Everyone knows that an apple per day is a more healthful option than a donut and yet, given the choice, many people would still choose the donut. A new study has revealed that food choices could be down to the associations that we make with food-related stimuli.

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Researchers explain why the urge to eat a donut is mightier than the urge to eat an apple — even though the apple is the more healthful option.

Aukje Verhoeven, Sanne de Wit, and Poppy Watson, all psychologists at the University of Amsterdam in the Netherlands, conducted the research.

Their findings were published in the journal Appetite.

The consumption of unhealthful foods is on the rise around the world, which is contributing to the more than 1.9 billion adults who are overweight globally.

Among children in the United States, more than 27 percent of calories each day come from snacks, including salted snacks, candy, desserts, and sweetened beverages. This could have hazardous consequences for their health.

Learned cues affect food choices

Government initiatives have focused on making people more aware of the adverse effects of eating unhealthfully. However, most people fail to adhere to the recommended food guidelines, and eating behaviors often remain unchanged.

Though it is not clear why informational interventions do not work, evidence suggests that food-related stimuli in the environment may play a role in triggering unhealthful eating habits.

"Health warnings often make people want to choose healthier food products, yet many still end up picking unhealthy food products," explains Verhoeven. "We suspected this might partly be due to the fact that people learn to associate specific cues in their environment with certain food choices."

For example, seeing a large "M" sign in the environment has been linked to reward, such as eating a cheeseburger, which then prompts a craving and could trigger a trip to the restaurant.

These learned associations between cues and outcomes have a significant effect on the foods that people choose to consume.

"Unhealthy choices are therefore automatically activated by learned associations, making health warnings, which focus on conscious choices, ineffective," Verhoeven adds.

Warnings ineffective in the presence of cues

Verhoeven and team aimed to investigate whether the presence of food-related stimuli and the behaviors they provoke are the reason why health warnings have a limited effect on eating choices.

The participants learned to press keys for two food rewards and learned associations between the stimuli and the reward. Information was displayed on the health risks of one of the two rewards, then participants had to choose between the two food options.

The investigators expected that when no stimuli were presented, the participants would choose the food that they thought was more healthful. But in contrast, they hypothesized that with stimuli, the participants would select the associated reward, regardless of whether it was the healthful or unhealthful choice.

"Health warnings for healthy food choices only seem to be effective in an environment where no food cues are present," says Verhoeven.

"Whenever stimuli are present which people have come to associate with certain snacks," she adds, "they choose the accompanying (unhealthy) food product, even when they know it is unhealthy or aren't really craving that food product."

"It didn't matter whether we alerted the subjects before or after they learned the associations with food cues."

Limiting environmental stimuli

Health warnings seem to change a person's attitude and intention, but they do not always result in behavioral changes. The authors say that there is an urgent need for strategies to be developed that prevent unhealthful associations or that reduce their influence.

Verhoeven and her colleagues suggest that one strategy would be to complement health warnings with adding the health risks onto the products themselves to boost healthful food choices. The study authors continue:

"A more promising strategy suggested by the present study is to promote healthy choices by significantly limiting the availability of environmental stimuli that are associated with unhealthy food outcomes, such as certain commercials, especially those focused at vulnerable populations such as children."

Healthful choices could be promoted by making the unhealthful ones less visible, the researchers recommend. This might include placing healthful food options near the cash desk while moving unhealthful snacks to a place that is less noticeable.