What is malnutrition?

Malnutrition occurs when insufficient food has been eaten so that the body starts to use up its own reserves of energy and protein. Your reserves of sugar, fat and protein become depleted. This leads eventually to potentially severe consequences.

Is malnutrition a common problem?

You may think of malnutrition as something that occurs in so called developing or third world countries, particularly in Africa or India. It is true that malnutrition is quite common in those areas but it is also surprisingly common in the UK. Up to 40% of those admitted to hospital in the UK already show evidence of malnutrition. The reasons for finding malnutrition in the UK do not relate to shortages of food but to the effect of underlying illnesses, and/or poverty and social deprivation. Obesity is also due to poor nutrition but in this article, malnutrition refers only to those suffering from undernutrition, not excess nutrition. Malnutrition actually costs the UK more each year than obesity! It has been calculated that up to 3 million people are suffering from malnutrition in the UK. Could you be one of them?

How would you recognise malnutrition?

If you or perhaps a family member or carer are worried that you are developing malnutrition, the first thing to consider is whether you have lost weight without trying to diet. If you haven’t weighed yourself recently, have you noticed your belt, skirt, trousers or collar becoming loose? To be malnourished, you need to have lost at least 10% of your original weight. So if you weighed 10 stone when last well and you now weigh 9 stone, you are developing malnutrition. Even obese heavy people can become malnourished and at risk of problems without their weight going below the normal range. This is because the loss of muscle protein greatly exceeds the loss of fat from the body. Loose skin folds around the arms and legs may mask underlying malnutrition. The quicker weight is lost, the more problems may become apparent. These problems may be noted before you have realised that you have lost weight. Most people will note that they have not been able to eat so much before their weight begins to fall.

Measuring your risk of malnutrition

Healthcare professionals have developed a “Tool” to measure your risk of malnutrition. This is called the “MUST” tool. This stands for “Malnutrition Universal Screening Tool”, available on the British Association of Parenteral and Enteral Nutrition (BAPEN) website at; 

 If you have lost between 5 -10% of your original body weight unplanned, and have an acute illness likely to prevent you from eating properly for more than 5 days, you will score highly enough to be considered at risk of malnutrition without attention to your nutritional needs. If your BMI (Body Mass Index – calculated by dividing the square of your weight in kilograms by your height in centimetres) is already in the low range of less than 20, and especially if it is less than 18.5, your risks are even greater. This means that without attention to your needs, you have little room for manoeuvre if your illness does not resolve quickly and your ability to eat normally has returned. Malnutrition then becomes an additional risk factor which might delay your recovery or affect your ability to cope with the stress of your illness or surgery.

What problems occur with malnutrition?

As your reserves of fat and muscle decline, you may experience general weakness, fatigue, difficulty working or doing simple jobs about the house. You may notice the cold more as your insulating layers of fat disappear. Sleep patterns may be disturbed.

Cuts or wounds and fractured bones may not heal properly or as quickly. You may be at increased risk of infections such as pneumonia.

In children or adolescents, growth or puberty may be affected. Milestones may be delayed.

Women of menstruating age may experience menstrual disturbances or cessation of periods altogether. Infertility often occurs as a protective mechanism when women become malnourished. This can be reversed with good nutrition.

Older people often become dependent on others for basic care such as getting up out of a chair, going to the toilet or getting up stairs but these problems are far more common when old people have become undernourished. Falls and fractured hips and wrists are more common as muscles no longer support weight and bones become more brittle (osteoporosis). Bed sores may also develop due to immobility and undernutrition, particularly if confined to bed or a chair.

If you have undergone surgery or have been the subject of trauma, your recovery is likely to be prolonged unless measures are taken to remedy your lack of adequate nutrition before and after the event. Surgical wounds and “join ups” of the bowel inside you may not heal at all unless nutritional support has been given before the operation.

Symptoms of specific deficiencies may also become apparent (see table).

Your response to certain drugs/medications may be affected for example Warfarin which may become more powerful causing poor anticoagulant control and bleeding. You may also notice that alcohol has a more potent affect on you than before.

Liver dysfunction may occur and enlargement of the liver due to fat within it is sometimes found.

Swelling of the ankles (oedema) is common in malnutrition. Abdominal swelling is found in severe cases of malnutrition due to accumulation of fluid within the abdominal cavity (ascites).

Lack of adequate nutrition can also lead to deficiencies of specific nutrients such as vitamins or other essential substances. Sometimes, the first evidence of malnutrition is a specific deficiency disorder such as one of those shown in Table 1.

Table 1 Various deficiency states associated with malnutrition


Disease name

Appearances /symptoms

Vitamin A


Night blindness

Vitamin B1 (thiamine)


Wernicke-Korsakov syndrome

Shortness of breath due to heart failure; numbness and tingling of hands and feet. Impaired consciousness and brain function

Vitamin B2 (riboflavin)


Cracked lips/ sore tongue

Vitamin B3 (niacin)


Rash on sun exposed skin; diarrhoea

Vitamin B6 (pyridoxine)


Depression; Premenstrual tension

Vitamin B12(cyanocobalamin)

Pernicious anaemia/ sub-acute combined degeneration of the cord/Peripheral neuropathy

Numbness and tingling of hands and feet; fatigue and shortness of breath due to anaemia; visual disturbances.

Vitamin C


Bleeding gums, swollen painful joints; bleeding; mental disturbances; impaired wound healing

Vitamin D


Painful bones, fractures, impaired growth

Vitamin E


Anaemia in infants; heart and muscle disorders; numbness and tingling in hands and feet

Vitamin K


Bruising/easy bleeding

Folic acid


Tiredness, shortness of breath

Essential fatty acids


Skin rash


Hypocalcaemic tetany

Painful muscle spasms; impaired consciousness


Hypomagnesaemic tetany

Painful muscle spasms; impaired consciousness



Muscle weakness; palpitations; bowel dysfunction



Muscle cramps; dizziness; collapse; confusion



Thrush like rashes, peeling skin rashes, diarrhoea, impaired immunity



Anaemia, fatigue, sore tongue, blue sclera, difficulty swallowing (rare). Dry skin and poor hair quality.



Heart failure; muscle weakness





You already know you have an underlying condition such as Crohns disease…

In this case, your ability to eat enough to satisfy your body’s requirements is likely to be impaired. Often, such patients run along with their weight much lower than it should be or was before your illness. This situation can become accepted as the “norm” by the patient, relatives and even their doctors. This is why it is so important to think of malnutrition so that once recognised, it can be treated properly. The measures available to treat malnutrition are beyond this article but in brief, attention to the type of food you are able to eat or addition of oral supplements under the guidance of a properly qualified dietitian may be enough to restore your nutritional status to normal. If not, more aggressive measures may be required. These include feeding you via a small tube passed through your nose or tummy wall into the stomach or intestine. In a minority of difficult cases, intravenous nutrition is required. This is not always offered as often as it should be because local hospitals do not always have the experience or expertise to offer it or to do it properly. Asking your hospital doctor or GP for referral to the hospital nutrition team or to a specialist centre can be difficult but if you are clearly undernourished and not getting any better, this may be just what is needed to help you “turn the corner”. Surgeons who offer a non emergency abdominal operation when you have untreated malnutrition are best avoided.

There are many disease processes which are associated with deteriorating nutrition. For example: chronic chest diseases, heart failure, kidney and liver failure and numerous abdominal causes, strokes and other disorders of the nervous system.

In some distressing disorders, difficulties swallowing can be anticipated as the disease runs its course. In such cases, it is important that you discuss the future with your family and doctors. If necessary, it is strongly advised that you make an “Advanced Directive” to guide your family and doctors when the situation is no longer under your control.

What not to do if you are worried about malnutrition…


Don’t ignore it!


Don’t seek advice from so called nutritionists or complimentary medicine practitioners on the high street.

Don’t regard malnutrition and weight loss as an inevitable consequence of your underlying condition, even cancer.

Don’t ignore it or be embarrassed if you have any concerns bring up the subject with your GP or hospital doctors.

Don’t forget to make sure you are weighed when you visit hospital as a patient.

PINNT is here to support you and steer you in the right direction but primarily we are here to support you should and when artificial nutrition is commenced if it’s what you need.


PINNT would like to thank Dr Barry Jones for compiling this information.

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