What Makes a Person Malnourished? Understanding the Causes

November 1, 2025 •

3 min read

According to the World Health Organization, malnutrition includes deficiencies, excesses, or imbalances in a person's intake of energy and/or nutrients. Understanding what makes a person malnourished is crucial for both prevention and treatment, as the condition can stem from a wide range of interconnected factors, affecting individuals of all ages and body weights.

Quick Summary

Malnutrition is not just about being underweight; it results from a dietary imbalance of energy or nutrients. Causes range from poor diet and food insecurity to underlying medical conditions, absorption issues, and social factors affecting access and appetite.

Key Points

Diverse Causes: Malnutrition is caused by a variety of factors, including inadequate nutrient intake, underlying medical conditions, and socioeconomic challenges.
Spectrum of Malnutrition: Malnutrition includes both undernutrition (deficiency) and overnutrition (excess), both of which can lead to severe health problems.
Vulnerable Populations: Children, the elderly, those with chronic illnesses, and individuals in low-income or socially isolated situations are at a higher risk.
Systemic Impact: The consequences of malnutrition affect nearly every organ system, from weakened immunity and muscle mass to cognitive and mental health issues.
Prevention is Key: Prevention involves a multi-pronged approach, including promoting balanced diets, addressing food insecurity, and providing adequate nutritional education.

Malnutrition is a Complex Condition

Malnutrition is a broad term encompassing both undernutrition (not getting enough nutrients) and overnutrition (getting too many nutrients). It is a global issue that can affect anyone, regardless of income level or location. The causes are often multifaceted, involving dietary, environmental, social, and medical factors. Understanding these contributing elements is the first step toward effective prevention and management.

Inadequate Nutrient Intake

Insufficient intake of essential nutrients is a common cause of malnutrition. This can result from:

Food insecurity: Limited access to sufficient and affordable nutritious food, often due to poverty, lack of local resources, or conflict.
Poor dietary choices: Even with food access, a lack of nutritional knowledge or a limited diet can lead to deficiencies. Relying on high-calorie, low-nutrient foods can cause overnutrition alongside micronutrient undernutrition.
Restricted eating: Intentional food restriction, as seen in eating disorders like anorexia, can lead to severe undernutrition.

Underlying Health and Medical Conditions

Various health issues can impede a person's ability to eat, digest, or absorb nutrients.

Digestive and malabsorption issues: Conditions such as Crohn's disease or celiac disease hinder proper nutrient absorption.
Chronic illnesses: Diseases like cancer or HIV/AIDS can increase energy needs or suppress appetite.
Difficulties with eating: Medical conditions causing painful chewing, swallowing problems (dysphagia), or persistent nausea can reduce food intake.
Mental health disorders: Depression, dementia, or anxiety can impact appetite and motivation to eat balanced meals.

Increased Nutritional Requirements and Lifestyle Factors

Certain life stages and situations increase nutrient needs, and if these aren't met, malnutrition can occur.

Pregnancy and breastfeeding: Require additional nutrients for maternal and child health.
Rapid growth in children: Infants and young children need high nutrition for development; inadequate feeding can lead to stunting.
Aging: Older adults may face reduced mobility, appetite loss, or malabsorption, increasing risk.
Excessive alcohol consumption: Can impair digestion, absorption, and suppress appetite.

Environmental and Social Determinants

Social and environmental factors significantly influence malnutrition risk.

Social isolation: Loneliness can reduce motivation to cook and eat.
Limited mobility: Physical limitations can make food shopping and preparation difficult.
Lack of education: Insufficient knowledge about nutrition contributes to poor dietary choices.

Effects of Malnutrition on the Body

Malnutrition impacts nearly all organ systems and can cause various health problems. Effects vary depending on whether it's undernutrition, overnutrition, or micronutrient deficiency.

Undernutrition: Leads to weakened immunity, muscle wasting, fatigue, and impaired development in children.
Overnutrition: Excess fat accumulation increases the risk of chronic diseases like heart disease and diabetes.
Micronutrient deficiencies: Can occur even with sufficient calories, leading to issues like anemia or impaired brain function.

Comparison of Undernutrition and Overnutrition

Understanding the differences between undernutrition and overnutrition clarifies the spectrum of malnutrition:


Feature	Undernutrition	Overnutrition
Cause	Insufficient calories/nutrients, malabsorption, increased requirements.	Excessive calorie intake, high-fat/sugar foods, low physical activity.
Body Composition	Low body weight, loss of fat/muscle mass.	Excess fat accumulation, leading to overweight/obesity.
Health Consequences	Weakened immune system, stunting, increased mortality risk.	Increased risk of chronic non-communicable diseases.
Nutrient Deficiencies	Often widespread deficiencies.	Can occur if diet is low in nutrients despite high calories.
Common Signs	Unintentional weight loss, reduced appetite, fatigue, weakness.	Weight gain, high blood pressure, insulin resistance.

Prevention and Treatment

Preventing malnutrition involves a multi-faceted approach.

Balanced diet: Access to a varied, nutritious diet is fundamental.
Screening and intervention: Early detection in at-risk groups is vital.
Addressing underlying causes: Treating medical or mental health conditions is essential.
Nutritional education: Improves dietary choices.
Food security initiatives: Combat poverty and increase food access.
Healthcare support: Includes supplements and counseling.

Conclusion: The Multifaceted Nature of Malnutrition

Ultimately, what makes a person malnourished is a complex interplay of factors leading to a deficit or excess of necessary nutrients. From socio-economic challenges to personal health issues, the causes are varied and interconnected. Recognizing malnutrition as a spectrum, not a single condition, is key to effective prevention and treatment. Addressing underlying determinants and providing proper nutrition can improve health.

Note: If you or someone you know is at risk of malnutrition, consult a healthcare provider. For resources, visit the World Health Organization website.

Frequently Asked Questions

Yes, a person can be overweight or obese and still suffer from malnutrition. This occurs when their diet provides an excess of calories but is lacking in essential vitamins, minerals, and other key nutrients, a condition sometimes referred to as 'overnutrition'.

Common early signs of malnutrition include unintentional weight loss, reduced appetite, feeling tired and weak all the time, and a prolonged recovery time from illness or wounds. In children, it may also manifest as poor growth or irritability.

Many medical conditions can cause malnutrition by affecting a person's ability to eat, digest, or absorb nutrients. Examples include digestive disorders like Crohn's disease, chronic illnesses like cancer, or issues that cause difficulty swallowing or persistent vomiting.

Poverty contributes significantly to malnutrition by limiting access to affordable, nutritious food. Individuals with low incomes may be forced to rely on cheaper, less nutritious options, leading to nutrient deficiencies despite sufficient calorie intake.

No, malnutrition is a global problem that affects people in both developed and developing nations. While undernutrition is often more prevalent in low-income countries, overnutrition and micronutrient deficiencies are significant issues in wealthier nations.

Childhood malnutrition can have serious and lasting effects, including stunted growth, impaired intellectual development, weakened immune systems, and a higher risk of chronic diseases like obesity and heart disease later in life.

Malnutrition can be prevented through a combination of eating a balanced diet, addressing food insecurity, and providing nutritional education. Early screening and intervention, especially for vulnerable populations, are also crucial.