According to professor Russell Keast, director of the Centre for Advanced Sensory Science at Deakin University, it’s called ‘sensory-specific satiety’ and it’s the reason we always have room for sweets - no matter how stuffed we feel post-dinner.
"Basically, this is what we experience when we eat one food to fullness. Our senses tell us we are no longer wanting to eat any more of that specific food. In other words, we are full," Keast told The Huffington Post Australia.
"Part of the response is actually sensory boredom - the food that excited us with promise of flavour delights is now boring. We are getting satiated but combine this with the fact that our flavour sensing system is overloaded with the food's flavour helps us stop eating.”
Then, when we present the tastebuds with the prospect of a new flavour experience, it makes us salivate once more.
“It may look and smell good and (from experience) we know sweet is appealing,” Keast explained. No more boredom with the food and the anticipation creates appetite - hence the dessert stomach."
"If the same food was presented, the desire to consume more of the same is not present,” he adds.
Researchers from the Lovisenberg Diakonale Hospital in Norway back this theory, adding that the sugar in sweet foods stimulates a reflex that actually expands the stomach. The result? We keep eating. And eating. And eating.
“If you eat dessert after you’re actually feeling stuffed you’re tricking your normal sensation of being full,” senior researcher Arnold Berstad explained in an issue of The Journal of the Norwegian Medical Association.
“A sweet dessert allows the stomach to make room for more food.”