Shopping for food when you’re hungry is never a good idea. It’s no surprise that candy bars and chocolate fudge cake are hard to resist when your stomach is rumbling.
But fascinating new research into hunger and cognitive function reveals a surprise: When you’re hungry, you’re not limited to making unhealthy choices regarding food alone. You’ll also make bad decisions in areas that have nothing to do with food.
There have been a number of studies over the years investigating the impact food has on decision making.
One of the most famous clinical studies is the Stanford marshmallow experiment of 1972. During this study, researchers offered children either an immediate food reward or, if they waited 15 minutes, an even bigger reward.
Delayed Gratification “Wins”
Researchers found that the children willing to delay gratification went on to have better life outcomes than the ones who ate their marshmallow right away. In fact, those unwilling to wait were labeled “impulsive” by the researchers.
This study has sparked much debate over the developmental ability of young children to practice patience when faced with something they desire. Some researchers suggested that a study on adults would have different outcomes. So, it’s no surprise that a team of psychologists performed a modern version of the experiment to dig deeper into the issues.
The psychologists from the University of Dundee in Scotland enrolled 50 young adults who could choose rewards of food or non-food, such as money and music downloads—all offered in a randomized order.
The adults fasted for ten hours before taking the immediate reward test. Then, they ate a meal and two hours later, took the tests again.
When it came to food rewards the participants chose smaller, immediate rewards. When it came to larger, non-food rewards that would arrive at a later date, researchers were surprised that participants also expressed a greater preference for smaller, immediate rewards.
In other words, if you’re not hungry, you’ll wait for a larger reward. If you are hungry, you probably won’t. In fact, when participants were hungry, they were only willing to wait three days for their non-food reward. On the other hand, once satiated, participants were willing to wait 35 days to receive double the non-food reward.
Hunger Inspires Impulsivity
The Dundee researchers believe this indicates that hunger causes people to act in a more impulsive, impatient way even when the decisions they make won’t alleviate their hunger.
“We found there was a large effect,” commented joint author Benjamin Vincent. “People’s preferences shifted dramatically from the long to short term when hungry.”
He went on to explain how this knowledge can empower people because they can see how it might bias their decision-making.
“Say you were going to speak with a pension or mortgage advisor – doing so while hungry might make you care a bit more about immediate gratification at the expense of a potentially rosier future.”
Dr. Vincent couldn’t offer an explanation of what’s happening in the brain to cause us to behave in this way, so scientists from Harvard tried to find the answer.
Food Hormone Plays Key Role in Decision Making
Recent animal research suggests the hormone ghrelin, which signals the brain for the need to eat, also plays a part in impulsive choices and behaviors.
To see if this applied to humans, the research team enrolled 84 females between the ages of ten and 22. Of the 84, 50 had eating disorders which conditioned them to grow resistant to the effects of ghrelin.
All participants had a period of fasting, then had blood tests to measure ghrelin levels both before and after a standardized meal. After the meal they took an immediate rewards test called “delay discounting task”, in which they were asked to make choices involving money. For example, each woman could choose to accept $20 today or wait 14 days for four times that amount, $80.
The result was that the healthy girls and young women with higher levels of the hormone after fasting were biased towards the immediate, smaller reward, indicating more impulsive choices. However, those with eating disorders were not biased towards the smaller rewards because they were unaffected by the hormone.
This novel finding suggests the hormone ghrelin plays a part in behavior that goes beyond food.
Food Really is Fuel for a Healthy Brain and Healthy Behavior
Co-investigator, Professor Franziska Plessow, explains, saying, “Our results indicate that ghrelin might play a broader role than previously acknowledged in human reward-related behavior and decision making, such as monetary choices. This will hopefully inspire future research into its role in food-independent human perception and behavior.”
This is a fascinating area of research. In my mind it’s scientific reinforcement of the long-held belief that breakfast is the most important meal of the day. Whether you’re going to work, school or enjoying your favorite hobby, eating a healthy, nutritious breakfast will help your brain and your body function at its best. And if you’re about to make an important financial or life decision, don’t skip lunch. Consider eating before making your choice.
In my personal experience, I know I become a bit deranged about food when I’m hungry. I don’t make good decisions – it’s not only a bad time to go grocery shopping, it’s also a bad time to decide what the next meal will be. I’m much more likely to eat something unhealthy that’s quick to fix, or even go to a restaurant and overeat. It’s not hard to believe the same derangement carries over to non-food decisions.