Over the course of the experiment, the sugar drastically lowered the “availability” of the pig’s opioid and dopamine receptors, effectively “dampening down” their response to these “rushes” of happy hormones. This reaction is also seen in the brains of humans who are addicted to cocaine, although the researchers weren’t expecting it to happen quite so quickly in this instance.
"After just 12 days of sugar intake, we could see major changes in the brain's dopamine and opioid systems,” Michael Winterdahl, the study’s author and an associate professor at the Department of Clinical Medicine at Aarhus University in Denmark said in a statement. “In fact, the opioid system, which is that part of the brain's chemistry that is associated with well-being and pleasure, was already activated after the very first intake.”
Of course, the scientists can’t guarantee these results would be replicated in humans, but it does make a pretty compelling case as to why we should skip the sweet stuff.
"If sugar can change the brain's reward system after only twelve days, as we saw in the case of the pigs, you can imagine that natural stimuli such as learning or social interaction are pushed into the background and replaced by sugar and/or other 'artificial' stimuli,” Winterdahl added.
A good enough reason as any, we say.