How to Make a Nutrition Diagnosis: A Guide to the PES Statement

December 25, 2025 •

4 min read

The Nutrition Care Process (NCP) is a systematic approach providing a critical thinking framework for dietetics professionals. Learning how to make a nutrition diagnosis is the crucial second step in this process, which guides subsequent interventions and ensures patient-centered care.

Quick Summary

This guide details the process of creating a nutrition diagnosis using the PES statement format, which identifies the specific nutrition problem, its root cause, and supporting evidence.

Key Points

Systematic Process: The nutrition diagnosis is the second step in the four-stage Nutrition Care Process (NCP) used by RDNs for delivering high-quality care.
PES Statement: A nutrition diagnosis is communicated via a PES statement, a structured sentence detailing the Problem, its Etiology (cause), and supporting Signs and Symptoms (evidence).
Nutritional vs. Medical: Unlike a medical diagnosis, a nutrition diagnosis focuses on a problem that an RDN can resolve or improve through a specific nutrition intervention.
Data-Driven: Accurate PES statements rely on comprehensive data gathered during the nutrition assessment, including anthropometrics, biochemical tests, and client history.
Focus on Etiology: The intervention is directed at the etiology, or root cause, of the nutrition problem, not the symptoms.
Standardized Language: Using standardized terminology, such as that provided by the eNCPT, ensures clear and consistent communication among healthcare professionals.

Understanding the Nutrition Care Process (NCP)

Before you can effectively make a nutrition diagnosis, you must first understand its context within the larger Nutrition Care Process (NCP). The NCP is a four-step framework used by Registered Dietitian Nutritionists (RDNs) to provide high-quality nutrition care.

Nutrition Assessment: This initial step involves gathering and interpreting data to identify potential nutrition-related problems. Data is collected from various sources, including patient interviews, medical records, biochemical lab results, and anthropometric measurements.
Nutrition Diagnosis: The focus of this guide, this step involves using the assessment data to identify and label a specific nutrition problem that the RDN is responsible for treating.
Nutrition Intervention: Based on the diagnosis, a plan of action is developed and implemented to resolve or improve the identified problem.
Nutrition Monitoring and Evaluation: In the final step, the RDN checks if the intervention is working and whether the client is progressing toward their goals. This is an ongoing process that often leads back to reassessment.

The Core of Nutrition Diagnosis: The PES Statement

The standardized way to communicate a nutrition diagnosis is through a PES statement. This structured sentence clearly and concisely links the problem, its cause, and the evidence supporting it.

PES stands for:

Problem (The Nutrition Diagnosis Term): The specific nutrition issue identified from the assessment data. Terms are selected from a standardized list, such as those provided by the Academy of Nutrition and Dietetics.
Etiology (The Root Cause): This describes the underlying cause or contributing factor of the nutrition problem. It is linked to the 'Problem' by the phrase "related to".
Signs and Symptoms (The Evidence): This provides the objective and subjective data that proves the problem exists. It is connected to the 'Etiology' by the phrase "as evidenced by".

Step-by-Step: How to Make a Nutrition Diagnosis

Step 1: Gather and Analyze Assessment Data

Before formulating a diagnosis, you must have comprehensive data from your assessment. This data should cover key domains of nutritional status, including food/nutrition-related history, anthropometric measurements, biochemical data, nutrition-focused physical findings, and client history.

Step 2: Identify the Nutrition Problem

Use your assessment data to identify a specific nutrition-related problem. A nutrition diagnosis differs from a medical diagnosis; it's the nutritional issue resulting from a condition, not the condition itself. Nutrition diagnostic terminology falls into three domains: Intake, Clinical, and Behavioral-Environmental.

Step 3: Determine the Root Cause (Etiology)

Pinpoint the root cause, or etiology, of the identified nutrition problem. A good etiology is something a nutrition intervention can target. Examples include pain while eating leading to unintended weight loss or regular fast-food consumption leading to high sodium intake.

Step 4: List the Evidence (Signs and Symptoms)

Support your problem and etiology with evidence from your assessment. This includes objective signs and subjective symptoms. Examples include weight loss and low serum albumin for malnutrition, or elevated blood pressure and fluid retention for excessive sodium intake.

Comparison: Nutrition Diagnosis vs. Medical Diagnosis

Distinguishing between a nutrition and a medical diagnosis is crucial. A nutrition diagnosis addresses issues a dietitian can treat, while a medical diagnosis addresses broader disease states.


Feature	Nutrition Diagnosis	Medical Diagnosis
Focus	Identifies a specific nutrition problem that can be resolved or improved through nutrition intervention.	Identifies a disease or pathological condition.
Example	Inadequate protein intake.	Chronic Kidney Disease.
Who Diagnoses	Registered Dietitian Nutritionist (RDN).	Physician.
Can it Change?	Yes, it can change or resolve as the patient's nutritional status improves.	Typically permanent, though the condition can be managed.
Intervention Target	The etiology or root cause of the nutritional problem.	The underlying disease state itself.

Putting It All Together: PES Statement Examples

Here are some examples of correctly written PES statements based on different scenarios:

Malnutrition: "Inadequate energy intake related to pain while eating, as evidenced by estimated intake less than 50% of calculated needs and a 20 lb weight loss over the last 3 months".
Obesity: "Excessive oral food and beverage intake related to large portion sizes, as evidenced by BMI of 40 kg/m^2 and estimated energy intake above estimated needs".
Iron Deficiency: "Inadequate iron intake related to a vegan diet and food preferences, as evidenced by fatigue, low serum ferritin levels, and food records showing limited consumption of iron-rich foods".
Knowledge Deficit: "Food and nutrition-related knowledge deficit related to new diagnosis of celiac disease, as evidenced by verbalized confusion about which foods contain gluten".

Conclusion: The Importance of an Accurate Nutrition Diagnosis

An accurate nutrition diagnosis is fundamental to effective nutrition care. It converts assessment data into a focused problem statement, guiding interventions and monitoring. Using the PES format ensures clear communication and supports targeted, evidence-based care to improve client outcomes. Mastering PES statement writing is essential for RDNs providing patient-centered care. For further resources, the eNCPT from the Academy of Nutrition and Dietetics is a valuable tool.

Frequently Asked Questions

A PES statement is a structured sentence used by dietitians to document a nutrition diagnosis. It stands for Problem, Etiology, and Signs/Symptoms, linking the nutritional issue, its cause, and the supporting evidence.

A nutrition diagnosis addresses a specific nutrition-related problem that a dietitian can resolve through intervention (e.g., inadequate calorie intake). A medical diagnosis, made by a physician, identifies a disease or medical condition (e.g., cancer).

The three domains are Intake (problems related to nutrient, energy, or fluid intake), Clinical (problems related to medical or physical conditions), and Behavioral-Environmental (problems related to knowledge, beliefs, or environment).

A dietitian collects information from a nutrition assessment, which includes food history, anthropometric measurements, biochemical data, nutrition-focused physical findings, and client history.

Identify the problem that is the most urgent and can be resolved or improved by a nutrition intervention. Focus on the root cause that the dietitian can directly address.

The etiology identifies the root cause or contributing factors of the nutrition problem. The nutrition intervention should be specifically targeted at resolving or improving this root cause.

The next steps in the Nutrition Care Process are the Nutrition Intervention, where a plan of action is implemented, and Nutrition Monitoring and Evaluation, where progress is assessed to see if the goals are being met.