Researchers have revealed how obesity is associated with altered opioid neurotransmission in the brain. New research reveals how obesity is associated with altered functioning of brain's opioid system, which is intimately involved in generating pleasurable sensations. The researchers found that obesity was associated with significantly lowered number of opioid receptors in the brain. However, no changes were observed in the dopamine neurotransmitter system, which regulates motivational aspects of eating.