Western diets rich in fat and sugar promote excess calorie intake and weight gain; however, the underlying mechanisms are unclear. Despite a well-documented association between obesity and altered brain dopamine function, it remains elusive whether these alterations are 1. Pre-existing, increasing the individual susceptibility to weight gain, 2. Secondary to obesity, or 3. directly attributable to repeated exposure to a Western diet.
Researchers at the Max Planck Institute for Metabolism Research in Cologne and the CECAD Cluster of Excellence for Aging Research at the University of Cologne, in collaboration with Yale University, have now shown that foods with a high fat and sugar content change our brain.
The researchers offered one group of volunteers, in addition to their regular diet, a little pudding with a lot of fat and sugar every day for eight weeks to test this theory. The custard served to the opposing group had the same calories but less fat. Brain activity was monitored in the volunteer both before and after the eight weeks.
Marc Tittgemeyer, who led the study, said, “The brain’s response to high-fat and high-sugar foods was greatly increased in the group that ate the high-sugar and high-fat pudding after eight weeks. This particularly activated the dopaminergic system, the region in the brain responsible for motivation and reward.”
“Our measurements of brain activity showed that the brain rewires itself through consuming chips and co. It subconsciously learns to prefer rewarding food. Through these changes in the brain, we will unconsciously always prefer the foods that contain a lot of fat and sugar.”
The test subjects did not acquire any more weight than the test subjects in the control group during the study period, and their blood values—such as blood sugar or cholesterol—did not change either. According to the researchers, the preference for sweet foods is expected to persist when the study is over.
Marc Tittgemeyer said, “New connections are made in the brain, and they don’t dissolve so quickly. After all, the whole point of learning is that once you learn something, you don’t forget it so quickly.”
- Sharmili Edwin Thanarajah, Alexandra G. DiFeliceantonio, Kerstin Albus. Habitual daily intake of a sweet and fatty snack modulates reward processing in humans. Cell Metabolism. DOI: 10.1016/j.cmet.2023.02.015