New research suggests that when people are hungry, they focus more on the tastiness of food and tend to ignore nutritional information, which may contribute to poor dietary decisions.

The study, published as a revised Reviewed Preprint in eLife, is described as important by the eLife editors. They say the well-designed experiments—including choice behavior, eye-tracking and state-of-the-art computational modeling—yield compelling evidence to support the conclusion that people who are hungry prioritize tastiness over healthiness in their food choices.

Despite existing public health initiatives, the prevalence of obesity has been steadily increasing in many countries. According to the World Health Organization, worldwide adult obesity has more than doubled since 1990, and adolescent obesity has quadrupled. In 2022, 2.5 billion adults were overweight, and of these, 890 million people were living with obesity—which can significantly increase the risk of developing serious health conditions, including type 2 diabetes, cardiovascular diseases and certain types of cancer.

Throughout a single day, we make several decisions about what to eat, and these choices are largely influenced by our environment. For example, it has been previously demonstrated that nutritional scores on food options can increase the likelihood of healthy choices. On the other hand, it has been shown that a hungry decision-maker is more likely to make unhealthy choices.

"A preference for energy-dense foods is likely an evolutionary adaptation to ensure survival under conditions of scarcity. However, as high-caloric food options have become more easily available and affordable, this neurobiological mechanism to reward the consumption of calorie-dense foods is likely a contributing factor to the global surge in obesity rates," says co-author Jennifer March, a Ph.D. student in the Department of Psychology and Hamburg Center of Neuroscience, University of Hamburg, Germany.

"While we know that hunger can lead to more unhealthy food choices, we set out to better understand the cognitive mechanisms underlying this, by investigating the effect of hunger on attention and valuation processes in dietary choices."

March served as the lead author of the paper alongside Sebastian Gluth, professor and Head of Cognitive Modeling & Decision Neuroscience in the Department of Psychology and Hamburg Center of Neuroscience, University of Hamburg.

March and Gluth recruited 70 adults from the University of Hamburg and surrounding area and asked them to complete a food choice experiment in both hungry and satiated states. In both conditions, participants underwent an overnight fast. In the satiated condition, they received a protein shake the next morning at the start of the study, which matched their daily caloric needs. In the hungry condition, participants underwent an overnight fast. Participants also underwent a brief survey in order to define which foods they considered tasty, and how caloric they perceived them to be.

Using eye-tracking technology, they recorded where participants focused their attention when deciding between a healthier but less tasty option, and a tastier but less healthy one. Each food was labeled with a Nutri-Score—a standardized nutritional rating. To analyze how each participant's attention affected their food choices, the team utilized an advanced decision-making model known as the multi-attribute attentional drift diffusion model.

Although all participants showed a preference for tasty over the healthier options, regardless of hunger-state, the results confirmed that hunger significantly amplified this preference. This aligns with previous research that says that hunger increases the perceived reward of calorie-dense foods. However, this work goes a step further by demonstrating that this effect is driven by visual attention patterns and the way information is weighted in the brain's decision-making process.

In the hungry condition, participants focused more on the visual appeal of food options and less on the Nutri-Score compared to the satiated condition. They also made their choice more quickly when hungry. The author's computational modeling revealed a two-fold effect: hunger increased the importance of taste in decision-making while also making participants less likely to factor in health information. In fact, hungry participants seemed to effectively ignore the Nutri-Score unless it was actively fixated on.

This suggests that simply displaying nutritional information labels may not be sufficient to counteract hunger-driven food choices. The researchers suggest that interventions designed to promote healthy eating should focus on making health information more visually prominent or directing attention toward it.

The study focuses on immediate food choices in a controlled laboratory setting. Future research could explore how these findings translate to real-world settings, such as grocery stores or restaurants, where environmental cues and marketing tactics may further influence decision-making.

"The key takeaway is that hunger doesn't just make unhealthy but tasty food seem more appealing, it also alters the decision-making process itself by shifting what information the brain prioritizes," says Gluth.

"This has important implications for public health. If we can design interventions that help direct attention towards health information, we may be able to counteract the biological drive to choose calorie-dense foods when hungry and promote healthier eating habits."