Eating is often believed to be entirely under our conscious control – we choose to eat when we are hungry or when we feel tired and need more energy. Because of this, people often believe that overeating is caused by a lack of self-control and under-eating is a deliberate attempt to change our body, usually in response to perceived ideals about body shape. While unrealistic images in the media can have an effect on young people’s self-esteem and body image, other factors may also affect our eating. Research has begun to explore how our awareness and perception of our body signals (known as interoception) contribute to disordered eating.
Interoception includes perceiving various internal sensations from the body. It means noticing things like how quickly your heart is beating, how heavily you are breathing, how hot or cold you are, and whether you are feeling hungry or full. It can occur without us even knowing it, for example, when our body regulates our blood sugar levels. Or it can be very noticeable, such as our heart thumping when we give a presentation.
Good interoception is vital for “intuitive eating” - eating in response to body signals when we are hungry rather than for other reasons, such as knowing it is lunchtime or feeling emotional. Eating for different reasons is normal, but intuitive eating is important for maintaining a healthy body weight, and when it is disrupted, it can lead to eating problems.
Eating disorders, such as anorexia, bulimia and binge eating disorder, involve abnormal eating patterns and attitudes towards eating that significantly interfere with day-to-day life. These disorders are estimated to affect more than 10.5m people globally. The most commonly affected groups are teenage girls and adult women, but more and more males and younger girls are being diagnosed with eating disorders.
Different eating disorders have different characteristics. People with anorexia have very low weight and an intense fear of gaining weight. They may restrict their food intake or binge eat and purge. People with bulimia experience episodes of binge eating followed by purging. And binge eating disorder is characterised by binge eating without purging.
Research has found that people with anorexia and bulimia find it difficult to perceive internal signals from their body. For example, they struggle to count their own heartbeats and struggle to perceive pain. They also report difficulties recognising signals from inside their body. Brain scans show that the brain areas used for interoception are different in people with eating disorders compared with those without eating disorders.
It makes sense that these difficulties would be linked to eating disorders. If you struggle to notice when you are hungry, you may under-eat. And if you struggle to notice when you are full, you may binge eat.
The link to emotions
Interoception also affects our emotional experiences. Noticing changes in our body is important for realising we are experiencing an emotion. A beating heart and quick breathing can mean we are excited or nervous, and feeling sick can mean that we are disgusted. The stronger our perception of these internal body signals, the more intense our emotions seem. People who have difficulties identifying and describing their emotions also struggle to perceive other signals from their body.
Emotional problems are common in eating disorders, so perhaps interoceptive problems make it difficult for us to notice fullness and hunger and contribute to emotional difficulties and disordered eating as a coping mechanism.
Although it looks as though a poor reading of body signals is linked with eating disorders, we do not yet know whether it causes eating disorders or vice versa. Perhaps having an eating disorder encourages people to ignore body signals, making it easier to fast or binge, leading to poor interoception. Or perhaps having this in the first place makes it difficult for you to learn about when you are hungry or full, leading to abnormal eating habits.
Read more: Why some people overeat when they're upset
Researchers do not fully understand how interoception and eating habits develop, especially during childhood and adolescence, but we know that adolescence is a time when eating difficulties often begin and interoceptive abilities get worse. So, to understand the relationship between this and eating disorders, we need to conduct more long-term studies to examine this ability as a person grows up. These studies are currently underway. And we’re currently looking for participants for a study into how awareness of our bodies affects the way we eat.
Studying interoception across adolescence is also important for understanding other disorders, as differences in being able to read body signals are seen in many psychological conditions, including anxiety and depression. As mental health issues during adolescence can have severe long-term consequences, identifying the factors involved during childhood is essential for early intervention and successful treatment.
Studying interoception in childhood may be one way of determining how these disorders come about and could help us to understand the relationship between our inner experiences and how we interact with the world.