If you, or someone you know, gets cranky when hungry you know that 'hanger' is real. Sophie Medling is a professor of nutrition and dietetics at King's College London explains, "When our blood sugars drop, cortisol and adrenaline rise up in our bodies-- our fight or flight hormones. The ones that trigger for hunger are the same ones that trigger for anger and rage and impulsive type behaviors. So that's why you get that sort of same response." A 2014 study found that low blood sugar levels lead to increased aggression in married couples.