IFNG and major depressive disorder: Our results on cytokine levels in different BMI groups revealed that overweight and obese MDD patients had higher IL-1β and IL-6 levels than their lean individuals.Levels of IFN-γ and TNF-α also appeared to be higher in both overweight and obese patients when compared to lean MDD patients, while TGF-β1 levels appeared to decline as body weight increased.