Samples from the morbidly obese undergoing weight loss surgery showed that melanin - a pigment giving skin and hair their distinctive colour - was being produced in their fat tissue. Melanin production has never before been identified in fat tissue.

The researchers believe the antioxidant, having anti-inflammatory properties, could be the body's natural defence against obesity-related conditions such as type-2 diabetes, coronary heart disease, fatty liver disease, polycystic ovary syndrome and some cancers.

They explained that, stockpiling extra calories is difficult even for specialized fat cells; having too much lipid molecules takes its toll on the fat cells, producing oxidative stress. It's not unthinkable that these cells would adapt and produce melanin as a form of self-protection. As a side benefit, melanin may suppress inflammatory properties of the extra pounds of the fat.

A larger study is needed in order to confirm the role that the body's production of this compound plays in fat tissue. However, the discovery suggests that melanin-based therapies may one day be used to reduce the incidence of chronic diseases among the morbidly obese.