We like to think that our decisions are rational but in reality our behavior is determined by different factors, many of which are beyond our control and even our conscience. In fact, in recent years, very interesting studies have emerged that reveal how a simple variation in glucose levels can affect our decisions, determine our mood, and ruin our willpower.
What are the main effects of glucose on behavior?
1. Low blood glucose levels make us more aggressive
A study carried out at the universities of Amsterdam and Ohio has discovered that blood glucose levels are closely related to outbursts of anger, especially in a relationship. To reach these conclusions, they analyzed 107 married couples for 3 weeks, measuring their blood glucose levels twice each day.
Each participant was provided with 51 pins and a voodoo doll similar to their partner. At the end of each day, the person had to insert as many pins as their level of anger. Thus, it could be seen that the lower the glucose level, the more pins were stuck, which is a clear indicator of anger. Why? The key is in self-control.
2. Low blood glucose makes us lose control
Self-control, or willpower, as it is popularly known, is not an inexhaustible resource but depends on different factors, one of them being the level of glucose in the blood. Recent studies carried out at the University of Florida have shown that when we have to practice self-control we consume large amounts of glucose, so if we do not replace it, it will be more difficult for us to resist impulsivity, regulate our emotions and concentrate.
Actually, this is not a surprising result if we take into account that our brain uses glucose as its main fuel. Therefore, more complex mental processes, such as thinking and self-control, would consume large amounts of glucose. That is also the reason why we can avoid harmful foods at breakfast but as the day progresses, we give in to temptation.
3. The less glucose there is in the blood, the worse our decisions will be
Researchers from Harvard Business School have gone one step further and asked how glucose levels affect our decisions. After recruiting 56 people, they asked them not to eat or drink anything for three hours straight. When they arrived at the laboratory, half of them were offered a sugary soft drink and the other half a sugar-free drink.
Next, each participant had to make a series of decisions about certain jobs. Thus, the researchers were able to notice that those with low blood glucose levels made worse decisions, especially because they overlooked some fundamental details or because they focused exclusively on short-term benefits.
References:
Bushman, B. J. et. Al (2014) Low glucose relates to greater aggression in married couples. Proceedings of the National Academy of Sciences; DOI:10.1073/pnas.1400619111.
Bos, M. et. Al. (2012) Food for Thought? Trust Your Unconscious When Energy Is Low. Journal of Neuroscience, Psychology and Economic; 5(2): 124-130.
Gailliot, M. T. et. Al. (2007) Self-control relies on glucose as a limited energy source: willpower is more than a metaphor. Journal of Personality and Social Psychology; 92(2): 325-336.
