Nutrition Diet: How can we define malnutrition? A comprehensive guide

November 1, 2025 •

3 min read

In 2022, nearly 45 million children under 5 were estimated to be wasted, while 37 million were overweight, illustrating the broad scope of the issue. This alarming data shows that how can we define malnutrition is more complex than just a lack of food, encompassing both deficiencies and excesses in nutrient intake.

Quick Summary

Malnutrition is a state of deficiencies, excesses, or imbalances in a person's energy and/or nutrient intake. It includes undernutrition (wasting, stunting, underweight, and micronutrient deficiencies) and overnutrition (overweight, obesity, and related diseases).

Key Points

Broad Definition: Malnutrition includes deficiencies, excesses, or imbalances in nutrient intake, encompassing undernutrition, overnutrition, and micronutrient issues.
Undernutrition Types: Undernutrition manifests as wasting (low weight-for-height), stunting (low height-for-age), and underweight (low weight-for-age), particularly affecting children.
Overnutrition Impact: Excessive intake of calories leads to overweight and obesity, increasing the risk of diet-related noncommunicable diseases like heart disease and diabetes.
Micronutrient Imbalances: Deficiencies or excesses of essential vitamins and minerals can cause severe health problems, such as anemia, blindness, and impaired intellectual capacity.
Diverse Causes: Contributing factors range from poverty and food insecurity to chronic illnesses, mental health conditions, and modern sedentary lifestyles.
Holistic Solutions: Effective solutions involve nutritional education, improving food access, and addressing underlying socioeconomic and health issues.

Understanding the Broad Definition of Malnutrition

To understand how can we define malnutrition, one must move beyond the common perception of starvation and embrace a broader, more inclusive definition used by global health organizations. The World Health Organization (WHO) defines malnutrition as deficiencies, excesses, or imbalances in a person's intake of energy and/or nutrients. This definition recognizes that malnutrition is a multi-faceted issue affecting people globally and encompasses undernutrition (wasting, stunting, underweight), micronutrient-related malnutrition (deficiencies or excesses), and overweight, obesity, and diet-related noncommunicable diseases.

The Three Main Forms of Malnutrition

1. Undernutrition: The classic view

Undernutrition is typically associated with insufficient food intake or poor absorption, leading to health issues, especially in children. Key types include wasting (low weight for height), stunting (low height for age), and underweight (low weight for age).

2. Overnutrition: The modern burden

Overnutrition, consuming excess energy and nutrients, is a significant global health issue. High intake of calorie-dense foods can lead to overweight and obesity, increasing the risk of diet-related NCDs like type 2 diabetes and heart disease. Overnutrition can also result in nutrient imbalances despite sufficient calorie intake.

3. Micronutrient-Related Malnutrition

Micronutrients (vitamins and minerals) are essential for health, even in small amounts. Deficiencies can cause severe problems, such as anemia (iron deficiency), preventable blindness (vitamin A deficiency), and impaired mental function (iodine deficiency). Excessive intake of supplements can also lead to micronutrient toxicity.

Causes, Symptoms, and Diagnosis

Malnutrition is caused by a mix of factors including poverty, chronic health issues, mental health problems, social isolation, and poor dietary choices.

Symptoms of undernutrition include weight loss, lack of appetite, fatigue, weak immunity, and dry skin. Children may show stunted growth or behavioral changes.

Symptoms of overnutrition often involve overweight or obesity, high blood pressure, and signs of metabolic syndrome.

Diagnosis involves physical exams, dietary history, and measurements like BMI. Blood tests can detect micronutrient deficiencies, while tools like the MUAC band help detect wasting in children.

Comparison of Undernutrition and Overnutrition


Feature	Undernutrition	Overnutrition
Primary Cause	Insufficient intake or poor absorption of nutrients.	Excessive intake of calories and nutrients.
Body Weight Impact	Low body weight, wasting, or underweight. Children may experience stunting.	Overweight and obesity due to excessive fat accumulation.
Common Symptoms	Fatigue, weakness, reduced immunity, and delayed wound healing.	High blood pressure, insulin resistance, and increased risk of heart disease.
Vulnerable Populations	Low-income individuals, children, the elderly, and those with chronic diseases.	Individuals with sedentary lifestyles and access to energy-dense, low-nutrient foods.
Nutrient Balance	Overall deficiency in energy and/or specific nutrients like vitamins and minerals.	Excess macronutrients (calories) with potential for micronutrient deficiencies.

Addressing and Treating Malnutrition

Treatment for malnutrition is tailored to its form. Undernutrition often requires therapeutic feeding and supplements. Overnutrition treatment focuses on diet, exercise, and behavioral changes. Treating underlying medical conditions is crucial.

Effective interventions include nutrition education, improving food access, and addressing socioeconomic factors. Promoting breastfeeding, fortifying foods, and ensuring access to clean water and diverse foods are vital for prevention. Organizations like Action Against Hunger offer more information on combating malnutrition.

Conclusion: A Global Health Challenge

Defining malnutrition goes beyond simple food deprivation. It includes deficiencies, excesses, or imbalances in nutrients, covering undernutrition, micronutrient issues, and overnutrition. Tackling malnutrition requires addressing both sides of this spectrum with a holistic approach to ensure optimal health.

Frequently Asked Questions

Undernutrition results from an insufficient intake of nutrients, leading to conditions like wasting and stunting. Overnutrition is caused by consuming an excess of calories, leading to overweight and obesity.

Yes, it is possible. Overnutrition, or excessive calorie intake, is a form of malnutrition, but an individual can be overweight and still have micronutrient deficiencies due to an unbalanced diet.

Common signs include faltering growth, low body weight, lethargy, irritability, and swelling in the legs or stomach. Early detection often involves simple measurements like mid-upper arm circumference (MUAC).

Malnutrition is diagnosed through physical observation, taking a detailed dietary and health history, and anthropometric measurements like BMI. Blood tests may be used to check for specific vitamin and mineral imbalances.

Micronutrient deficiencies can lead to severe health problems, including anemia from lack of iron, blindness from vitamin A deficiency, and cognitive impairment from iodine deficiency.

Treatment varies depending on the type. Undernutrition may require therapeutic feeding and supplements, while overnutrition is managed with dietary changes and increased physical activity. Addressing underlying causes is also key.

The 'double burden' of malnutrition refers to countries experiencing both undernutrition (e.g., stunting and wasting) and overnutrition (overweight and obesity) simultaneously within their population, often affecting different age groups or socioeconomic statuses.