmouth University examines just how hooked Americans are on processed foods packed with salt, sugar, and fat. The study appeared this month in the American Marketing Association’s Journal of Marketing.

Tuck marketing professor Kusum Ailawadi led the study. She and her colleagues set out to map how household income and education affect nutrition and food purchasing. They further examined how food consumption habits changed after a member of the household was diagnosed with diabetes.

“We are interested in actual purchasing behavior,” said Ailawadi in a press release.

Ailawadi is a marketing and research consultant for processed-food makers, such as Proctor & Gamble, and major retailers, including Walmart. The consumer packaged goods (CPG) industry spends billions of dollars annually on consumer studies like this, in order to better understand consumer tastes and trends.

Ailawadi’s study combined four sources of information. The first was a nationwide data set compiled by the market research firm IRI tracking household food purchases from January 2006 through December 2009.

The second source was an annual health survey administered by IRI that included household health status, health-related behaviors, and perceptions about health and diet.

The third was a database that included the nutrient content of packaged food items in 13 food categories. Categories included relatively healthy foods like yogurt and fruit juices, and unhealthy ones, such as processed meats, salty snacks, and cookies.

Finally, the researchers conducted a survey to determine how healthy certain food items were perceived to be, regardless of the ingredients they contained.

The "Health Halo Bias"

In homes where a family member was diagnosed with diabetes, the researchers found a sharp decrease in purchases of foods high in sugar and carbohydrates—yet consumption of salty, fatty foods increased. Sugar reduction came mainly from avoiding high-sugar colas and juices for which low-sugar alternatives are readily available. However, consumption of treats like cookies and ice cream did not decline following a diabetes diagnosis.

Homes with higher levels of education, nutritional interest, and self-control were no better at responding to a diabetes diagnosis than the others, although higher-income households did have improved responses.

In households with highly educated parents who were interested in nutrition, there were fewer purchases of both fatty and sugary foods.

The study also examined the performance of people with "high self-control," as defined by healthy practices, such as regular exercise and infrequent consumption of fast food or late-night snacks. As expected, the self-controllers bought less junk food like sugary cola and potato chips. Yet they offset this benefit by consuming too much of "healthy foods" like yogurt and cereal, leading to a greater overall consumption of calories and sugar.

Consuming more of a food perceived as “healthy” is known as a "health halo bias."

"They're putting more of the 'healthy' foods in their mouths," says Ailawadi. "Once they categorize it as healthy they don't focus on how much of it they're eating."

The Human Cost of Junk Food Addiction

Over the past 30 years, the prevalence of obesity and diabetes has increased at an alarming rate. More than two-thirds of Americans are now considered overweight, and one-third of the adult population—78 million people—is clinically obese, according to 2010 data from the .

Since 1981, the number of Americans diagnosed with diabetes has grown from approximately 5.6 million to more than 26 million, according to a 2011 long-term trend report by the .

The New York Times investigative reporter Michael Moss spent four years learning the secrets of food-industry scientists. In his report, published in February 2013, he wrote: “The public and the food companies have known for decades that sugary, salty, fatty foods are not good for us in the quantities that we consume them.”

Moss documented how the food industry has engineered products that are addictive, convenient, and inexpensive. But why do we keep buying and eating them?

Ailawadi reiterated what the food industry has known for years: "The human palate loves the combination of fat and sugar so they are hard to resist. And it doesn't help that less unhealthy versions of these products are sold at a substantial price premium over the high-fat/high-sugar versions."

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