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Malnutrition alert!

A real public health issue, undernutrition affects nearly 2 million French people. Focus on the causes and dangers of this silent disease that is still too trivialized.

What is undernutrition?

Malnutrition affects nearly 2 million French people, including the elderly, but also adults and children. It corresponds to a nutritional imbalance that may result from insufficient food intake, increased energy loss by certain diseases or an increase in the body’s needs not covered by food. This imbalance causes weight loss important of the malnourished person with a reduction in fatty tissue and muscle mass.

The diagnosis of undernutrition is made in the event of a body mass index of less than 18.5 kg/m2 in adults (and less than 21 kg/m2 in those over 70). However, contrary to what one might think, undernutrition is not always synonymous with weight loss. A person with a normal or high body mass index may also be undernourished. In practice, we therefore consider that a patient suffers from undernutrition if his weight loss is greater than or equal to 5% in one month or greater than or equal to 10% in six months.

To know ! Undernutrition is a form of malnutrition. Malnutrition encompasses deficiencies, excesses or imbalances in a person’s energy and/or nutritional intake.

How does she settle in?

The nutritional imbalance observed in the malnourished person can be explained by three sometimes associated reasons:

  1. A decrease in food intake
  2. Increased loss of energy and protein from the body during certain illnesses (such as Covid-19)
  3. An increase in energy needs not covered by food.

Loss of appetite is the main cause of reduced food intake. It can itself be linked to various reasons, including social isolation, family or financial difficulties, a disability, a restrictive diet, depression, etc. Chronic digestive disorders, pain in the oral sphere (gingivitis, mycosis of mouth, lack of teeth, unsuitable braces,) or quite simply difficulty swallowing can also explain a loss of appetite.

In addition, certain infectious diseases (tuberculosis, HIV) can promote energy loss. Extensive burns or wounds also increase the energy needs of the body. Certain specific situations such as taking medication (cancer chemotherapy, neuroleptics, etc.) or major surgery (surgery for obesity, for example) also promote undernutrition.

To know ! It is estimated that the prevalence of undernutrition during cancer is around 40% and up to 70% for certain cancers such as pancreatic cancer. Malnutrition is also a frequent complication of digestive cancers (mouth, throat, esophagus, stomach, colon).

Lastly, physical endurance activities can trigger undernutrition if food intake does not compensate for energy losses.

Why is undernutrition dangerous for health?

The undernutrition is not without danger for the state of health of the person concerned. It is the muscles, protein reserves, which will be the most affected. However, when it becomes too large, muscle wasting causes many complications with :

  • Mechanical consequences (risk of falling, loss of mobility, dependence).
  • Significant psychological repercussions (irritability, depressive tendency, difficulty concentrating and memory problems).
  • Slower emptying of the stomach after meals with poor digestion and constipation.
  • A lack of healing after surgery or after a wound.
  • Hormonal imbalance with amenorrhea, delayed puberty, decreased libido and fertility.
  • A tendency to chilliness due to dysregulation of thermoregulation.
  • A decrease in quality of life.

Added to this is a decrease in natural defenses that can lead to new, more severe infections, complications and even the death of the malnourished person.

To know ! Malnutrition multiplies by 4 the risk of mortality in the elderly and aggravates pre-existing diseases through complications, longer convalescence, and even new hospitalizations.

This shows how much malnutrition can have serious consequences on the state of health of the person who suffers from it. A real threat to the autonomy and life expectancy of the population, undernutrition must therefore be the subject of very particular vigilance. If they are deciphered in time, certain warning signs will prevent their appearance and development in an elderly person, a young child or a sick or hospitalized person.

Published on June 13, 2017 by Lucie B., Biologist specialized in E-health and updated on September 14, 2022 by Déborah L., Doctor of Pharmacy.


– Understanding undernutrition. Accessed September 14, 2022.