Ghrelin is a hormone released by the lining of the stomach that promotes feeding behavior. Decreasing ghrelin levels could potentially help combat obesity -- in fact, a vaccine that lowers ghrelin levels in order to reduce appetite is being studied as a treatment for obesity. However, many people eat as a way to relieve stress. If low ghrelin levels increase stress, its effectiveness as a treatment for obesity may be reduced. In a new study, researchers show that mice with no ghrelin are more anxious after stress, but that administration of endogenous ghrelin prevents the over-anxious response.