Nutrition Diet: Understanding What Are the Grades of Malnutrition?

October 16, 2025 •

3 min read

According to the World Health Organization, nearly half of deaths among children under 5 years of age are linked to undernutrition. Understanding what are the grades of malnutrition? is a critical first step in determining the severity of a nutritional imbalance and implementing the most effective nutritional diet and treatment plan.

Quick Summary

This article explains the various grades of malnutrition, detailing how severity is classified using different systems. It covers the World Health Organization's (WHO) approach for children, assessment methods for adults, and the specific indicators used for accurate diagnosis.

Key Points

Severity is Graded: Malnutrition is classified into grades like mild, moderate, and severe to guide treatment, based on standardized assessment criteria.
WHO Z-Score System: The World Health Organization uses z-scores to grade malnutrition in children, measuring how far weight or height deviates from a healthy reference.
Key Child Indicators: In children, Severe Acute Malnutrition (SAM) is identified by very low weight-for-height, low Mid-Upper Arm Circumference (MUAC), or bilateral edema.
Wasting vs. Stunting: Wasting is acute (low weight for height), and stunting is chronic (low height for age), representing different types of undernutrition.
Adult Malnutrition Assessment: For adults, severity is commonly graded using Body Mass Index (BMI) and recent weight loss percentages.
Diverse Assessment Tools: Different historical systems like Gomez and Waterlow informed modern practices, which now incorporate tools like MUAC and z-scores for more precise grading.
Informs a Nutritional Diet: The specific grade of malnutrition dictates the urgency and type of nutritional diet and intervention required for effective recovery.

Malnutrition is a complex condition involving deficiencies, excesses, or imbalances in nutrient intake. It includes undernutrition (stunting, wasting, underweight), micronutrient deficiencies, and overnutrition (overweight and obesity). Grading malnutrition severity is essential for diagnosis, treatment, and public health. The grading approach varies based on age, type of malnutrition, and the classification system used.

Historical and Modern Classification Systems

Various systems have been used historically to categorize protein-energy malnutrition, particularly in children, using anthropometric measurements.

Gomez Classification

This early system classifies malnutrition based on weight-for-age percentage:

Grade I (Mild): 75–89% of expected weight for age.
Grade II (Moderate): 60–74% of expected weight for age.
Grade III (Severe): Less than 60% of expected weight for age.

Waterlow Classification

The Waterlow system differentiates acute and chronic malnutrition using weight-for-height and height-for-age.

Wellcome Classification

This system incorporates edema and weight-for-age to classify forms like kwashiorkor and marasmus.

WHO Z-Score System

The WHO's recommended system uses z-scores to compare a child's measurements to a reference population, allowing for precise grading and tracking over time.

The Standard Grades of Malnutrition in Children

For children under five, acute malnutrition is commonly graded as moderate or severe.

Moderate Acute Malnutrition (MAM)

MAM is indicated by a weight-for-height z-score (WHZ) between -2 and -3 or a mid-upper arm circumference (MUAC) between 115 mm and 125 mm.

Severe Acute Malnutrition (SAM)

SAM is a life-threatening condition defined by:

WHZ less than -3.
MUAC less than 115 mm.
Bilateral pitting edema.

Distinguishing Wasting and Stunting

Wasting (low weight-for-height) indicates acute weight loss. Stunting (low height-for-age) indicates chronic undernutrition. Both can occur together, increasing mortality risk.

Grading Malnutrition in Adults

Adult malnutrition is assessed using indicators like Body Mass Index (BMI) and weight loss.

Grading based on BMI:

Mild Malnutrition: BMI 17–18.5 kg/m².
Moderate Malnutrition: BMI 16–17 kg/m².
Severe Malnutrition: BMI less than 16 kg/m².

Grading based on Weight Loss:

Mild to Moderate Malnutrition: 5-10% weight loss in 6 months.
Severe Malnutrition: More than 10% weight loss in 6 months.

Comparison of Malnutrition Classification Systems


Feature	Gomez (Historical)	Waterlow (Historical)	WHO Z-Score (Modern Standard)
Primary Indicator	Weight-for-Age (%)	Weight-for-Height and Height-for-Age (%)	Weight-for-Height, Height-for-Age, and Weight-for-Age (z-scores)
Classification Type	Categorical (Mild, Moderate, Severe)	Distinguishes between Acute (Wasting) and Chronic (Stunting)	Continuous scale allowing for precise grading and tracking
Limitations	Cannot differentiate acute vs. chronic issues; relies on accurate age	Less sensitive than z-scores for identifying trends	Requires proper growth reference standards for accurate comparison
Key Strength	Simple to use with limited data (just age and weight)	Clear distinction between types of undernutrition	High precision, better for monitoring progress, standard for global comparison
Adult Grading	Not applicable	Not applicable	Often based on BMI and weight change

Assessment and Treatment Implications

Malnutrition grading guides the type and urgency of nutritional and medical intervention. SAM requires immediate therapeutic feeding, while MAM can be managed in outpatient settings. Adult treatment also depends on severity, ranging from dietary counseling to specialized support. Repeated assessments are crucial for tracking progress.

Conclusion: The Path from Grading to Recovery

Grading malnutrition severity is fundamental for effective nutritional care. It allows for quantifying the problem and tailoring interventions. While older systems like Gomez and Waterlow provided early frameworks, the WHO's z-score system is the most accurate standard, especially for children. This multi-faceted approach, combined with adult indicators, ensures appropriate nutritional diet and support for recovery.

World Health Organization information on malnutrition

Frequently Asked Questions

Wasting is a sign of acute malnutrition, indicating recent, significant weight loss. Stunting is a sign of chronic malnutrition, reflecting long-term inadequate nutrition that results in a child being too short for their age.

In adults, malnutrition is often graded based on a combination of BMI, unintentional weight loss percentages over a specific time frame, and clinical signs like loss of muscle mass.

A z-score is a statistical measure used by the WHO to compare a child's anthropometric measurements to a reference population. A negative z-score indicates a child's measurement is below the population median, with more negative scores indicating greater severity.

Bilateral pitting edema, or swelling in both feet, is a critical clinical sign used to diagnose Severe Acute Malnutrition (SAM), specifically kwashiorkor. Its presence indicates a severe form of malnutrition, regardless of a child's weight.

Yes, it is possible. This is often referred to as the 'double burden of malnutrition.' A person can have excess body weight (overnutrition) while simultaneously having a deficiency in essential micronutrients like vitamins and minerals.

MUAC is a measurement of the circumference of the upper arm, used as a screening tool, especially in children, to identify acute malnutrition. It's a quick and reliable indicator, with specific cut-offs used to diagnose Moderate and Severe Acute Malnutrition.

While the WHO z-score system is now the global standard for surveillance and program assessment, some older systems like Waterlow may still be used in certain clinical or research contexts to provide specific insights into the type of undernutrition (acute vs. chronic).