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Eating a healthy, balanced diet plays a vital part in maintaining a good level of all-round health and fitness and will avoid malnutrition.
Brought to you by NHS Choices

In order to stay healthy, we need to consume foods from a number of different food groups including:

  • carbohydrates,
  • proteins,
  • fats, and
  • dairy.

A healthy, balanced diet also includes eating a minimum of five daily portions of fruit and vegetables, many of which contain essential vitamins and minerals.

An inadequate diet can cause malnutrition

An inadequate diet can lead to malnutrition. Malnutrition is a condition which is caused by an imbalance between what a person eats and the nutrients that they need to maintain good health.

Malnutrition commonly occurs when someone does not eat enough food (sub-nutrition). However, it can also occur if a person has a poor diet that provides them with an incorrect balance of the basic food groups listed above.

Therefore, it is possible for an obese person, whose diet consists mainly of ‘fast food’, to be malnourished because this type of food lacks the nutrients that their body requires.

An inadequate diet can also lead to a person having a deficiency of one, or more, vitamins, minerals, or other essential substances.

For example, a vitamin C (ascorbic acid) deficiency can occur if a person does not include enough fresh fruit and vegetables in their diet. This can lead to a condition called scurvy.

See the ‘useful links’ section for more information about scurvy.

Who is affected by malnutrition?

In the UK, it is estimated that, at any one time, at least two million people are affected by malnutrition.

Anyone can become malnourished if, over a prolonged period of time, they do not consume enough food to fulfil their nutritional needs, or if they have an unhealthy diet. However, the groups who are most at risk from malnutrition are:

  • the elderly - particularly those who are in hospital, or institutionalised,
  • people with low incomes, or those who are socially isolated,
  • people with chronic (long-term) disorders - for example, eating disorders, such as anorexia nervosa and bulimia, and
  • people who are recovering from a serious illness, or condition - particularly those with  a condition that affects their ability to eat, such as a stroke.


Malnutrition can have a number of adverse effects on the body. If you are malnourished, your body will slow down and it will not work as well as usual.

The adverse effects of malnutrition

Typical adverse effects of malnutrition include:

  • reduced muscle and tissue mass,
  • decreased mobility and stamina as a result of muscle wasting,
  • breathing difficulties, and an increased risk of chest infection and respiratory failure,
  • wounds take longer to heal and illnesses take longer to recover from,
  • slower immune response which increases the risk of getting infections, and increases the length of time that it takes to recover from infection,
  • difficulty staying warm as a result of having less muscle and tissue mass, increasing the risk of hypothermia (the inability to maintain normal body temperature), and
  • poor libido (sex drive) and fertility problems.

If you are malnourished, there is also an increased chance that you will develop post-operative complications should you need to have surgery for another medical condition.

In some cases, malnutrition can also lead to feelings of apathy (indifference), tiredness, and depression.


Malnutrition is caused by a lack of essential nutrients, resulting in the inability of the body to function as efficiently as normal. A lack of nutrients in the body can be caused by a number of circumstances and conditions.

For example, in developing countries, such as in many African countries, chronic (long-term) malnutrition is a large scale and ongoing problem, which is the result of people not having enough food to eat on a daily basis.

In the UK, malnutrition is often be caused by:

  • an inadequate diet,
  • stomach conditions and digestive disorders, and
  • alcoholism.

An inadequate diet

Not eating enough food to maintain proper body function, or eating an imbalanced diet that does not provide you with the nutrients needed to maintain a good, all round level of health, will cause you to become malnourished.

An inadequate diet can occur for a number of reasons. For example, if you are unwell, or you are recovering from an illness, such as a stroke, throat or mouth cancer, or gastro-oesophageal reflux disease (GORD), you may develop dysphagia.

Dysphagia can arise as a complication of these conditions and, for some people, it makes it difficult to swallow certain foods, or liquids. Some people with dysphagia are completely unable to swallow.

See the ‘useful links’ section for more information about dysphagia.

Mental health conditions, such as depression, can sometimes make you feel like not eating and can lead to malnutrition. Similarly, eating disorders, such as anorexia nervosa and bulimia, can also result in malnutrition because the amount of food that is consumed by someone with an eating disorder is often very low.

See the ‘useful links’ section for more information about anorexia nervosa and bulimia.

Mobility problems, which are particularly common among the elderly, are another potential cause of malnutrition, as they can prevent people getting to the shops to buy food, or from preparing food for themselves.

Stomach conditions and digestive disorders

If the food that you eat is not digested properly, your body will be unable to absorb the nutrients that it needs to function effectively.

For example, if you have a stomach, or digestive, condition, such as ulcerative colitis (a condition that affects the large intestine, or colon), or Crohn’s disease (a condition that causes inflammation of the gastrointestinal tract), you may need to have a surgical procedure which is known as an ileostomy.

An ileostomy involves removing part of the small intestine. In some cases, the colon (large intestine) and rectum (back passage) may also need to be removed. If you have an ileostomy, you will need to have a low fibre diet for the first few months after the procedure, and you may need to take vitamin supplements until you are able to resume a normal diet.

See the ‘useful links’ section for more information about ileostomies.

Coeliac disease is a bowel condition that is caused by intolerance to a protein called gluten. In coeliac disease, the immune system mistakes gluten as being harmful and attacks it, damaging the lining of the intestines (gut) so that it is unable to absorb food properly.

If you have coeliac disease, you will need to exclude gluten from your diet, and you may also need to take vitamin and mineral supplements. See the ‘useful links’ section for more information about coeliac disease.

Diarrhoea and vomiting can also lead to the body losing vital nutrients and, in severe cases, can cause symptoms of malnutrition.


People who misuse alcohol can sometimes become malnourished because alcohol contains enough calories to stop you feeling hungry, but it does not contain the necessary nutrients that are required to stay healthy.

See the ‘useful links’ section for more information about alcohol misuse.


It is very important that malnutrition is detected as early as possible in order to prevent the condition getting worse, and to devise an appropriate nutritional treatment programme for the patient.

Malnutrition Universal Screening Tool

The Malnutrition Universal Screening Tool (MUST) has been designed by the Malnutrition Advisory Group (MAG) of the British Association for Parenteral and Enteral Nutrition (BAPEN) as an effective way of identifying adults (particularly the elderly) who are:

  • malnourished,
  • at risk from malnutrition, or
  • obese.

MUST is a five-step tool that can be used by health professional in hospitals, or in the community, to accurately identify those who are at risk from malnutrition. The tool also includes guidelines for introducing an effective treatment plan that is appropriate for the patient.

The MUST five-step plan involves:

  • Step 1 - measuring the patient’s height and weight to establish a body mass index (BMI) score using the chart provided in the plan. If it is not possible to obtain height and weight measurements, alternative procedures are given.
  • Step 2 - the percentage of unplanned weight loss is noted and scored using the tables provided in the plan.
  • Step 3 - any underlying illness, such as a psychological condition, is established and a score is given. It will be noted whether there has been, or is likely to be, no nutritional intake for five days, or more.
  • Step 4 - the scores from steps 1, 2 and 3 are added together to obtain an overall risk of malnutrition.
  • Step 5 - a care plan is developed using management guidelines and/or local policy.

MUST can only be used to identify malnutrition in adults, or adults who are at risk of becoming malnourished.  The tool is also not designed to identify deficiencies (or excesses) in the intake of vitamins and minerals.


Treatment for malnutrition will depend on its severity, and whether you have any underlying illnesses, or conditions, that are causing you to be malnourished. Any underlying causes will need to be addressed.

The National Institute for Health and Clinical Excellence (NICE) has produced guidelines for the treatment of patients with malnutrition.

They state that treatment should take into account the patient’s needs and preferences, and that the patient should have the opportunity to make informed decisions about their care and treatment in partnership with their healthcare professionals.

NICE also recommend that patients who are having nutritional support (and their carers) should be:

  • fully informed about their treatment,
  • given tailored information,
  • given the opportunity to discuss diagnosis, treatment options, and relevant physical, psychological, and social issues, and
  • given the contact details of relevant support groups, charities, and voluntary organisations.

Once malnutrition has been identified, or if there is a risk that you will become malnourished, the healthcare professional who is responsible for your care will devise an appropriate care plan for you. This healthcare professional may be a doctor or a dietician (a nutritional specialist).

The care plan

The care plan will set out the aims and objectives of your treatment, and will include treating any underlying conditions that are causing, or contributing to, your malnutrition.

Treatment will involve a programme of feeding using a specially devised diet, which may include additional nutritional supplements.

If you are severely malnourished, or unable to obtain enough nutrition orally to meet your nutritional requirements, artificial nutritional support may be needed

Your care plan will also involve carefully monitoring your progress, and periodically reviewing your treatment, in order to ensure that your nutritional needs are being met.


The healthcare professional responsible for your care will discuss eating and drinking with you, and will give you advice about making healthy food choices. They will be able to help ensure that you have a healthy, nutritious diet.

Your healthcare professional will work with you to ensure that you are consuming enough calories from the basic food groups - carbohydrates, proteins, fats, and dairy - and that you are getting a good supply of vitamins and minerals.

If you have problems with mobility, they may also be able to offer you assistance with food shopping and cooking.

In some cases of malnutrition, oral supplements may be needed if it is not possible to meet your nutritional requirements from food alone. An additional 250-600kcal (kilo calories) may be recommended.

If nutritional supplements are recommended, you will be given further dietary advice and counselling.

Artificial nutritional support

In cases of severe malnourishment, artificial nutritional support may be needed. The two main types of artificial support are known as:

  • enteral - where a tube is used to pass a liquid feed directly into your stomach, and
  • parenteral - where a sterile liquid is fed directly into your bloodstream.

Enteral feeding

If you are malnourished, and you are unable to eat or drink, you may need to have a special liquid diet which is fed directly into your stomach through a tube. This is known as enteral feeding.

A nasogastric tube will be inserted into your nose and passed down into your stomach, or small intestine. The other end of the tube will be attached to a small container that holds the liquid feed.

Parenteral feeding

It may not be possible for you to take nutrients directly into your stomach, or small intestine. If this is the case, a sterile liquid that is fed through a tube and into your blood, may be recommended. This is called parenteral feeding.

Monitoring your progress

As part of your treatment for malnutrition, the healthcare professional in charge of your care will monitor your progress on a regular basis in order to make sure that you are getting the correct amount of calories and the right nutrition to meet your nutritional requirements.

As your nutritional requirements change, adjustments may need to be made to your treatment. If your nutrition is being supported artificially, using a tube, this method of feeding will be stopped once you are able to eat and digest solid and liquid foods normally.


Malnutrition is often a significant problem both in healthcare settings, such as hospitals and care homes, and in the wider community.

The National Institute for Health and Clinical Excellence (NICE) has produced a set of guidelines to help UK health professionals identify those who are malnourished, or at risk of malnutrition.

The NICE guidelines have been designed to improve the way that the NHS deals with the problem of malnutrition. The guidelines recommend that:

  • On first admission to hospital, all inpatients should be weighed, measured, and have their Body Mass Index (BMI) calculated, and this should be repeated weekly. It should also be carried out on registration at GP surgeries.
  • At their first appointment, all hospital outpatients should be weighed, measured, and have their BMI calculated, and this should be repeated when there is clinical concern.
  • On first admission to a care home, all residents should be weighed, measured, and have their BMI calculated, and this should be repeated when there is clinical concern.
  • Screening should also be considered at other times - for example, during routine health check-ups, or at the same time as giving flu injections.
  • Nutritional support should be considered for those who are malnourished, or at risk of malnutrition, as defined by NICE guidelines.
  • All hospital trusts should have a multi-disciplinary nutrition support team consisting of a range of healthcare professionals, including doctors, such as gastroenterolgosists (specialists in the digestive system), gastrointestinal surgeons, and dieticians (nutritional specialists). At least one specialist nurse in nutrition support should also be employed.
  • All healthcare professionals who are directly involved in patient care should receive education and training on the importance of providing adequate nutrition, including oral, enteral and parenteral nutritional support, the potential risks and benefits, and when and where to seek expert advice.

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