Sometimes we do not even need to see food. The smell of freshly baked bread, coffee or a meal cooking in the kitchen can suddenly make us think that we are hungry.

There is a reason for this. Smell is an important part of how we experience food and can influence appetite, food preferences and the expectation that we are about to eat. However, its effect on how much we actually consume is more complex.

The smell of food sends signals to the brain

When we smell food, the brain is not simply deciding whether the smell is pleasant. The scent can act as a sensory signal that tells us food is nearby or available.

Smell is closely connected with areas of the brain involved in perception, memory, reward and eating behaviour. This is one reason why a familiar food smell can remind us of a particular meal or experience and make us want that food more strongly.

Appetite can change before the first bite

Research suggests that exposure to food smells can increase subjective appetite, particularly for foods associated with the specific smell.

A recent systematic review of 43 studies found that most studies examining appetite and food craving reported an increase in sensory-specific appetite after exposure to food odours. However, findings on food choice and actual food intake were less consistent and appeared to depend on several factors.

In other words, smelling food can make us want it more, but that does not necessarily mean that we will eat more.

The body can start preparing for food

The sight, smell or even thought of food can trigger what is known as the “cephalic phase” of digestion. These are early preparatory responses that can occur before or as eating begins.

Research suggests that such food-related cues can influence several physiological responses, including saliva production and some gastrointestinal or metabolic processes. These responses are generally small and temporary, and their overall importance for eating behaviour is not completely understood.

Smells do not affect everyone in the same way

Our response can depend on the person, the type and intensity of the smell, whether we have already eaten and how familiar we are with the food.

For example, a particular smell may increase our desire for a specific food without necessarily increasing our overall hunger. Research also suggests that the effect on actual food consumption is not always consistent.

That explains a familiar everyday experience: we can smell something delicious and immediately think, “I want that”, even when we are not physically hungry.

What does this mean in everyday life?

Food smells are one of many signals that can influence eating behaviour. There is no need to think of them as either “good” or “bad”.

Instead, they can remind us to notice the difference between physical hunger and the desire triggered by a sensory cue. Both are real experiences, but they are not necessarily the same thing.

What to take away

The smell of food can activate appetite and make us think about or crave a particular food before we even taste it. Smell is an important sensory signal for the brain and is closely connected with eating behaviour.

The interesting part is that its effect is not absolute. What and how much we eat depends on much more than a single smell.