Galanin is a protein found in the brain  In an experiment, rats that consistently chose to eat fatty foods when offered a choice between lean and fatty foods were found to have significantly higher concentrations of galanin in their brains than did rats that consistently chose lean over fatty foods
These facts strongly support the conclusion that galanin causes rats to crave fatty foods
Rats that metabolize fat less efficiently than do other rats develop high concentrations of galanin in their brains.