Understanding Undernutrition: What is an example of undernutrition?

December 11, 2025 •

3 min read

According to the World Health Organization, undernutrition is linked to nearly half of all deaths among children under 5 globally. A prominent and severe example of undernutrition is marasmus, a condition caused by a critical deficiency of protein and calories.

Quick Summary

Undernutrition results from a deficiency of essential nutrients, leading to conditions like marasmus (severe calorie and protein deficit) or kwashiorkor (primarily protein deficit). It can cause visible wasting, stunted growth, and developmental delays, especially in vulnerable populations like children.

Key Points

Marasmus is a severe example: This form of protein-energy malnutrition is caused by a critical deficiency of both calories and protein, leading to extreme wasting.
Undernutrition has many forms: It includes not only marasmus but also kwashiorkor, stunting, wasting, and specific micronutrient deficiencies.
Children are highly vulnerable: Undernutrition severely impacts child growth, cognitive development, and immune function, contributing to high mortality rates.
Causes are complex and varied: The condition often stems from poverty, lack of access to nutritious food, infectious diseases, and malabsorption issues.
Visible and invisible symptoms: Symptoms can be apparent, like extreme thinness (wasting) or swelling (edema), or less obvious, like developmental delays from a single nutrient deficiency.
Treatment requires careful medical management: In severe cases, nutritional rehabilitation must be done slowly to prevent refeeding syndrome, a potentially fatal complication.
Long-term consequences are possible: Some effects, such as stunted growth and cognitive impairment, may not be fully reversible even with treatment.

What Defines Undernutrition?

Undernutrition is a state of severe deficiency of nutrients, encompassing a lack of adequate energy, protein, vitamins, and minerals. While many people associate malnutrition with a simple lack of food, undernutrition is more complex and can result from insufficient intake, poor absorption of nutrients, or increased nutritional demands due to illness. This can manifest in several distinct forms, with symptoms ranging from visible wasting to less obvious developmental impairments. Unlike overnutrition, which is also a form of malnutrition, undernutrition is a deficit rather than an excess. The consequences of undernutrition are serious and can affect physical and cognitive development, immune function, and overall health.

Marasmus: A Classic Example of Undernutrition

Marasmus is arguably one of the most severe and recognizable examples of undernutrition. It is a form of protein-energy malnutrition (PEU) that results from a severe, long-term deficiency of nearly all macronutrients—carbohydrates, fats, and protein. The body, starved for energy, begins to break down its own tissues for fuel, first depleting fat stores and then muscle tissue. This leads to extreme emaciation, visible bones, loose skin, and in children, a gaunt face. Stunted growth, weakness, and lethargy are also common. Marasmus is particularly dangerous in infants and young children with high nutritional needs. Early weaning without proper nutritional alternatives can trigger this condition.

The Spectrum of Undernutrition

Beyond severe cases like marasmus, undernutrition includes wasting, stunting, underweight, and micronutrient deficiencies.

Protein-Energy Undernutrition (PEU)

PEU covers conditions from inadequate calories and protein. Another major form is kwashiorkor, which differs from marasmus in key ways:


Feature	Marasmus	Kwashiorkor
Primary Deficiency	Severe deficiency in nearly all macronutrients (calories, protein, fat).	Severe deficiency primarily in protein, with adequate or near-adequate calorie intake.
Appearance	Wasted, skeletal, and emaciated.	Puffy or swollen appearance (edema), especially in the face and limbs.
Body Composition	Loss of both muscle mass and subcutaneous fat.	Muscle wasting is present, but fluid retention hides it. Subcutaneous fat may be preserved.
Belly	The belly may appear distended, but often the person is thin all over.	A distended, protruding belly is a classic symptom due to fluid retention.

Micronutrient Deficiencies

Undernutrition can also be a lack of specific vitamins or minerals, known as “hidden hunger”. Examples include:

Iron Deficiency Anemia: Insufficient iron causes fatigue, weakness, and pale skin due to low hemoglobin. It can cause developmental delays in children.
Vitamin A Deficiency: A leading cause of preventable blindness and weakened immunity globally.
Iodine Deficiency: Can lead to thyroid issues like goiter and impaired cognitive development, especially in children.

Causes and Risk Factors

Undernutrition is often caused by a combination of factors:

Poverty and Food Insecurity: Limited access to nutritious food due to financial constraints.
Infectious Diseases: Illnesses like diarrhea and measles can cause nutrient loss and increase needs.
Malabsorption Disorders: Conditions like IBD or celiac disease hinder nutrient absorption.
Inadequate Infant Feeding: Improper breastfeeding or weaning can lead to deficiencies.
Mental Health: Conditions like anorexia or depression can impact appetite.
Aging: Older adults may have reduced appetite and mobility issues affecting diet.

Diagnosis and Treatment

Diagnosis involves physical exams, body measurements, and blood tests. Treatment is a gradual, multi-stage process due to the risk of refeeding syndrome. Phases include stabilization, nutritional rehabilitation with specialized formulas, and follow-up to prevent recurrence. For more information on global malnutrition prevention, visit the World Health Organization website.

Conclusion

Undernutrition is a devastating global health issue with diverse forms, from severe marasmus and kwashiorkor to micronutrient deficiencies. It stems from complex socioeconomic, environmental, and health factors. Recognizing these varied examples of undernutrition is vital for effective diagnosis, treatment, and prevention efforts to improve health outcomes worldwide.

Frequently Asked Questions

Marasmus is one of the most severe examples of undernutrition, resulting from a critical deficiency of all major macronutrients, including calories and protein, which leads to severe wasting of body fat and muscle.

No, malnutrition is a broader term that encompasses both undernutrition (deficient intake or absorption) and overnutrition (excessive intake). Undernutrition is a specific form of malnutrition.

The four main sub-forms of undernutrition are wasting (low weight for height), stunting (low height for age), underweight (low weight for age), and micronutrient deficiencies.

Yes, it is possible for a person to be overweight but still undernourished. This happens when they consume enough calories to be overweight or obese but their diet lacks essential vitamins and minerals, leading to micronutrient deficiencies.

Kwashiorkor is primarily caused by a severe deficiency of protein, often occurring when a child is weaned from breastfeeding onto a diet that is high in carbohydrates but lacks protein.

Stunting is a condition resulting from chronic or recurrent undernutrition, leading to low height for a person's age. It is often caused by poor socioeconomic conditions, inadequate feeding, and frequent illness in early life.

Iron deficiency is an example of a micronutrient undernutrition. A lack of sufficient iron prevents the body from producing enough hemoglobin, causing anemia, which leads to symptoms like fatigue, weakness, and developmental delays.