We know not to do the grocery shopping when we are hungry, as such timing is likely to ensure a whole lot of junk food makes it into the trolley. But research shows that it isn’t just food related choices that could suffer when we are peckish. It turns out we are best to avoid making decisions on an empty stomach.
This fascinating little titbit of wisdom all comes down to the actions of a hormone called Ghrelin. It is produced in the stomach, released before meals and known to increase appetite .
The only problem is that in a new study conducted on rats, the hormone was shown to have a negative bearing on decision-making and impulse control. “For the first time, we have been able to show that increasing ghrelin to levels that are seen prior to meals or during fasting causes the brain to act impulsively and also affects the ability to make rational decisions,” said Karolina Skibicka (one of the study’s authors) .”
As part of the study, rats were given a series of three tests measuring their ability to inhibit a behavioural response. Two of the tests measured the rats’ ability to restrain a response and one of them measured their ability to delay gratification. All of these are skills that can indeed be trained in rats. However, when they were under the influence of the hunger hormone, things got interesting. Researchers measured these responses, along with dopamine and gene expression associated with impulsivity .
The research yielded some fascinating results. It was quite clear that impulse control and the ability to delay gratification suffered significantly.
“Our results showed that restricting ghrelin effects to the ventral tegmental area, the part of the brain that is a crucial component of the reward system, was sufficient to make the rats more impulsive. Importantly, when we blocked ghrelin, the impulsive behavior was greatly reduced,” says Karolina Skibicka. Even a short period of fasting, a more natural way of increasing the release of ghrelin, increased impulsive behavior. ”
Interestingly, the gene expression issue flagged a couple of potential problems. It found that increased ghrelin levels could cause long-term genetic changes in some brain circuits (those linked with impulsivity and decision making) . “A ghrelin injection into the brain that resulted in impulsive behaviour in rats, caused the same type of changes in dopamine-related genes and enzymes as can be seen in ADHD and OCD .
This lead researchers to speculate that ghrelin receptors could possibly be a target for future treatment of psychiatric disorders characterised by impulse control issues .
It will be interesting to see where this line of investigation leads! Hunger pangs exist for a reason and hence its unrealistic for us to avoid ghrelin at all. Until research points us in a clear direction for the therapeutic applications of this study, we have but one take-away: hunger makes you impulsive and clouds decision-making.
Don’t make decisions on an empty stomach.
 University of Gothenburg. “Hormones that are released during hunger affect decision making.” ScienceDaily. ScienceDaily, 9 May 2016. www.sciencedaily.com/releases/2016/05/160509085807.htm
 Anderberg R, Hansson C, Fenander M, Richard A, Dickson S, Nissbrandt H, Bergquist F and Skibicka K (2016), “The Stomach-Derived Hormone Ghrelin Increases Impulsive Behavior,” Neuropsychopharmacology (2016) 41, 1199–1209; doi:10.1038/npp.2015.297; published online 21 October 2015 http://www.nature.com/npp/journal/v41/n5/full/npp2015297a.html