LEP and major depressive disorder: Third, as research indicates that body fat and leptin are positively correlated30, it is imperative to note that MDD patients in our sample had a higher BMI than HC that also positively scaled with leptin levels; however, within our MDD group, BMI was not significantly related with insula and putamen activation during reward anticipation and did not account for the negative correlation between leptin and reward-related brain activation.