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Malnutrition: What you need to know

Malnutrition refers to when a person’s diet does not have adequate nutrients or the proper nutritional balance for optimum health.

Malnutrition factors include poor dietary options, low wages, challenges in accessing food, and numerous physical and mental health conditions.

One type of malnutrition is undernutrition. It happens when the body isn’t getting enough food. This may result in delayed growth, weight loss or waste.

If a individual does not have the right nutritional balance, they may also be malnourished. Malnutrition can bring about obesity.

When an person has too little food, a poor diet, or a disease that prevents their body from having the right nutritional balance, it can have a serious effect on their health. This can become life-threatening in some situations.

This article looks in depth at malnutrition, including the causes, signs and related treatments.

What is malnutrition?

A person with malnutrition may experience tiredness, irritability, and an inability to concentrate.
A person with malnutrition may experience tiredness, irritability, and an inability to concentrate.

Malnutrition happens when a person gets too much of some nutrients, or too little.

Undernutrition happens when nutrients are missing because they consume so little food in general.

A individual suffering from undernutrition can lack the vitamins, minerals and other important substances that their body needs to work.

Malnutrition can lead to:

  • short- and long-term health problems
  • slow recovery from wounds and illnesses
  • a higher risk of infection
  • difficulty focusing at work or school

Some deficiencies can trigger specific health problems. For example:

A lack of vitamin A

Around the world, many children develop vision problems due to a lack of vitamin A.

A lack of vitamin C

A lack of vitamin C may cause scurvy. Scurvy is uncommon in the U.S. but it can grow if a person lacks a diverse diet with plenty of fresh fruits and vegetables.

Older adults, young children, those who drink a lot of alcohol and certain people with other disorders of mental health may be especially at risk.

An overall deficiency

Lacking all nutrients can lead to kwashiorkor, which is a “severe form of malnutrition.” One symptom of this condition is a distended abdomen.

A further possible consequence of extreme nutritional deficiency is marasmus. A person with a marasmus has very little muscle or fat on his or her body.


Some signs and symptoms of malnutrition include:

  • a lack of appetite or interest in food or drink
  • tiredness and irritability
  • an inability to concentrate
  • always feeling cold
  • depression
  • loss of fat, muscle mass, and body tissue
  • a higher risk of getting sick and taking longer to heal
  • longer healing time for wounds
  • a higher risk of complications after surgery

Eventually, a person may also experience difficulty breathing and heart failure.

In children, there may be:

  • a lack of growth and low body weight
  • tiredness and a lack of energy
  • irritability and anxiety
  • slow behavioral and intellectual development, possibly resulting in learning difficulties

Treatment is possible. In some cases, however, malnutrition can have long-term effects.

Anorexia nervosa is a mental health condition that can lead to severe malnutrition.


Malnutrition can happen for a variety of reasons. Such possible triggers are discussed further in the sections below.

A low intake of food

Many people experience obesity due to lack of food or because they have trouble consuming or absorbing nutrients.

This can happen as a result of:

  • cancer
  • liver disease
  • conditions that cause nausea or make it difficult to eat or swallow
  • taking medications that make eating difficult — due to nausea, for example

Mouth problems like poorly fitting dentures can also lead to malnutrition.

Mental health conditions

Undernutrition or malnutrition can affect people with:

  • depression
  • dementia
  • schizophrenia
  • anorexia nervosa

Social and mobility problems

Factors which can affect the eating habits of an person and potentially lead to malnutrition include:

  • being unable to leave the house or reach a store to buy food
  • finding it physically difficult to prepare meals
  • living alone, which can affect a person’s motivation to cook and eat
  • having limited cooking skills
  • not having enough money to spend on food

Digestive disorders and stomach conditions

Even a balanced diet can’t avoid malnutrition if the body doesn’t consume nutrients effectively.

Examples of digestive and stomach conditions that may cause this include:

Alcohol use disorder

Consuming much alcohol can cause gastritis or long-term pancreatic damage. These problems will make it difficult to digest food, consume vitamins and generate metabolism-regulating hormones.

Alcohol also contains calories so after drinking it a person may not feel hungry. So they can not consume enough nutritious food to supply vital nutrients to the body.

Risk factors

In certain parts of the world, a lack of food can contribute to widespread and long-term malnutrition.

Nevertheless, in the wealthiest nations those at highest risk of malnutrition are:

  • older adults, especially when they are in the hospital or long-term institutional care
  • people who are socially isolated — for example, due to mobility issues, health problems, or other factors
  • people with a low income
  • people recovering from or living with a serious illness or condition
  • those who have difficulty absorbing nutrients
  • people with chronic eating disorders such as bulimia or anorexia nervosa

Many people may need to take supplements if they are following a specific diet.


When an person shows or experiences any symptoms of malnutrition, the first move is to find out why.

When a doctor suspects Crohn’s disease, celiac disease or other disorder, laboratory tests can be done to validate a diagnosis. Treating those conditions will improve the nutritional status of an person.

They may also carry out the following:

  • blood tests for general screening and monitoring
  • tests for specific nutrients, such as iron or vitamins
  • prealbumin tests, as malnutrition commonly affects levels of this protein
  • albumin tests, which may indicate liver or kidney disease

A tool to identify risk

Many methods can help recognize people who have or are at risk of malnutrition.

One way to test adults is by using the Malnutrition Universal Screening Tool (MUST). Evidence has shown this is a effective method.

Experts developed this tool to identify adults with malnutrition, or a high risk of malnutrition, particularly older adults. It’s a five-step program that will help health care providers identify these disorders and manage them.

The five steps are as follows:

Step 1: Measure a person’s height and weight, calculate their body mass index (BMI), and provide a score.

Step 2: Note the percentage of unplanned weight loss and provide a score. For example, an unplanned loss of 5–10% would give a score of 1, while a 10% loss would score 2.

Step 3: Identify any mental or physical health conditions and provide a score. For example, if a person has been acutely ill and taken no food for over 5 days, the score will be 3.

Step 4: Add the scores from steps 1, 2, and 3 to obtain an overall risk score.

Step 5: Use local guidelines to develop a care plan based on the score.

The score will be one of the following:

  • low risk: 0
  • medium risk: 1
  • high risk: 2 or more

Doctors use MUST only to recognize general malnutrition or the risk of adult malnutrition. The test won’t detect clear nutritional imbalances or shortcomings.

Nutritional-deficiency anemia will result if a person’s diet can not provide the nutrients they need.


If a doctor diagnoses malnutrition, a treatment plan will be made for that person. The patient may also need to visit a nutritionist and other health care providers.

Treatment may depend on the severity of the malnutrition and any other problems or complications underlying it.

It may include:

  • ongoing screening and monitoring
  • making a dietary plan, which might include taking supplements
  • treating specific symptoms, such as nausea
  • treating any infections that may be present
  • checking for any mouth or swallowing problems
  • suggesting alternative eating utensils

In severe cases, a person may need to:

  • spend time in the hospital
  • gradually start taking in nutrients over a number of days
  • receive nutrients such as potassium and calcium intravenously

The health-care team of the individual will continue to track them and make sure they get the nutrients they need.


To avoid malnutrition, people must eat a variety of nutrients from a variety of types of food.

Older adults, young children, people with serious or chronic disease and others may require extra treatment to ensure the nutrients they need are received.

Everyone who starts showing symptoms of malnutrition or undernutrition should see a diagnosis and care physician.

Good care is typically available in the U.S., but the recovery outcome and duration may depend on the cause of malnutrition.


I take care of an 80-year-old lady, and it is difficult to get her to eat, except for ice cream, cakes, chips, and other unhealthful things. I don’t want to give her these things, but otherwise she won’t eat. How can I help her?


Consider milkshakes with added protein or milkshakes that are meal replacement options with added nutrition. Be sure to offer a variety of fruits and vegetables as snacks, and try to eat these snacks with her to make the experience more social.

Add chopped nuts, wheat germ, or extra eggs to cakes, and add less sugar so that there is more protein in what she is eating. For salty snacks, try dehydrated or baked salty vegetable rather than potatoes. Try adding melted cheese to appropriate dishes.

Also, consider a multivitamin. Debra Rose Wilson, Ph.D., MSN, R.N., IBCLC, AHN-BC, CHT

Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical

Chukwuebuka Martins

Chukwuebuka Martins is a writer, researcher, and health enthusiast who specializes in human physiology. He takes great pleasure in penning informative articles on many aspects of physical wellness, which he then thoroughly enjoys sharing to the general public.