Malnutrition that occurs when the body does not receive enough food. 

Malnutrition results in progressive weight loss. It is common in older people, especially those with Alzheimer’s disease. Depending on whether the person is at home (10%), in an institution (30%), or in the hospital (70%), its prevalence differs.

A person suffering from undernutrition may be deficient in vitamins, minerals, and other essential substances that the body needs to function.

Malnutrition can lead to:

  • short-term and long-term health problems
  • slow recovery from injury and illness
  • a higher risk of infection
  • difficulty concentrating at work or school

Certain deficiencies can trigger specific health problems. 

For example a lack of vitamin C can lead to scurvy. Although rare in developed countries, it can develop if a person does not eat a varied diet with plenty of fresh fruits and vegetables.

Older people who drink heavily and people with certain mental health conditions may be particularly at risk. Undernutrition is particularly common in people over 60 years of age. Weight loss in this category approximately doubles the risk of dying.

Malnutrition symptoms

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 be cold
  • the Depression
  • loss of fat, muscle mass, and body tissue
  • a higher risk of getting sick and taking longer to heal
  • longer healing time
  • a higher risk of complications after surgery

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

The causes

Undernutrition can occur for a variety of reasons. 

Low food intake

Some people are undernourished because there is not enough food available or because they have difficulty eating or absorbing vitamins and minerals.

This can happen as a result of:

  • cancer
  • liver disease
  • disorders that cause nausea or make it difficult to eat or swallow
  • taking medications that make it difficult to eat – for example due to nausea

Mental health problems

Undernutrition or malnutrition can affect people with:

  • depression
  • dementia
  • schizophrenia
  • anorexia nervosa

Social and mobility issues

Factors that can affect a person’s eating habits and potentially lead to undernutrition include:

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

Digestive disorders

If the body does not absorb nutrients efficiently, even a healthy diet may not prevent undernutrition.

Here are examples of digestive and gastric conditions that can cause it:

  • Crohn’s disease
  • celiac disease
  • persistent diarrhea, vomiting, or both

Alcohol use disorder

Consuming a lot of alcohol can lead to gastritis or long-term damage to the pancreas. This can make it difficult to digest food, absorb vitamins, and produce hormones that regulate metabolism.

Alcohol also contains calories, so a person may not feel hungry after drinking. She may therefore not be eating enough healthy foods to provide the body with essential nutrients.

Malnutrition and Alzheimer’s disease

Between 20 and 45% of patients with dementia are undernourished and lose weight in the year following the onset of their disease, according to the report entitled “Nutrition and dementia”, from Alzheimer’s Disease International (ADI, February 11, 2014) .

Energy malnutrition results from an imbalance between the body’s intake and needs, leading to tissue loss (including muscle), which has deleterious functional consequences.

In addition, 10% of elderly people at home suffer from undernutrition, and this percentage rises to 30% when they are placed in a retirement home. Finally, this is the case for 70% of hospitalized elderly people.

In people with dementia, malnutrition can be the cause of falls or worsening cognitive impairment.

The Association even suggests that undernutrition is a triggering factor for certain forms of dementia.

The report says that certain measures can be taken to improve the nutrition of patients with dementia. These measures include setting nutritional standards, better monitoring the weight of patients, looking at diet and eating habits regularly, and training the family and professional environment.

This malnutrition may be due to cognitive deficits and loss of autonomy or to an increase in energy expenditure (wandering, hyperactivity).

Protein-energy malnutrition

A disorder characterized by a negative balance of protein and energy, leading to loss of weight and muscle mass. Malnutrition can have several causes:

– Diet that does not meet nutritional needs in protein and energy.

– Poor intestinal absorption.

– Increased nutritional needs following an acute or chronic illness.

– Abnormally large losses caused for example by a nephrotic syndrome or a wound.

It is often observed in elderly people of fragile constitution, living or not in an institution or hospitalized.

Protein-energy malnutrition is retained when, among other things, the elderly person:

– involuntarily loses more than 5 kg.

– Has a body mass index of less than 21 kg/m2.

– Has a Mini Nutritional Assessment test result of less than 17.

The consequences of undernutrition

The consequences are as follows:

  • weightloss;
  • appearance of bedsores;
  • falls and fractures;
  • lowered immune system;
  • bacterial infections (urinary, bronchopulmonary);
  • hospitalization.


It requires:

  • a weight curve;
  • an assessment scale such as the Mini Nutritional Assessment or the Mini Nutritional Assessment Short Form.