You find yourself speaking harshly, losing patience or dramatizing the slightest remark… just before lunch. You are not “too sensitive”: this cocktail of hunger and tension even has a nickname, the hangry phenomenon (hungry + angry), studied very seriously by scientists.
A team from the University of Bonn and the University Hospital of Tübingen has just shown that this bad mood when we are hungry is not just due to a simple drop in sugar levels. Between your stomach, your brain and your emotions, a key player plays the conductors: the way you feel what is happening in your body. And then the story gets really interesting.
Glucose, Hormones, and Evolutionary Legacy: What Hunger Does to Your Body
When you go for hours without eating, blood glucose levels drop. This sugar is the main fuel for your cells, especially those of the brain. If it gets less, you may feel weak, confused, irritable, and have difficulty concentrating; in extreme cases of prolonged hypoglycemia in diabetic people, coma can occur, recall the authors relayed by Harmonie Santé. To restore the situation, the stomach produces ghrelin, the hormone that stimulates the appetite, and launches a whole chain of reactions.
Ghrelin stimulates the production of cortisol, the stress hormone, and adrenaline by the adrenal glands. These molecules increase available sugar by triggering gluconeogenesis in the liver, but they also modify the levels of dopamine and serotonin, two neurotransmitters involved in positive emotions and stress management. Result: you are more irritable, more angry over trifles. Researchers have even shown more aggressive behavior in hungry zebrafish. This combative reflex could be a legacy of our hunter-gatherer ancestors, for whom hunger gave an advantage in fighting for food.
Study Shows It’s All About How Hunger You Feel
The new study published in the journal eBioMedicine followed 90 healthy adults for four weeks. They all wore a sensor that continuously measured their blood sugar levels and answered, via an app, questions about their hunger, satiety and mood, several times a day. The researchers did find a link: when blood sugar dropped, mood declined. But this link disappeared as soon as they took into account the feeling of hunger declared by the participants. “In other words, it is not the glucose level itself that influences mood, but rather the intensity with which we consciously perceive this lack of energy.“, explains Dr. Kristin Kaduk, first author of the study.
This point refers to interoception, that is to say the awareness of one’s internal bodily signals (heartbeat, breathing, hunger, etc.). “Our results suggest that awareness of one’s own body (called interoception) may act as a mood regulator“, adds Professor Nils Kroemer, lead author of the research. He also specifies: “Good listening to body signals seems to help maintain emotional stability, even during energy fluctuations.“People who were more accurate at sensing their internal variations had fewer emotional roller coasters, even when their blood sugar was moving.
Learn to listen to your body to be less “hangry”
For Professor Nils Kroemer, this mechanism does not only concern small bursts of irritation at the end of the morning. He recalls: “Many diseases, such as depression or obesity, are associated with alterations in metabolic processes, says Professor Kroemer. Better understanding the link between body perception and mood can help improve long-term therapeutic approaches. For example, through targeted interoception training or non-invasive stimulation of the vagus nerve, which connects the organs to the brain and influences interoception.“This path opens the way to treatments where we work as much on the body’s signals as on thoughts.
On a daily basis, certain simple reflexes already limit the explosion of bad mood when we are hungry. Public health articles recommend not going too long hours without eating and focusing on healthy snacks rather than ultra-sweet foods that cause blood sugar levels to rise and then fall. Keeping a piece of fruit, a handful of oilseeds or a yogurt in your bag often helps avoid arguments at the end of the day, as does spotting the first signs of hunger before you’re at the end of your tether.