Why there’s always room for dessert – an anatomist explains

You push back from the table after Christmas lunch, full from an excellent feast. You really couldn’t manage another bite – except, perhaps, a little bit of pudding. Somehow, no matter how much you’ve eaten, there always seems to be room for dessert. Why? What is it about something sweet that tempts us into “oh, go on then”?

The Japanese capture this perfectly with the word betsubara, meaning “separate stomach”. Anatomically speaking, there is no extra compartment, yet the sensation of still having space for pudding is widespread enough to deserve a scientific explanation.

Far from being imaginary, the feeling reflects a series of physiological and psychological processes that together make dessert uniquely appealing, even when the main course has felt like the limit.

A good place to start is with the stomach itself. Many people picture it as a fixed-size bag that fills steadily until it can take no more, as though another mouthful would cause it to overflow.

In reality, the stomach is designed to stretch and adapt. As we begin to eat, it undergoes “gastric accommodation”: the smooth muscle relaxes, creating extra capacity without a major increase in pressure.

Crucially, soft and sweet foods require very little mechanical digestion. A heavy main course may make the stomach feel distended, but a light dessert, such as ice cream or mousse, barely challenges its workload, so the stomach can relax further to make space.

Hedonic hunger

Much of the drive to eat pudding comes from the brain, specifically the neural pathways involved in reward and pleasure. Appetite is not governed solely by physical hunger. There is also “hedonic hunger”, the desire to eat because something is enjoyable or comforting.

Sweet foods are particularly potent in this respect. They activate the brain’s mesolimbic dopamine system, heightening motivation to eat and temporarily weakening fullness signals.

After a satisfying main course, physiological hunger may be gone, but the anticipation of a sugary treat creates a separate, reward-driven desire to continue eating.

Another mechanism is sensory-specific satiety. As we eat, our brain’s response to the flavours and textures on the plate gradually diminishes, making the food less interesting. Introducing a different flavour profile – something sweet, tart or creamy – refreshes the reward response.

Many people who genuinely feel they cannot finish their main course suddenly discover that they “could manage a little pudding” because the novelty of dessert re-engages their motivation to eat.

Desserts also behave differently once they reach the gut. Compared with foods rich in protein or fat, sugary and carbohydrate-based foods empty from the stomach quickly and require relatively little early breakdown, contributing to the perception that they are easier to accommodate even when you are full.

Timing plays a role, too. The gut-brain signalling that creates the sensation of fullness does not respond instantly.

Hormones such as cholecystokinin, GLP-1 and peptide YY rise gradually and typically take between 20 and 40 minutes to produce a sustained sense of satiety. Many people make decisions about dessert before this hormonal shift has fully taken effect, giving the reward system space to influence behaviour.

Restaurants, consciously or otherwise, often time dessert offerings within this window.

Layered onto these biological processes is the influence of social conditioning. For many people, dessert is associated with celebration, generosity or comfort. From childhood onwards, we learn to regard puddings as treats or as natural components of festive meals.

Cultural and emotional cues can trigger anticipatory pleasure before the food even arrives. Studies consistently show that people eat more in social settings, when food is freely offered, or during special occasions – all situations where dessert typically features.

So the next time someone insists they are too full for another mouthful of dinner but somehow finds space for a slice of cake, rest assured: they are not being inconsistent. They are simply experiencing a perfectly normal and rather elegant feature of the human body.

Michelle Spear does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.