Water Cooler: Your brain on hunger

It’s common to find yourself a little irritable if you had to miss lunch or if dinner is taking longer than expected, but hunger can affect your brain in a few other ways .

Have you ever been grocery shopping while hungry? Doesn’t it make you want to buy just about everything on the shelf? This common experience has been backed by research that shows we tend to be a bit more impulsive when we’re hungry.

To be clear, this research is in regards to the temporary hunger experienced if you don’t get to eat as soon as you usually do. More serious experiences of regular hunger due to food insecurity come with their own complex psychological and sociological effects.

Many studies have found evidence that our capacity for self-control is lowered when we’re hungry, but what is tricky is you may not always be aware of when hunger is influencing your behavior.

A 2016 study from King’s College London examined 46 adults who were asked to perform computer-based tasks. When the data was compared between adults in a fasted state and adults who recently had eaten, the fasting participants were shown to act with more impulse. When those fasting individuals were asked whether they felt more impulsive in a questionnaire following the test, they did not report themselves as feeling impulsive when hungry.

Whether we recognize it in the moment or not, our biological drive to find food does seem to have an effect on how we behave.

One explanation for this could be found in what is called projection bias, which is the tendency for humans to inaccurately project how they feel now onto a future event.

For example, when you feel like you’re starving, you will likely overestimate how much you will eat in the future just because of how you feel now. Anyone who has said, “My eyes were bigger than my stomach,” likely experienced this phenomenon. On the flip side, you can also experience projection bias if you go shopping when you’re full or in a good mood. In that state, you might feel like making healthier choices and presume you’ll want to eat healthy things in the coming week. If you’ve ever thrown away a mostly full container of wilted greens, projection bias might have affected you.

A 2019 study titled, “Hunger increases delay discounting of food and non-food rewards,” found evidence that hunger may even influence our decision-making by making us more likely to choose a small reward we would receive sooner over waiting for a larger reward later, even if the reward has nothing to do with food. Researchers found a substantial increase in delay discounting for food and about a 25% increase in delay discounting for rewards related to money and music.

One 2010 study titled, “Sweet Future: Fluctuating Blood Glucose Levels Affect Future Discounting,” gave half of its participants regular soda and the other half diet soda. Those who drank the soda with real sugar experienced an increase in blood glucose, which provided a stronger feeling of satiation in the body. Those participants more often chose a “larger but later” monetary reward, whereas those who drank diet and did not experience a big change to their blood glucose engaged in more delay discounting and opted for the “smaller and sooner” reward.

Scientists are still working to understand more about how hunger makes us more impulsive, but as the evidence stands, it’s probably best to not make important life decisions on an empty stomach.