A Yale study suggests that strong feelings about food can make it harder to learn new eating habits.
Participants adapted more easily when their preferences were challenged at the start of an experiment.
Researchers say the findings could help inform dietary interventions, but the study did not test long-term changes in eating.
For anyone who has struggled to change their diet, new research offers a possible explanation: existing likes and dislikes can get in the way of learning new associations with food.
The study, published in Communications Psychology, involved 279 participants across independent groups. Researchers found that reinforcing people’s food preferences at the beginning of an experiment made them less flexible when the rules subsequently changed.
“Our pre-existing preferences for food are very strong and hard to change,” said Ifat Levy, a professor of comparative medicine at Yale School of Medicine.
Researchers asked participants to identify four snacks—two they liked and two they disliked. Participants then predicted whether a computer program would award positive or negative points for each snack.
During some rounds, the scoring matched their preferences: favorite foods received positive points and disliked foods received negative points. Other rounds reversed those associations, requiring participants to learn rules that conflicted with their feelings.
The influence of first impressions
The starting condition mattered. People whose preferences were reinforced first had greater difficulty adjusting later. Those who began with conflicting associations showed more flexibility. The researchers also found greater rigidity around liked foods, while associations involving disliked foods were easier to update.
That difference raises a possibility for dietary changes: introducing a less-favored food might be easier than giving up a favorite, according to researcher Alex Rich, a former Yale graduate student now at the Massachusetts Institute of Technology. However, the practical meaning of that finding remains uncertain.
The experiment measured predictions about food-related points, rather than actual meals or sustained weight loss. Its findings suggest a potential learning mechanism that future dietary interventions could explore; they do not establish a proven method for changing what people eat.