Malnutrition (undernutrition) is caused by a lack of nutrients in your diet, either due to a poor diet or problems absorbing nutrients from food.
Certain things can increase a person's risk of becoming malnourished.
Some conditions that can lead to malnutrition include:
You can also become malnourished if your body needs an increased amount of energy – for example, if it's healing after surgery or a serious injury such as a burn, or if you have involuntary movements such as a tremor.
Some types of medication may increase your risk of developing malnutrition.
Some medicines have unpleasant side effects – such as loss of appetite, diarrhoea or nausea – that could mean you eat less or don't absorb as many nutrients from your food.
The following factors can also contribute to malnutrition:
In the UK, malnutrition in children is commonly caused by long-term health conditions that:
Some children may become malnourished because of an eating disorder or a behavioural or psychological condition that means they avoid or refuse food.
Malnutrition as a result of a poor diet is rare in the UK, but may occur if a child is neglected, living in poverty or being abused. Call the NSPCC helpline on 0808 800 5000 if you're concerned about a child.