What are the two types of acute malnutrition?: Marasmus and Kwashiorkor Explained

October 16, 2025 •

4 min read

According to UNICEF, WHO, and the World Bank, in 2024, approximately 42.8 million children under five were affected by wasting, a key sign of acute malnutrition. Understanding what are the two types of acute malnutrition—Marasmus and Kwashiorkor—is critical for recognizing and addressing these life-threatening conditions. These forms arise from deficiencies in macro and micronutrients, primarily impacting children in low- and middle-income countries.

Quick Summary

An in-depth guide covering Marasmus and Kwashiorkor, the two primary forms of acute malnutrition. This summary explores their distinct symptoms, underlying causes, diagnostic methods, and standard treatment protocols.

Key Points

Two Primary Forms: Acute malnutrition presents mainly as Marasmus (severe wasting) and Kwashiorkor (edema).
Marasmus is Calorie Deficiency: It is caused by an extreme lack of all macronutrients, leading to emaciation and a 'skin and bones' appearance.
Kwashiorkor is Protein Deficiency: This form is primarily caused by insufficient protein, resulting in fluid retention (edema) that can mask underlying wasting.
Marasmic-Kwashiorkor: A hybrid form of acute malnutrition exists, combining the symptoms of both wasting and edema.
Diagnosis is Clinical: Healthcare providers use a combination of anthropometric measurements (WHZ, MUAC) and physical signs like bilateral edema for diagnosis.
Treatment is Phased: Management requires careful, staged nutritional rehabilitation to avoid refeeding syndrome and address infections.
Long-Term Consequences: Surviving acute malnutrition, especially in childhood, can lead to persistent neurodevelopmental, cognitive, and behavioral issues.

Unpacking the Crisis of Acute Malnutrition

Acute malnutrition, often a consequence of recent or severe nutritional deficiency, results in rapid weight loss and severe physiological disturbances. While chronic malnutrition, or stunting, develops over a long period, acute malnutrition, also known as wasting, indicates a current, severe energy and nutrient deficit. It is a critical public health issue that significantly increases the risk of mortality, especially among young children. The two most severe forms of acute malnutrition present with very different clinical features, demanding specific diagnostic criteria and treatment approaches.

Marasmus: The 'Wasting Away' Malnutrition

Marasmus, derived from the Greek word for 'wasting away,' is the most common form of acute malnutrition and results from a severe, prolonged deficiency in all macronutrients: carbohydrates, proteins, and fats. This total energy deficit forces the body to consume its own tissues for energy, leading to extreme weight loss and a visibly emaciated appearance.

Symptoms of Marasmus

Severe Wasting: Marked depletion of muscle and subcutaneous fat, giving the appearance of 'skin and bones'.
Emaciation: A gaunt, aged, or 'old man' appearance, particularly in the face due to loss of fat.
Growth Retardation: Severely stunted physical development in children.
Lethargy and Irritability: Low energy levels and apathy are common.
Thinning Hair: Hair may become dry, brittle, and sparse.
Dry, Loose Skin: The skin often hangs in folds due to the loss of underlying tissue.
Depleted Immune System: Increased susceptibility to infections.

Kwashiorkor: The 'Swollen Belly' Malnutrition

Unlike Marasmus, Kwashiorkor is predominantly a protein deficiency, occurring even when overall calorie intake is somewhat adequate, often from a diet heavy in carbohydrates. It is characterized by edema (swelling) caused by fluid retention, which can mask the true extent of weight loss. This edema results from a lack of protein, specifically albumin, in the blood, which decreases intravascular oncotic pressure.

Symptoms of Kwashiorkor

Bilateral Pitting Edema: Swelling in both feet is the hallmark sign. In severe cases, edema can affect the legs, hands, arms, and face.
Distended Abdomen: A 'pot belly' caused by edema and muscle wasting, a misleading sign of being well-fed.
Skin and Hair Changes: Dermatosis resembling burns, peeling skin, and changes in hair color and texture (the 'flag sign') are common.
Enlarged, Fatty Liver: A sign of impaired protein synthesis and lipid transport.
Extreme Irritability and Apathy: Often lethargic, passive, and irritable.
Failure to Grow: Stunted growth despite the misleading weight from edema.

Marasmic-Kwashiorkor: A Combination of Both

Some individuals present with a mixed picture, combining the clinical features of both Marasmus and Kwashiorkor. These patients exhibit both severe wasting and bilateral pitting edema, indicating a severe deficiency of both total calories and protein. This hybrid form is also associated with high mortality rates.

Comparison of Marasmus and Kwashiorkor


Feature	Marasmus	Kwashiorkor
Primary Cause	Severe deficiency of all macronutrients (calories, protein, fat).	Predominant deficiency of protein, with relatively sufficient carbohydrate intake.
Key Clinical Sign	Extreme wasting and emaciation, visible loss of fat and muscle.	Bilateral pitting edema (swelling).
Appearance	'Skin and bones' look, visibly underweight, gaunt face.	Swollen abdomen and extremities, 'moon face,' often hides underlying wasting.
Body Composition	Near-complete loss of subcutaneous fat and muscle mass.	Subcutaneous fat may be preserved, but significant muscle wasting occurs.
Appetite	Often ravenous hunger, but may have a reduced appetite.	Typically poor appetite or anorexia.
Hair	Dry, thin, and brittle.	Thin, sparse, depigmented hair (the 'flag sign').
Skin	Dry, loose, and wrinkled.	Lesions, peeling skin, and hyper- or hypopigmentation.
Mental State	May be irritable, but often alert.	Apathetic, irritable, and withdrawn.

Diagnosis and Management of Acute Malnutrition

Early and accurate diagnosis is essential for effective treatment. Health workers use standardized anthropometric measurements, such as weight-for-height/length (WHZ) and mid-upper arm circumference (MUAC), alongside clinical examinations for bilateral edema.

Diagnostic Criteria

Weight-for-Height/Length: WHZ score more than -3 standard deviations below the median indicates severe acute malnutrition (SAM).
Mid-Upper Arm Circumference (MUAC): A MUAC of less than 115mm is a diagnostic criterion for SAM in children aged 6–59 months.
Clinical Signs: The presence of bilateral pitting edema is an immediate sign of SAM.

Treatment Protocols

According to WHO guidelines, treatment follows a phased approach to carefully manage refeeding syndrome, a potentially fatal complication.

Initial Stabilization Phase: Focuses on treating immediate, life-threatening issues like hypoglycemia, hypothermia, dehydration, and infections.
Rehabilitation Phase: Gradual reintroduction of therapeutic foods, such as ready-to-use therapeutic foods (RUTF), to promote catch-up growth.
Follow-up Phase: Ongoing monitoring and nutritional education for caregivers to prevent relapse.

Long-Term Impact of Acute Malnutrition

While acute malnutrition is a short-term crisis, its effects can be devastating and long-lasting, especially in childhood. Research has linked early childhood malnutrition to long-term cognitive, behavioral, and developmental problems. Survivors may experience lower academic achievement, impaired cognition, and lower self-esteem into adulthood. These lasting effects can perpetuate a cycle of poverty and poor health across generations. Interventions must address not only the immediate nutritional needs but also the long-term developmental support required for survivors.

Conclusion

Acute malnutrition manifests primarily in two distinct forms, Marasmus and Kwashiorkor, each with unique clinical signs resulting from different nutritional deficiencies. Marasmus is characterized by severe wasting due to a total calorie deficit, while Kwashiorkor is defined by edema resulting from severe protein deficiency. Understanding these differences is crucial for proper diagnosis and effective management. With millions of children affected globally, recognizing the signs and implementing appropriate treatment protocols is a vital step in reducing childhood mortality and mitigating the devastating long-term developmental consequences of this preventable crisis. Targeted nutritional and medical care, especially in early childhood, is the best strategy to improve outcomes for survivors of acute malnutrition. For more comprehensive information on treatment guidelines, consult resources from authoritative sources like the National Institutes of Health (NIH).

Frequently Asked Questions

The key difference is the presence of edema. Marasmus is characterized by severe wasting and emaciation, while Kwashiorkor's defining symptom is bilateral pitting edema, or swelling due to fluid retention.

Yes, a person can have a combined form called Marasmic-Kwashiorkor. This condition shows a mix of symptoms, including both severe wasting and edema.

Marasmus is caused by a severe deficiency of all macronutrients (calories, protein, and fat). Kwashiorkor, however, is primarily caused by a severe protein deficiency, even if calorie intake is maintained, often from a carbohydrate-heavy diet.

Diagnosis involves a clinical examination and anthropometric measurements. Key indicators include a very low weight-for-height/length (<-3 SD), a low mid-upper arm circumference (MUAC < 115mm in children), and the presence of bilateral edema.

Treatment is conducted in phases, starting with stabilizing the patient by addressing immediate complications like hypoglycemia and infections. This is followed by gradual nutritional rehabilitation using specialized therapeutic foods to promote catch-up growth.

Refeeding syndrome is a dangerous metabolic shift that can occur when severely malnourished individuals are fed too aggressively. It can lead to fatal complications like heart failure and requires careful medical supervision during the initial treatment phase.

While treatment can reverse many of the immediate health crises, some long-term effects, particularly neurodevelopmental and cognitive impairments, may not be fully reversible, especially in children. Long-term support is often necessary.