The science of ‘hangry’: why we sometimes snap or make rash decisions on an empty stomach
Some of us are prone to acting impulsively under the influence of hunger. Scientists explain the mechanisms that cause this and what we can do to stop feeling that way
Have you ever tried to make a decision on an empty stomach and later wondered why you bought five packets of potato chips at the convenience store or made a rash choice in a budget meeting that you struggled to justify to the boss?
The hunger hormone ghrelin, which is released before meals and increases appetite, has a negative effect on decision making and impulse control, according to a recent study conducted by the University of Gothenburg. Previous studies have also suggested that people are more likely to make risky financial choices when they’re hungry, and one Israeli study even found that judges make more parole decisions in favour of prisoners after food breaks.
So how does hunger impair decision making? Mood, especially negative emotions such as anger, may connect the dots between feeling hungry and choosing poorly.
When the body is low on glucose the brain warns of a life-threatening situation and it becomes harder to concentrate, regulate temperament and behave within socially accepted norms. Low glucose levels also cause the brain to release stress hormones such as adrenaline and cortisol. If you’ve ever snapped angrily at someone when you felt hungry, you’ve probably experienced being “hangry”, the word used to describe feeling angry due to hunger.
According to Dr Benjamin Scheibehenne, a professor of cognition and consumer behaviour at the University of Geneva, in Switzerland, feeling angry when hungry can have a particularly detrimental effect on decisions about food.
“There is some research showing that people who are hungry are a little bit more impulsive, particularly when it comes to the consumption of unhealthy food,” he says. “People make very different decisions depending on what emotional state they’re in and they find it difficult to anticipate that their emotions may change.
“If you’re very hungry it’s very difficult to imagine what your appetite and your preferences would be like in a state where you’re not hungry. For that reason, people may choose to purchase very different things when they’re hungry as compared to when they’re not hungry.”
Sarah Dash, a researcher from the Food and Mood Centre at Deakin University, in Australia, says a good mood may give us perspective and the ability to make choices that will benefit the body long-term, while a bad mood invokes single-minded behaviour that aims to rid the body of negative emotions.
“When we are in a good mood, we may have the mental and emotional resources to think more broadly about things like long-term health or diet choices,” she says. “When we’re feeling low, we may crave foods that are comforting to us.”
Some experts believe the effect of hunger on choice is less about an emotional feeling of hunger and more about feeding the brain with insufficient or inadequate fuel. “Basically, when you’re hungry you have a slower reaction time, but it doesn’t make you a poor decision maker,” says Dr Jetty Lee from the School of Biological Sciences at The University of Hong Kong.
“It’s not about inaccurate information, it’s that you’re slower. When you’re hungry your insulin level goes up and you start breaking down all the necessary glucose in the body and if you don’t have enough glucose you’re not getting enough energy in your brain to function.”
Dietitian Dr Wendy Ma, a senior programme director in the Division of Health and Applied Sciences at HKU Space, says insufficient amounts of serotonin, which is synthesised from the amino acid tryptophan and found in nuts, cheese and red meat, and the omega-3 fatty acids in oily fish, flaxseed, walnuts and canola oil can impact mood and, by extension, decision making.
“When your serotonin levels are normal you tend to feel more happy, calm, focused, less anxious and more emotionally stable,” she says. “Low levels of omega-3 fatty acids are associated with depression and being more impulsive, while adequate intake can improve mood, and extrapolating from that may affect decision making.”
Carbohydrates make tryptophan more available to the brain, so Ma says it’s important to eat sufficient amounts of whole grain carbohydrates – about three to eight bowls a day, according to the Department of Health – to maintain a stable mood.
“If you have carbohydrates in the diet you’re more likely to impact on serotonin levels than eating more protein,” she says. “There’s no evidence that extra carbohydrates are going to improve your mood, but if you don’t have enough it’s going to affect your mood.”
Both Ma and Lee say skipping meals, and eating philosophies such as intermittent fasting, can lead to impaired cognitive function, so the best way to stabilise your mood is to eat regular meals.
Lee recommends including a variety of high-protein and whole grain carbohydrate foods in your breakfast. “It’s the first energy intake that can increase the glucose that’s available to the brain, so eating breakfast means your brain function is much better,” she says.
For office workers stuck behind a desk through lunch or past dinner time, Ma suggests keeping a stash of healthy snacks, such as nuts, fruit and yoghurt on hand to prevent energy dips and potential poor decisions.
And if you’re caught short and need to make a decision despite feeling hungry and angry, Scheibehenne recommends using the brain fuel you have left to channel some perspective. “Keep in mind that the kind of decisions you’ll be making when you’re hungry may be different from the decisions you’ll be making when you’re not hungry any more.”