Why are we often more attracted to chocolate cakes or crisps than to broccoli? Industrial foods loaded with sugar, fat and salt, often sold at low prices, have invaded supermarket shelves. However, studies have long shown that a diet that is too sweet and too fatty is suspected of promoting metabolic disorders, obesity, diabetes, cardiovascular diseases, etc.
Food also has many effects on the brain. The teams of Dana Small, from the Yale University School of Medicine (New Haven, United States), and that of Marc Tittgemeyer, from the Max Planck Institute for Metabolism Research in Colognelooked at the ways foods that are too rich can shape it.
A study published on March 22 in the journal Cell Metabolism suggests that eating fatty and sugary foods, even in small amounts and over a short period of time, affects our brain activity and changes our preferences for these same foods. To test this hypothesis, the researchers divided the 49 volunteers – without pathology and of normal weight – into two groups. The first ate a high-fat, high-sugar yogurt twice a day for eight weeks, then a Granola cookie or equivalent, in addition to his normal diet. The other group took over an identical period a yogurt with the same number of calories, but low in fat and sugar. Their brain activity was measured before and during the eight weeks.
Alteration of preferences
At the end of this first phase, the two groups were asked to taste and evaluate sweet desserts that were more or less dense in fat and apple juices that were more or less sweet. Members of the group who ate the higher-fat and higher-sugar yogurts said they no longer liked the low-fat dessert or the low-sweetened apple juice, which showed that the preference for a low-fat or sweetness was altered.
“By combining imaging approaches of brain activity with behavioral tests, the authors demonstrated that repeated exposure to high-fat, sweetened yogurt altered the way so-called ‘reward circuitry’ structures processed information. »comments Serge Luquet, research director at the CNRS, who did not participate in the study. “Even low-level exposure to more fatty and sugary foods decreases cravings for less fatty and sugary foods and changes the way reward structures respond to food cues or perform certain tasks”continues the researcher.
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