People with narcolepsy are not only excessively sleepy, but they are also prone to gaining weight. In fact, narcoleptic patients will often pack on pounds even as they eat considerably less than your average person. Now researchers appear to have an answer as to why. It seems a deficiency of the neuropeptide hormone orexin, an ingredient that encourages hunger and wakefulness, may leave them with a lack of energy-burning brown fat.
I do not know why it is so hard for writers to refrain from assigning causality to these studies. The fact there there is less brown fat is not a cause of obesity. It's a side effect.
The reason we make more white fat is because we make too much insulin.
Lowered levels of orexin cause hyperinsulinemia.