Why we can’t keep our hands off candy bars and co.
Chocolate bars, potato chips and chips - why can’t we just leave them to the left in the supermarket? Researchers at the Max Planck Institute for Metabolic Research in Cologne, Germany, in collaboration with Yale University, have now shown that foods with a high fat and sugar content change our brain: If we regularly eat even small amounts of them, the brain learns to want to continue consuming precisely these foods.
Why do we like unhealthy and fattening foods so much? How does this preference develop in the brain? "Our predisposition to high-fat and high-sugar foods, the so-called Western diet, could be innate or develop as a result of obesity. But we think the brain learns this preference," explains Sharmili Edwin Thanarajah, lead author of the study.
To test this hypothesis, the researchers gave one group of subjects a small pudding containing a lot of fat and sugar per day for eight weeks in addition to their normal diet. The other group received a pudding that contained the same number of calories but less fat. The subjects’ brain activity was measured before and during the eight weeks.
Our brain learns to prefer high-fat snacks
The brain’s response to high-fat and high-sugar foods was greatly increased after eight weeks in the group that ate the sugar- and fat-containing pudding. The dopaminergic system in particular was activated, i.e. the region in the brain responsible for motivation and reward. Our measurements of brain activity have shown that the brain rewires itself through the consumption of chips and co. It subconsciously learns to prefer rewarding food. These changes in the brain mean that we will unconsciously always prefer foods that contain a lot of fat and sugar," explains Marc Tittgemeyer, who led the study.
During the study period, the subjects did not gain any more weight than the subjects in the control group, and their blood values, such as blood sugar or cholesterol, did not change either. However, the researchers assume that the preference for sugary foods will continue after the end of the study. New connections are made in the brain, which are not dissolved so quickly. After all, the whole point of learning is that once you’ve learned something, you don’t forget it so quickly," explains Marc Tittgemeyer.
Sharmili Edwin Thanarajah, Alexandra G. DiFeliceantonio, Kerstin Albus, Bojana Kuzmanovic, Lionel Rigoux, Sandra Iglesias, Ruth Hanßen, Marc Schlamann, Oliver A. Cornely, Jens C. Brüning, Marc Tittgemeyer, Dana M Small - Habitual daily intake of a sweet and fatty snack modulates reward processing in humans, Cell Metabolism, 22 March 2023.