Our body is very clever and does a lot with the energy that comes from our food. Everybody has a basal metabolic rate (BMR) which is the amount of energy that our body needs just to stay alive (Henry, 2005).

This energy is used for breathing, keeping our hearts beating, maintaining our body temperature, building new cells, and ensuring our brains are working (Henry, 2005). Even if we were lying in bed all day and not moving at all, our bodies would still need energy to do all these basic things.

BMR and energy usage

Everybody uses a different amount of energy which means we all have different BMRs. This can depend on our age, gender, and the amount of muscle we have (Coxson, et al., 2004).

If we don’t eat enough food to give us this energy, our body tries to keep us alive. It does this by slowing down our BMR (by as much as 30%) to save as much energy as possible (Coxson, et al., 2004).

When we eat well, our BMR will speed up so our body can fully function.

Weight and shape concerns

The urge to binge happens more often when you have weight and shape concerns (Hansen & Johnson, 2016). These worries may lead you to create rules around avoiding certain foods but then your brain focuses on them more. By not allowing a food at all, it triggers an all or nothing response when you do eat it, as well as a sense of failure.

The brain needs lots of energy to function. It uses up to a fifth of the energy that comes from our food, even though it is only about 10% of our body weight. BMR is faster in teenagers than older people and adults (Herculano-Houzel, 2016).

Eating disorders and the body

Changes in brain chemistry may lead to us feeling sad, moody and irritable, and can lead to bad memory and fainting.

Our heart rate can slow, and we can develop low blood pressure and palpitations.

We may get problems in the blood such as anaemia and our bodies may be unable to build new proteins or muscle, so they break down organs instead. Therefore, our muscles, liver, gut, and kidneys shrink rapidly (Coxson, et al., 2004).

As you can see in the picture below, the organs in the eating disorder patient (bottom scan) have shrunk (Coxson, et al., 2004).

Eating disorders and the body (continued)

Our metabolism slows to protect our body and keep any energy it can.

Body fluids and electrolytes may become They are important in keeping all our organs working properly.

Our skin, nails and hair can go brittle and dry with an inadequate amount of food.

Our bones may also start to become brittle and weak because of the low calcium (Nierenberg, 2019). The image below shows a healthy bone (left) compared to a brittle bone (right).

We know it can sometimes be really difficult to tell people about difficulties around eating. Try and find an adult you trust and remember that they are there to help you and not judge.