If you're a fast foodie, you've probably noticed that regularly eating junk food has an undeniable effect on how you look, as well as the number on the scale.It all involves a proteinBut according to a 2019 study conducted by Yale University in the United States, junk food could affect the brain long before you notice its effects on your body.According to scientists, it only takes three days of consuming large amounts of fat and carbohydrates for the brain to be affected. The culprit: a protein called UCP2 that causes inflammation of the hypothalamus, which plays a vital role in regulating your appetite and managing fear.How diet influences brain healthIn the lab, researchers noted that the activation of this protein stimulates animals' appetite and increases their risk of being obese. But when they blocked this mechanism and removed the protein, the animals on a high-fat diet ate less and were more resistant to weight gain. Lead author of this study Dr. Sabrina Diano explained:There are specific brain mechanisms that get activated when we expose ourselves to a specific type of food.And said mechanisms have very clear consequences on the body. Besides expanding our knowledge of nutrition, it is Dr Diano's hope that her research will help us gain a better understanding of things like the mechanisms behind Alzheimer's disease.