Foods like burgers, fries and milkshakes taste good to us because they are manufactured to be psychologically rewarding and appealing to our palates. Their appeal stems from the tasty additives they contain — like fat, salt, sugar and refined carbohydrates. You could even say people become addicted to these foods.

This compulsion for processed foods can lead to several serious health problems. Eating too many processed foods, while not getting enough unprocessed, more nutritious foods like whole grains, fresh fruits and vegetables, increases the risk of developing chronic conditions such as cardiovascular disease, type 2 diabetes and certain cancers.

Can people come to believe that eating an apple can make them feel just as happy as eating an apple pie?

It's important to look at the psychology behind the reasons people make the food choices they do because such poor eating habits are so common worldwide. Addictive substances can bring on compulsive use and strong cravings, Jenna Cummings, the lead author of a study from the University of Michigan and the University of Liverpool in the United Kingdom told TheDoctor. Evidence from rodent and human studies suggests that processed foods can elicit the same response, sometimes called food addiction.

“Many people think eating highly processed foods such as cheeseburgers and French fries will make them happier,” Cummings points out. But in fact, the opposite may be true — studies have linked fried foods, especially French fries, to depression.

Almost 37 percent of the over 700 participants in the current study had food addiction. Participants were randomly assigned to watch 15-second video advertisements for highly processed foods, 15-second advertisements for minimally processed foods or ads for both types of foods. A fourth control group watched advertisements for smartphones. Then they completed questionnaires about their feelings, beliefs and behaviors about what they had seen.

The researchers found that among those with fewer symptoms of food addiction, ads for highly processed foods raised expectations of feeling positive emotions while eating these foods. Participants with few symptoms of food addiction probably enrolled in the study without strong expectations about how highly processed foods might affect their emotions, leaving more room for their beliefs and expectations to change, said Cummings, a lecturer in psychology at the University of Liverpool.

Most advertisements had an insignificant effect on food-related emotional expectations. Cummings was surprised that ads for minimally processed foods had no effect on anticipating positive emotions while eating them, saying, “Advertising nutritious foods may not be enough to get people to eat them.”

Going forward, more research is needed to determine what role additives may play in the addictive nature of processed foods. It is possible that people develop a tolerance to these additives, leading them to need to eat more of these foods. People may also experience withdrawal — physical and psychological changes in response to eating fewer processed foods — when they reduce their consumption.

Another question Cummings is planning to investigate is how much a person’s expectations about the foods they are eating can change, and if these expectations can change through means other than advertisements: “Can people believe that eating an apple can make them feel just as happy as eating an apple pie?”

Another approach might be to try to change the marketing messages surrounding fast foods. As Cummings pointed out, “Regulating fast-food advertisements and changing beliefs about how highly processed foods affect emotions could help people choose more nutritious foods.”

The study is published in the Journal of Health Psychology.