LEP and obesity due to melanocortin 4 receptor deficiency: Also, hyperleptinaemia is a strong indicator of LR.11 Ageing, disease such as diabetes and neurodegenerative disorders, and excessive exposure to saturated fats and refined sugars (eg, triglycerides and fructose) have been associated with dysfunctional leptin transport into the brain.12–15 On the other hand, obesity has been initially associated with a period of central leptin hypersensitivity, followed by a phase of central LR.12, 16