Nutrition Diet: What do you mean by malnutrition?

October 20, 2025 •

4 min read

According to the World Health Organization (WHO), malnutrition affects people in every country, encompassing both undernutrition and overweight/obesity. So, what do you mean by malnutrition? It is defined as deficiencies, excesses, or imbalances in a person's intake of energy and/or nutrients.

Quick Summary

Malnutrition is a state of imbalance caused by either insufficient or excessive intake of nutrients, or an imbalance of them. This broad term covers a spectrum from undernutrition, such as wasting and stunting, to overnutrition, leading to overweight and obesity. It can cause serious health issues and developmental problems if left untreated.

Key Points

Broad Definition: Malnutrition is defined as an imbalance, deficiency, or excess of energy and/or nutrient intake, not just hunger.
Two Main Types: It is classified into undernutrition (insufficient intake) and overnutrition (excessive intake), both of which have serious health consequences.
Forms of Undernutrition: Undernutrition includes wasting, stunting, underweight, and micronutrient deficiencies, which primarily affect vulnerable populations like children.
Forms of Overnutrition: Overnutrition leads to overweight and obesity, increasing the risk of diet-related noncommunicable diseases such as heart disease and diabetes.
Underlying Causes: Factors like poverty, food insecurity, chronic illness, and mental health issues are major contributors to malnutrition globally.
Lifelong Impact: Malnutrition, particularly in early life, can have lasting effects on physical and cognitive development, impacting health and economic productivity.

What is malnutrition?

Malnutrition is not a single condition but a broad term encompassing deficiencies, excesses, or imbalances in a person's intake of energy and/or nutrients. While many people associate it only with undernutrition, which involves a lack of sufficient calories and nutrients, it also includes overnutrition, or the consumption of too many calories. A person can be overweight and still be malnourished if their diet lacks crucial vitamins and minerals. This complex issue is a significant global health challenge, with impacts ranging from stunted growth in children to an increased risk of chronic diseases in adults.

The two main types of malnutrition

The World Health Organization (WHO) and other health bodies classify malnutrition into two broad groups: undernutrition and overnutrition.

Undernutrition

This occurs when a person does not get enough food or nutrients. It includes several distinct forms:

Wasting: Low weight for height, often indicating recent and severe weight loss. In children, it is associated with a higher risk of death if not treated.
Stunting: Low height for age, a result of chronic or recurrent undernutrition that prevents children from reaching their physical and cognitive potential.
Underweight: Low weight for age, which may indicate that a child is either wasted, stunted, or both.
Micronutrient deficiencies or insufficiencies: A lack of essential vitamins and minerals, often referred to as 'hidden hunger.' Common deficiencies include iron, vitamin A, and iodine, which can have profound developmental and health consequences.

Overnutrition

Overnutrition results from the excessive consumption of calories and nutrients, which typically leads to overweight or obesity. This condition is strongly linked to a range of noncommunicable diseases (NCDs).

Overweight and Obesity: An abnormal or excessive fat accumulation that can impair health. This happens when energy intake exceeds energy expenditure.
Diet-related NCDs: Unhealthy diets and poor nutrition are risk factors for diseases like cardiovascular disease, stroke, diabetes, and certain cancers. It is possible for an overweight individual to also have micronutrient deficiencies due to a diet high in energy-dense, but nutrient-poor, processed foods.

Common causes of malnutrition

Malnutrition arises from a complex interplay of factors, varying significantly between and within countries. In low-income areas, limited access to nutritious food is a primary driver, while in developed nations, sedentary lifestyles and cheap, processed foods are major contributors.

Here are some of the most common causes:

Poverty and food insecurity: Lack of financial resources can limit access to adequate and diverse nutrition, impacting both undernutrition and overnutrition.
Limited access to nutritious food: In some regions, fresh and healthy food options are scarce and expensive, while cheap, high-calorie processed foods are readily available.
Chronic health conditions: Diseases that affect appetite, nutrient absorption (e.g., Crohn's disease, celiac disease), or increase caloric needs (e.g., cancer) can lead to malnutrition.
Mental health disorders: Conditions like depression, dementia, and eating disorders can severely disrupt normal eating patterns.
Lifestyle and diet choices: Sedentary habits and diets high in fat, sugar, and salt and low in essential nutrients can cause overnutrition and related deficiencies.
Conflicts and disasters: Humanitarian crises, wars, and climate-related disasters can lead to food shortages and disrupt supply chains, causing widespread hunger.

Signs and symptoms

Symptoms of malnutrition vary depending on whether the individual is experiencing undernutrition or overnutrition. For undernutrition, they often include:

Unintentional weight loss, loss of fat and muscle mass
Fatigue and low energy levels
Irritability and changes in mood
Delayed wound healing and weakened immune function
For children, faltering growth and delayed development

For overnutrition, the signs are typically related to weight gain and associated metabolic issues:

Overweight or obesity
High blood pressure
Insulin resistance
Increased risk of heart disease and diabetes

Diagnosis and treatment

Diagnosis often begins with a physical examination, dietary history, and measurements like Body Mass Index (BMI). Blood tests may be used to identify specific micronutrient deficiencies. Treatment strategies are tailored to the type and severity of malnutrition.

Comparison of treatment approaches


Feature	Undernutrition Treatment	Overnutrition Treatment
Core Strategy	Nutritional supplements, customized refeeding plans, therapeutic foods	Weight loss through diet and lifestyle changes
Severe Cases	Inpatient medical care to manage refeeding syndrome, use of therapeutic milks (F-100) or ready-to-use therapeutic food (RUTF)	Supervised weight management, potential medications or procedures
Dietary Focus	Restoring nutrient and energy intake, increasing protein, and adding vitamins and minerals	Reducing excess calories, sugar, and fat while ensuring adequate micronutrient intake
Associated Care	Addressing underlying infections, providing psychosocial stimulation (especially for children), and ensuring clean water	Managing associated health conditions (e.g., diabetes, hypertension), and providing long-term support systems like counseling

Conclusion

So, what do you mean by malnutrition? It is a complex and multifaceted health issue that extends beyond simple hunger to include overconsumption of certain nutrients. It encompasses both undernutrition, characterized by deficiencies in calories and nutrients, and overnutrition, leading to overweight and obesity. With nearly half of childhood deaths linked to undernutrition and billions of adults living with overweight, the global burden of malnutrition is undeniable. Addressing this requires a holistic approach that includes early intervention, education, improved access to nutritious food, and long-term support systems. By promoting balanced nutrition and addressing the root causes, we can work toward a healthier future for all. For further information and resources, visit the World Health Organization's page on malnutrition.

Frequently Asked Questions

The primary cause depends on the type. Undernutrition is often caused by insufficient food intake due to poverty or limited access. Overnutrition is caused by excessive consumption of energy-dense, nutrient-poor foods alongside a sedentary lifestyle.

Yes, it is possible. This can happen if a person's diet is high in calories but lacks sufficient amounts of essential vitamins and minerals. This condition is sometimes called 'micronutrient undernutrition' and can occur alongside overnutrition.

Diagnosis involves a physical observation, a review of diet and health conditions, and measuring indicators like Body Mass Index (BMI). In some cases, blood tests are used to check for specific micronutrient imbalances.

Early signs of undernutrition often include unintentional weight loss, reduced appetite, and fatigue. In children, faltering growth is a key indicator.

Treatment for severe undernutrition, especially in children, involves controlled refeeding with special therapeutic foods, such as RUTF (ready-to-use therapeutic food) or therapeutic milks, often under close medical supervision to manage risks like refeeding syndrome.

Prevention strategies include promoting a balanced diet rich in fruits, vegetables, whole grains, and lean proteins, as well as nutritional education, and improving food security for vulnerable populations.

The long-term effects of childhood malnutrition can be severe and irreversible, including stunted physical and cognitive development, weakened immune systems, and increased susceptibility to chronic diseases like obesity and diabetes later in life.

Yes. Children are highly vulnerable because of their rapid growth and development, and malnutrition can cause permanent stunting and cognitive delays. While adults also suffer significant health impacts, the consequences for development are most critical in early life.