LEP and Obesity: Pannacciulli et al. (2007) studied the relation between plasma leptin concentrations and human brain structure in a group of lean and obese normal participants and did not find any positive or negative associations between plasma leptin and the volume of the white matter. However, it is widely noticed that obesity patients are associated with abnormally increase of leptin levels. This increase is believed to be cause by the reduced ability of leptin to suppress appetite and weight gain, hence, developing leptin resistance (Maffei et al., 1995; Zhou and Rui, 2013).