Malnutrition - Symptoms of malnutrition

The most common symptom of malnutrition is unplanned and unexplained weight loss.


If you lose 5-10% or more of your body weight within three to six months and you're not trying to lose weight, it could be a sign that you're at risk of malnourishment.

Sometimes, weight loss isn't obvious because it occurs slowly, over time. You may notice that your clothes, belts and jewellery gradually feel looser.

Other signs of malnutrition may include:

  • feeling tired all the time and lacking energy
  • frequently getting infections 
  • taking a long time to recover from infections
  • delayed wound healing 
  • poor concentration
  • difficulty keeping warm
  • depression

A good way of assessing whether you're malnourished is to work out your body mass index (BMI). BMI is a measurement that shows whether you're a healthy weight for your height.

For most adults a healthy BMI is between 18.5 and 24.9. Having a BMI under 18.5 could suggest you're at a high risk of being malnourished, although you may also be considered at risk if you have a BMI between 18.5 and 20.

You can check your BMI using the BMI healthy weight calculator.

It's important to note that BMI and weight loss aren't the only indicators of malnutrition. A person can be overweight or obese and still be malnourished. This can be due to having a diet consisting of food and drink that's high in fat and sugar but low in essential vitamins and minerals.

When to see your GP

See your GP if your BMI is lower than 18.5, you've lost more than 5-10% of your body weight over the last three to six months, or you experience the symptoms listed above.


Symptoms of malnutrition in children can include:

  • failure to grow at the expected rate, both in terms of weight and height (known as "failure to thrive")
  • changes in behaviour, such as being unusually irritable, sluggish or anxious
  • changes in hair and skin colour

When to see your GP

Your child’s weight and physical development should be regularly assessed by your GP or a health visitor during your child's first few years of life.

As part of the National Child Measurement Programme, children in Reception and Year 6 are weighed and measured during the school year.

Contact your GP if you have any concerns about your child’s health or development.

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