In young people, chronic under-nourishment has an impact on health. Our brains weigh less than 10% of our bodyweight but use up to 25% of our oxygen and energy (Herculano-Houzel, 2016). To be happy, our brains need significant food and energy (especially carbohydrates!), but they only get what is left over from our body. Our brains use 7 times more energy than our muscles do.

Physical and mental health

Eating disorders can affect both physical and mental health. Mental health can be affected by becoming more anxious, feeling lower in mood, struggling to do the things that you used to enjoy. It can also mean that thoughts get more rigid and stuck and rules around food are more likely to develop. Physically, you might feel more tired, drained, and unable to participate as much in life.

The myelin sheath

The myelin sheath is a protective layer around the neurons (nerve cells in our brain) which helps to support lots of brain connections. Some brain cells have up to 10,000 connections in a healthy brain. The myelin sheath is a form of fat, and our brains need fats around our neurons to help electrical brain signals move quickly. This myelin is called “white matter” in our brains (Giagka, 2015).

If our bodies are not getting enough energy, our brains dissolve white matter and the myelin sheath. A healthy brain is composed of about 60% fat (Chang, Ke, & Chen, 2009), so when you are underweight, this gets digested to help keep you alive. This means that your body will need a lot of energy and fats to allow your brain to completely heal which can take up to 18 months (Seitz, Buehren, von Polier, & Konrad, 2014).

Brain changes

When someone is undernourished, changes start happening in the body to preserve the brain at all costs. Normally, the liver uses glucose from food to give us energy (which mainly comes from carbohydrates). If you are not eating enough, the body starts to use fat as its main fuel source. As your brain is made up of around 60% fat, it loses brain matter. This may lead to difficulties with attention, concentration, emotional responses, and attachments as well as higher levels of anxiety, depression, and obsessiveness. Young people may struggle to understand their illness, so may need support from others.

The patient with an eating disorder has lots of black spaces (where white matter has been lost). In the healthy person the brain is full with no gaps (Seitz, Buehren, von Polier, & Konrad, 2014). The brain only starts to recover very late on in treatment. It can take up to two years for being fully nourished for the brain to totally repair itself. Life with a starving brain can be a bit grey and dull, and you don’t get to experience the full joys of life. You can still do well at school and achieve academically but it takes so much more effort and work.

All of the symptoms mentioned will improve with weight restoration!