Some studies suggest that iron deficiency may be a trigger in the development of obesity and type 2 diabetes, impairing thermogenesis due to reduced binding of thyroid hormones to nuclear receptors and triggering impaired utilization of norepinephrine in tissues together with an impaired distribution of cortisol, which is translated to a reduced reactivity to stress [12]. Here, TG is linked to obesity due to melanocortin 4 receptor deficiency.