Image: Nynke van der Laan
Vending machines at every street corner, birthday cakes at work, and creamy Frappuccino’s on-the-go. We are constantly tempted by tasty energy-rich foods everywhere we go. Yet, many of us still manage to avoid gaining weight. Why is it that our waistlines respond in different ways to this ‘obesogenic’ environment? Since all eating decisions are made between our ears, it seems likely that not everyone’s brain responds the same way to food. We recently reviewed how personality relates to the way your brain responds to food? At a party, is it usually you who makes a splash, or is it the other people around you? The extrovert-introvert spectrum is probably the easiest personality characteristic to spot in a person. Whereas extraverts are outgoing and talkative, introverts are more reserved and prefer solitary activities. Unfortunately, there is a downside to this apparent talkative and energetic extrovert personality type: they are more likely to be overweight. Scientists have long known that the brains of extraverts and introverts differ. For example, extraverts have a preference for immediate rewards and they behave more impulsively. Surprisingly, our review did not find evidence supporting the idea that the brains of extroverts (versus introverts) respond differently to foods.
Another general personality characteristic which has been related to overweight and overeating is neuroticism. Besides the strong response to stress, people high in neuroticism have stronger negative emotions like fear, anxiety, and guilt. Our review showed that neuroticists have a stronger response in the striatum, a core reward brain area, when they see their favourite chocolate brand. Chocolate makes us all happy, but could it be that the dark-minded neuroticists benefit from this comforting ‘brown gold’ even more?
A general personality characteristic that might protect against overweight is self-directedness or conscientiousness, which refers to being highly organised and succeeding to act in line with personal goals. These individuals are highly punctual (always arriving first at an appointment) and they never miss a deadline. It turned out that they have a weaker emotional response to foods, as illustrated by weaker amygdala activation.
Besides these general personality characteristics there are several food-specific characteristics. For example, some people are highly prone to indulge when they smell or see a tasty food (‘external eaters’) or when they experience mild feelings of hunger (‘hunger susceptibility’). Many of these food-specific personality characteristics are interrelated and can be explained by more general personality characteristics, such as those mentioned above. Individuals high on these characteristics have stronger reward responses to palatable snacks and this makes it more difficult to resist them.
A second line of food-specific personality characteristics is related to dietary control. Although they claim to watch their weight, people high in self-reported dietary control often fail at limiting their intake. Interestingly, they mainly overeat after a dietary violation, also referred to as the ‘disinhibition effect’. In line with this, they have stronger reward-related brain responses to food after such a dietary violation. With almost 50% of the female population being high in self-reported dietary restraint we all have a female relative who claims to be on a diet but does not hesitate to take a second piece of cake at your birthday party.
Within the Nudge-It project, this review will form the basis for the FORC toolbox with which we will measure food-relevant personality characteristics.
link to the FoRC toolbox