LEP and Obesity: However, some researchers reported that concentration of leptin in blood is related to other tastes/oral sensations, apart from sweet: it was observed that regular weight men sensitive for the bitter taste elicited by PTC (phenylthiocarbamide) presented higher plasma leptin levels, comparatively to the nonsensitive pairs [18]; one study reported that, in a low grade inflammation related to obesity, alterations in orosensory perception of oleic acid are related to circulatory levels of leptin [19].