Do you know what ghrelin is? Most of us don’t, but now that your interest is peaked, here’s why it’s a good thing to know about. Ghrelin is a stomach hormone that tells your brain when to trigger hunger or fullness signals. Recent research presented at the 2010 annual meeting of the Society of Neuroscience highlighted new findings.Using rats, the researchers found that in addition to moderating normal eating habits, ghrelin also acts on the brain’s pleasure and reward centers—and yes, those are the same areas activated by drugs and sex.Using sugar as the bait, rats pressed a lever hundreds of times to earn a very small amount of sugar. But, rats given ghrelin worked twice as hard for the same treat. When the hormone was blocked in hungry rats (there’s an image I wouldn’t mind blocking), they were less willing to press the lever for the sugar, as if they were actually full. Increasing or decreasing the ghrelin appeared to influence whether the rats preferred environments they associated with sugar consumption.The inference from the study is that ghrelin levels may help explain why people eat when they’re not hungry—that food intake may be driven more in some people by the pleasure they associate with food rather than by their actual hunger.Now, intuitively, we may know that we eat even when we’re not hungry for a number of reasons: we like the taste, we’re bored, we’re stressed, and for some of us, we eat for comfort. If a specific hormone is linked to why we eat for pleasure, we might see that as a “proven scientific excuse” for what might be poor nutritional choices and behaviors. But, we’re not rats and we can make choices, even difficult choices. Still, it’s nice to know that a hormone called ghrelin could actually be making some of those choices more difficult for some of us. Now the question is, knowing this, how can we use this knowledge to begin to change unhealthy eating behaviors? What do you think?