What diseases can you get from protein deficiency? An in-depth nutritional guide

October 20, 2025 •

4 min read

According to UNICEF, undernutrition is responsible for at least one-third of deaths in young children worldwide. A significant contributor to this statistic is severe protein deficiency, which can lead to life-threatening diseases and long-term health complications if left unaddressed.

Quick Summary

Protein deficiency can cause severe malnutrition syndromes like kwashiorkor and marasmus. It also leads to a weakened immune system, edema, loss of muscle mass, stunted growth, and various skin and hair issues due to impaired bodily functions.

Key Points

Kwashiorkor is a severe form of malnutrition: This disease is caused primarily by protein deficiency and is characterized by edema (swelling), particularly in the limbs and abdomen.
Marasmus is caused by a lack of all macronutrients: Resulting from general starvation, this condition causes severe muscle wasting and emaciation, giving the individual a shrunken appearance.
Protein deficiency weakens the immune system: A shortage of protein impairs the body’s ability to produce antibodies and immune cells, making it more vulnerable to infections.
Chronic low protein leads to edema: Low levels of the blood protein albumin can disrupt the body's fluid balance, causing swelling in the extremities.
Muscle mass is lost during deficiency: The body breaks down its own muscle tissue to obtain amino acids for essential functions when dietary protein is insufficient, causing weakness and atrophy.
Long-term effects include stunted growth and cognitive issues: In children, protein deficiency can lead to irreversible stunting and delayed intellectual development. Adults may experience fatigue and mood changes due to impaired brain function.
Prevention is possible through a balanced diet: A varied intake of protein from sources like lean meats, fish, eggs, dairy, and legumes is the best way to prevent deficiency.

Protein is one of the most critical macronutrients, essential for virtually every bodily function, from building and repairing tissues to producing hormones and enzymes. When dietary protein intake is insufficient, the body begins to break down muscle and other tissues to meet its needs, leading to a host of debilitating health problems. In severe cases, this can result in life-threatening conditions like Kwashiorkor and Marasmus.

The Severe Consequences of Protein Malnutrition

Kwashiorkor and Marasmus are the two most severe forms of protein-energy malnutrition (PEM), primarily affecting children in developing countries where food scarcity is a major issue. However, milder forms can impact people of all ages globally, including the elderly, those with eating disorders, or individuals with chronic illnesses.

Kwashiorkor

Named from the Ga language of Ghana meaning “the sickness the baby gets when the new baby comes,” Kwashiorkor typically affects toddlers who are abruptly weaned from breastfeeding to a diet high in carbohydrates but critically low in protein. A primary symptom is edema, or swelling, particularly in the ankles, feet, face, and abdomen, which can mask severe malnutrition.

Other symptoms and complications of Kwashiorkor include:

Enlarged, fatty liver: Due to the body's inability to synthesize lipoproteins for fat transport.
Changes to hair and skin: Hair can become brittle, dry, and lose its pigment, while skin may develop dry, peeling patches or ulcers.
Fatigue and apathy: Children may exhibit a lack of energy, irritability, and general listlessness.
Stunted growth: Physical growth is severely hampered.
Weakened immune system: Reduced antibodies and immune cell production make the body highly vulnerable to infections.

Marasmus

Unlike Kwashiorkor, Marasmus results from a severe deficiency of all macronutrients—protein, carbohydrates, and fats. This condition is characterized by a visibly emaciated, shrunken, and wasted appearance, with a noticeable loss of both muscle mass and subcutaneous fat.

Symptoms of Marasmus often include:

Extreme weight loss: Body weight can drop below 60% of the normal weight for age.
Stunted growth: Severe growth retardation is a common and lasting effect.
Wasting: Loose folds of skin hang from the body due to the severe loss of muscle and fat.
Behavioral changes: Apathy, irritability, and a general lack of enthusiasm are common.
Compromised immune function: Like Kwashiorkor, Marasmus severely impairs the immune system, leaving the individual susceptible to life-threatening infections.

Chronic and Subclinical Effects of Protein Deficiency

Even in the absence of severe PEM, chronic low protein intake can lead to a variety of less obvious but still harmful health issues. The body's constant struggle to source amino acids for vital functions takes a toll on multiple systems.

Compromised Immune System: Proteins are the building blocks for antibodies and other immune-signaling molecules. Inadequate protein intake can impair the immune system's ability to produce these, resulting in more frequent and severe infections.
Edema (Fluid Retention): Albumin, a key blood protein, is responsible for maintaining the fluid balance in the body. Low protein levels lead to reduced albumin, causing fluid to leak into surrounding tissues and causing swelling, often in the feet, ankles, and abdomen.
Hair, Skin, and Nail Problems: The structural proteins keratin, collagen, and elastin are dependent on a steady supply of dietary protein. A deficiency can manifest as brittle nails, thinning hair, hair loss, and dry, flaky skin.
Muscle Atrophy and Weakness: When the body doesn't get enough protein from food, it begins to break down muscle tissue to supply amino acids for more critical processes. This leads to a gradual loss of muscle mass, reduced strength, and overall fatigue.
Bone Health Issues: Collagen, the primary protein in bones, provides a flexible framework that makes them strong. Inadequate protein intake can weaken this framework, increasing the risk of fractures and potentially contributing to conditions like osteoporosis over time.
Brain Fog and Mood Changes: Neurotransmitters like dopamine and serotonin are synthesized from amino acids. A protein-deficient diet can hinder their production, potentially leading to mood swings, irritability, anxiety, and poor concentration.

Comparison of Kwashiorkor and Marasmus


Feature	Kwashiorkor	Marasmus
Primary Deficiency	Severe protein deficiency, often with relatively adequate caloric intake.	Deficiency of all macronutrients: protein, carbohydrates, and fats.
Appearance	Bloated or swollen appearance (edema), especially in the abdomen and limbs, masking severe malnutrition.	Wasted, emaciated appearance, with extreme loss of muscle and body fat.
Underlying Cause	Transition from breastfeeding to a low-protein, high-carbohydrate diet.	Overall starvation and chronic lack of food.
Key Symptoms	Edema, fatty liver, dry/brittle hair, skin lesions, apathy.	Visible bones, severe weight loss, loose skin folds, weakness, stunted growth.
Prognosis	Can be life-threatening due to infection, dehydration, or liver failure.	Life-threatening without treatment; can result in permanent developmental issues.

Preventing and Addressing Protein Deficiency

The best approach to preventing protein deficiency is a varied and balanced diet that includes sufficient protein from both animal and plant sources. For more information on balancing your diet and protein sources, Harvard's T.H. Chan School of Public Health offers valuable insights on protein intake. A diet rich in legumes, nuts, seeds, lean meats, fish, and dairy can help most healthy individuals meet their daily requirements.

Individuals in high-risk categories, such as the elderly or those with chronic illnesses, may require a more tailored approach and possibly supplementation under medical supervision. In cases of severe malnutrition, such as Kwashiorkor or Marasmus, hospitalization and a carefully managed refeeding process are essential to avoid complications like refeeding syndrome.

Conclusion

Protein deficiency is far more than simply being hungry; it is a complex nutritional disorder with potentially severe and life-altering consequences. From the devastating effects of Kwashiorkor and Marasmus in young children to the myriad of chronic health issues in adults, inadequate protein intake compromises the body's fundamental functions. Recognizing the signs and ensuring a consistent and varied supply of protein-rich foods is vital for preventing these diseases, supporting a robust immune system, and maintaining overall health throughout life.

Frequently Asked Questions

The most severe diseases are Kwashiorkor and Marasmus. Kwashiorkor is primarily a protein deficiency causing edema, while Marasmus is a deficiency of all macronutrients leading to severe wasting.

Yes, protein deficiency significantly weakens the immune system. Proteins are required to create antibodies and other immune components, so a lack of protein makes the body more susceptible to infections and slows wound healing.

Yes, a common sign of protein deficiency is edema, or swelling due to fluid retention. This is caused by low levels of the blood protein albumin, which is necessary for maintaining fluid balance.

While severe deficiency is rare in developed countries, high-risk groups include children in developing nations, the elderly, individuals with chronic illnesses, those with eating disorders, and some vegetarians or vegans with poorly planned diets.

When the body lacks sufficient dietary protein, it cannibalizes its own muscle tissue to access amino acids for more vital functions. This process leads to muscle wasting, weakness, and fatigue.

Yes, low protein intake can affect mood. Many neurotransmitters, which regulate brain function, are made from amino acids. A deficiency can lead to mood swings, irritability, anxiety, and poor focus.

To prevent a protein deficiency, ensure you eat a balanced diet that includes a variety of protein sources like lean meats, fish, eggs, dairy, legumes, nuts, and seeds throughout the day.