Call it “your brain on ice cream.” Difficulty getting back on track after a high fat splurge may be at least partially due to changes in brain composition and chemistry brought on by certain fats. A new study from the UT Southwestern Medical Center suggests that certain fats affect appetite by sending messages to body cells, telling them to ignore appetite-suppressing signals from insulin and leptin. In test animals, the effect lasted several days, resulting in higher calorie intakes. If this is an indication of how these fats behave in humans, it provides another reason to limit concentrated food sources, especially for people prone to insulin resistance and weight gain.
Researchers have known that high fat diets can cause insulin resistance, but it has been less clear how this happens and whether the type of fat plays a role. The brain incorporates fats into its structure, so it seems logical that the types of fats that a person eats would make a difference in how the brain functions.
The research team gave fats to study animals in three ways: by injection directly to the brain, through the carotid artery, or through a stomach tube three times a day. In each case, two types of fat mixtures were studied. One was high in palmitic acid, a highly saturated fatty acid found in high fat dairy foods and meat, and the other was high in oleic acid, which is a major component of olive and grapeseed oils.
While oleic acids did not reduce the ability of leptin and insulin to carry out their functions in body cells, the palmitic acid did not allow these hormones to perform their appetite suppressive function. In short, the study makes a good case for limiting foods like greasy hamburgers, ice cream, and cheese, because they may cause people to eat more by shutting off normal appetite suppressing body chemistry. The good news is that we may be able to set the stage for a trim fit body by building a better brain with healthy fats. With that in mind, you may want to limit the butter burgers and custard shakes. They may end up in your brain before they end up on your hips!