This post is also available in Dutch.
The holidays season is right around the corner, which means we will be grouped around the dinner table soon enough. All kinds of delicious dishes appear on the table, and when you think you are not able to eat another bite, your aunt unveils an amazing looking dessert. Luckily, you always have room for dessert!
But how can that be, even when you have just finished an entire Christmas meal? Research shows that there is a psychological as well as a physiological explanation.
Sensory specific satiety: the psychological dessert stomach?
A large part of this paradoxical effect can be explained by a phenomenon called ‘sensory specific satiety’. This means that when you have eaten a lot of food with a particular flavour, you don’t feel like eating more of it, whereas you do want to eat something with a different flavour. This is driven by habituation: a stimulus decreases in intensity when repeatedly exposed to it. Habituation occurs in all types of sensory stimuli, such as the feeling of clothes on your body. Something similar happens when you eat a lot of food with a similar flavour; the reward you experience keeps decreasing. But when you eat something with a very different flavour, you experience a new stimulus: This food acts as a reward again and tastes extra good. From an evolutionary perspective this is very useful: you will bring variation in your diet and eat different types of nutrients. A small disadvantage is that you’re inclined to eat more when a meal is varied than when it is not: even up to 60% more!
Sensory specific satiety also occurs in the brain: An experiment where participants’ brains were scanned while they ate chocolate showed that the orbitofrontal cortex plays an important role, which is a brain region involved in processing flavour. The more chocolate the participants ate, the less activity was seen in the part of the orbitofrontal cortex that is linked to rewards. What’s more, there was more activity in the part of the orbitofrontal cortex that is linked to aversion. So not only does the reward of the flavour decrease, you may even start to dislike the food.
More room in your stomach
The fullness of your stomach of course also determines your feeling of saturation. When your tongue tastes that a new rewarding food is coming, your body will prepare for its arrival: the lining of your stomach will relax, and there will be more room. This effect is larger when food contains more sugar. So there literally is more room for dessert!
All of this comes in handy during the holiday season: even after a fulfilling dinner you can enjoy the delicious ice cream sundae your aunt has made. But you can also use this principle in a healthy way when it’s time for new year’s resolutions: if you vary in eating different healthy snacks, you will eat more healthy products. Sort of fooling yourself…