Symptoms of malnutrition 

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


If you lose 5 -10% of your body weight in the course of three to six months and are not dieting, it could be a sign that you are at risk of being malnourished.

Sometimes weight loss is not obvious, as 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
  • taking a long time to recover from infections
  • delayed wound healing
  • irritability
  • poor concentration
  • finding it hard to keep warm
  • persistent diarrhoea
  • depression

A useful method of assessing whether you are malnourished is to measure your body mass index (BMI). This is a measurement that can determine if you are 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 are 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.

However, it is important to note that BMI and weight loss are not the only indicators of malnutrition. A person can be overweight or obese and still be malnourished. This can be the result of dietary consumption of foods and drinks which are high in fat and sugar but low in vitamins and minerals.

When to see your GP

See your GP if your BMI is lower than 18.5, you have 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 appearing 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 in their 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.

If you have any concerns about your child’s development or health, contact your GP.

Vitamin and mineral deficiency

Even if your BMI is in the healthy range, you may still not be getting enough vitamins and minerals.

Physical signs that you may have a vitamin or mineral deficiency include:

  • skin problems or rashes
  • swelling of your tongue
  • poor vision at night or in dim light
  • feeling out of breath and tired all the time
  • pain in your bones and joints

Page last reviewed: 04/02/2013

Next review due: 04/02/2015