In addition to the effect of sugar rich meals on dopamine
release and receptor activity, recent research has uncovered
the effects of sugar intake on the endorphin system. To begin
with, injection of mu agonists into the nucleus accumbens
increases the intake of palatable foods rich in sugar and fat
(Kelley et al. 2002; Zhang, Gosnell & Kelley 1998). In addition,
opioid antagonists decrease the ingestion of sweet
food and decrease the feed time of palatable and preferred
foods (Kelley et al. 2002).