How sniffing a lemon could make you feel THIN - but scientists say the scent of vanilla has the OPPOSITE effect

Sniffing a lemon could make you feel thinner but the scent of vanilla may have the opposite effect, scientists have found.

In the first study of its kind, researchers discovered that scents are able to change how people perceive their body image.

While having odours wafted under their nose, participants created an avatar of themselves that they felt represented their own size - with varying results.  

Experts now believe that odours could be worked into wearable devices - such as 'interactive clothes' - to boost people's self-esteem in daily life.

They also said the findings hold promise for new treatment for patients with body dysmorphic issues, preventing eating disorders in the process.

  

An estimated 30million in the US and up to 3.4million people in the UK suffer with an eating disorder, research suggests. 

The study took place at The Computer-Human Interaction (SCHI) Lab, University of Sussex, led by Giada Brianza, a first year PhD student at the lab.

She said: 'Our brain holds several mental models of one's own body appearance which are necessary for successful interactions with the environment.

'These body perceptions are continuously updated in response to sensory inputs received from outside and inside the body.

'Our study shows how the sense of smell can influence the image we have in our mind of our body and on the feelings and emotions towards it.'  Several previous studies have shown our senses - including smell - affect our experiences and emotions.

For example, smells can be categorised as pleasant, calming, or arousing.  

And research has shown that lemon and pepper are associated with spiky shapes, while raspberry and vanilla with rounded ones.

The researchers theorised that participants would feel thinner and lighter while smelling lemon and thicker and heavier when smelling vanilla based on initial work.

Twenty-two participants were instructed to walk on the spot while scents were released and then asked to adjust the size of an avatar on screen according to their perception of their body size. 

They were wearing headphones that delivered an enhanced sound of their own footsteps, recorded using special shoes.

Researchers found the scent of lemon resulted in participants' feeling lighter, while the vanilla scent made them feel heavier. 

These results were enhanced when combined sounds associated with that smell - established with previous work.

When a high-pitched sound was played with the lemon scent, participants felt even lighter.

When low-pitched sounds accompanied vanilla scents, they felt heavier even more-so. 

The team revealed how their findings could be used to develop therapies for people with eating disorders, of which people with negative image are at an elevated risk of.

Ms Brianza said: 'Being able to positively influence this perception through technology could lead to novel and more effective therapies… or the development of interactive clothes and wearable technology that could use scent to enhance people's self-confidence and recalibrate distorted feelings of body weight.'

Dr Ana Tajadura-Jiménez, a co-author from the Universidad Carlos III de Madrid, said: 'Our previous research has shown how sound can be used to alter body perception.

'We showed how changing the pitch of the footstep sounds people produce when walking can make them feel lighter and happier and also change the way their walk.

'However, nobody before has looked at whether smells could have a similar effect on body perception.'

The findings were unveiled at the 17th International Conference on Human-Computer Interaction on September 4 and are yet to be published.

WHY ARE SCENTS AND BODY IMAGE LINKED?

The link between our senses and our body image has been studied since the 1990s, making it a relatively new area of research.

Of all the senses, vision, touch and awareness of our own space are the most studied.

They have found body perceptions change depending on our environment. 

The researchers at University of Sussex knew the smell of lemon and vanilla evoked different emotional responses from people.

This was based on several prior studies - for example, research has shown that lemon and pepper were associated with spiky shapes, while raspberry and vanilla with rounded ones.

As well as this, smells can be categorised based on their emotional effects. Prior research has shown that some scents are classified more arousing and others more calming. 

In their own experiments, the team at University of Sussex investigated how scents are perceived generally.

Participants sat at a computer screen while smells were delivered directly into their nose through a nozzle.

They were then asked to describe the scents and how they collate with shapes and temperatures.

Lemon was associated with thin silhouettes, spiky shapes, high-pitched sounds, and coldness.

On the other end of the scale, vanilla was associated with thick silhouettes, rounded shapes, low-pitched sounds, and warmth.

This set the foundations for the second study, in which the researchers wanted to assess how the smells affected the participants' own body image perception.