Humanized antibodies, or antigen-binding portions thereof, that preferentially bind acylated ghrelin with respect to unacylated ghrelin, are disclosed. These molecules have high affinity and a slow off rate for acylated ghrelin, and neutralize acylated ghrelin activity. These antibodies, or antigen-binding portions thereof, are useful for neutralizing acylated ghrelin activity, e.g., in a subject suffering from a disorder in which ghrelin activity is detrimental, such as obesity.