Understanding What is PEM Sickness: Causes, Symptoms, and Treatment

October 8, 2025 •

4 min read

According to the World Health Organization, malnutrition is the single gravest threat to the world's public health, and is by far the biggest contributor to child mortality. An especially severe form of this condition is often referred to as PEM sickness, or Protein-Energy Malnutrition, which results from a severe deficiency of dietary protein and/or calories.

Quick Summary

Protein-energy malnutrition (PEM) arises from a severe lack of protein and energy intake, affecting individuals across different ages, particularly young children. This condition manifests in distinct forms, like marasmus and kwashiorkor, and requires cautious nutritional rehabilitation to reverse its damaging effects on body weight, tissue, and overall function.

Key Points

Definition: PEM, or Protein-Energy Malnutrition, is a severe nutritional deficiency caused by inadequate protein and calorie intake.
Two Major Types: It presents as either marasmus (severe wasting) or kwashiorkor (edema and swelling), and sometimes a combination of both.
Distinct Symptoms: Marasmus is marked by extreme thinness and muscle loss, while kwashiorkor is defined by characteristic swelling and hair changes.
Treatment Approach: Involves cautious nutritional rehabilitation with high-calorie, high-protein foods to avoid refeeding syndrome.
Serious Complications: Untreated PEM can lead to severe health issues, including heart failure, infections, and permanent cognitive impairment.
Prevention: Prevention focuses on adequate nutrition, promoting breastfeeding, and addressing underlying socioeconomic factors like poverty.
Not ME/CFS: It's crucial not to confuse Protein-Energy Malnutrition with Post-Exertional Malaise (PEM), a different condition associated with ME/CFS.

What Is Protein-Energy Malnutrition (PEM)?

Protein-Energy Malnutrition (PEM), or protein-calorie malnutrition (PCM), is a critical nutritional deficiency that occurs when an individual's diet lacks sufficient protein and calories to meet metabolic demands. While most commonly associated with children in developing nations, it can affect adults with chronic illnesses, eating disorders, or limited access to food. PEM should not be confused with Post-Exertional Malaise (PEM), which is a different condition linked to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). A proper nutrition diet is the cornerstone of preventing and treating this serious health issue.

The Distinct Types of PEM

PEM is categorized into several types based on the specific nutrient deficiencies, with the most severe forms being kwashiorkor and marasmus.

Marasmus

Cause: Results from a severe deficiency of all major nutrients, particularly total calories and protein.
Appearance: Characterized by extreme emaciation, with visible muscle wasting and depletion of body fat stores. Children with marasmus may have a wrinkled, "old man" or "monkey" face due to the loss of fat pads in the cheeks.
Key Feature: Lacks the generalized edema found in kwashiorkor.

Kwashiorkor

Cause: Primarily caused by a severe dietary protein deficiency, often occurring in children who have been weaned from breast milk and fed a carbohydrate-heavy diet.
Appearance: The most defining symptom is edema, or swelling, which typically affects the face ("moon face"), abdomen ("pot belly" from ascites), and limbs.
Key Features: Other symptoms include dry, flaky skin, discolored and thinning hair, apathy, and an enlarged liver.

Marasmic-Kwashiorkor

Cause: A mixed form of severe malnutrition that exhibits characteristics of both marasmus and kwashiorkor.
Appearance: Combines the severe muscle wasting and emaciation of marasmus with the edema and other signs of kwashiorkor.

Signs and Symptoms of PEM

The signs of PEM can range from mild to severe and manifest differently depending on the type and age of the affected individual.

Common Symptoms in Children

Poor weight gain and stunted growth.
Irritability and apathy.
Diarrhea.
Recurrent infections due to a weakened immune system.
Thin, dry, and discolored hair.

Common Symptoms in Adults

Significant weight loss (which may be hidden by edema).
Muscle wasting and overall weakness.
Non-healing wounds and decubitus ulcers.
Listlessness and fatigue.
Feeling constantly cold.

Diagnosis and Treatment

Diagnosing PEM involves a clinical examination, a nutritional history review, and an assessment of weight and height. Lab tests can confirm deficiencies and complications. Treatment is complex and requires careful management to prevent refeeding syndrome, a potentially fatal shift in fluid and electrolytes that can occur with overzealous nutritional support. The World Health Organization (WHO) outlines a phased approach to recovery, starting with stabilization before moving to nutritional rehabilitation.

Nutritional Rehabilitation

The diet is the main tool for treating PEM and must be implemented cautiously. Key dietary principles include:

High-Calorie Intake: Energy-giving foods like cereals (oats, rice) and starchy sources are crucial for restoring energy.
High-Protein Intake: Lean meats, fish, eggs, dairy, and legumes are essential for tissue repair and immune function.
Micronutrient Repletion: Supplementation with vital vitamins (A, C, B-complex) and minerals (iron, zinc, calcium) is necessary, as deficiencies are common.
Frequent, Small Meals: For severe cases, starting with small, frequent, and easily digestible meals prevents overwhelming the digestive system.


Comparison of Kwashiorkor and Marasmus	Feature	Kwashiorkor	Marasmus
Primary Deficiency	Primarily protein	Calories and all major nutrients
Key Symptom	Edema (swelling)	Extreme emaciation, severe muscle wasting
Subcutaneous Fat	Maintained or even gained	Severely depleted
Onset Age	Often between 1 and 4 years old (after weaning)	Typically under 1 year old
Body Weight	May not appear significantly low due to edema	Drastically low weight for height
Face Appearance	"Moon face" due to edema	"Monkey" or "old man" face due to fat loss

Complications of PEM

If not properly treated, PEM can lead to severe, life-threatening complications.

Hypoglycemia and Hypothermia: Critically low blood sugar and body temperature are common and dangerous, especially in severe cases.
Infections: A severely weakened immune system makes individuals highly susceptible to various infections, including sepsis.
Organ Failure: Impaired function of the heart, liver, and kidneys is a serious risk.
Neurological Damage: Lack of proper nutrition, especially in children, can lead to permanent neurological deficits and cognitive impairments.
Growth Failure: Chronic malnutrition can result in stunting (low height-for-age) and developmental delays.

Preventing PEM

Prevention strategies are critical for reducing the incidence of PEM, particularly in vulnerable populations.

Balanced Diet: Consuming a variety of food groups—including whole grains, proteins, fruits, and vegetables—is fundamental.
Breastfeeding: For infants, breastfeeding provides the best nutrition for growth and is a key preventative measure against PEM.
Nutritional Education: Ensuring communities have knowledge about proper nutrition and food preparation can significantly reduce the risk.
Addressing Underlying Issues: Tackling systemic problems like poverty, food insecurity, and chronic infections is essential for long-term prevention.
Medical Follow-up: Early detection and treatment of any health issues that may impact nutrient absorption can prevent the onset of PEM.

Conclusion

PEM sickness, or Protein-Energy Malnutrition, is a serious and potentially fatal condition that stems from a severe deficiency of protein and calories. By understanding its distinct forms, marasmus and kwashiorkor, and the critical signs, we can recognize the need for prompt and careful medical intervention. A managed nutritional diet plan, focused on high-calorie and high-protein foods rich in micronutrients, is key to reversing the effects and preventing long-term complications. Education, addressing societal disparities, and seeking medical help at the earliest signs are vital steps toward combating this global health threat.

For more detailed information on managing severe malnutrition, the World Health Organization provides comprehensive guidelines.

Frequently Asked Questions

The primary cause of PEM sickness, or Protein-Energy Malnutrition, is an inadequate intake of dietary protein and calories to meet the body's energy and nutrient needs.

Marasmus is characterized by severe wasting and emaciation due to a deficiency in both calories and protein, while kwashiorkor is defined by edema and swelling resulting primarily from a lack of protein.

While anyone with poor nutritional intake is at risk, young children in developing countries are most commonly affected. Adults with chronic illnesses, eating disorders, or limited food access can also develop PEM.

Refeeding syndrome is a dangerous metabolic shift that can occur when severely malnourished individuals are given rapid, high-calorie refeeding. It can cause fluid overload and critical electrolyte imbalances, which is why nutritional rehabilitation must be done slowly and cautiously.

Yes, if left untreated, PEM can lead to long-term and permanent health problems, including cognitive deficits, stunted growth, weakened immunity, and organ damage.

Prevention involves ensuring a balanced diet with sufficient protein, calories, vitamins, and minerals. Promoting breastfeeding for infants, providing nutritional education, and addressing food insecurity are also key preventative measures.

Treatment for PEM involves a gradual and cautious nutritional rehabilitation plan, focusing on re-establishing a balance of calories, protein, and micronutrients. In severe cases, medical supervision is essential to manage complications like infections and refeeding syndrome.

No, PEM can be confused with Post-Exertional Malaise, an acronym for a symptom associated with Chronic Fatigue Syndrome. Protein-Energy Malnutrition is a nutritional disorder, whereas Post-Exertional Malaise is a pathological condition unrelated to diet.