What is a Nutrition Diagnosis? Explaining the PES Statement

November 22, 2025 •

3 min read

According to the Academy of Nutrition and Dietetics, a nutrition diagnosis is the second step in a four-part process used by registered dietitians to provide high-quality care. This distinct process identifies, labels, and prioritizes a specific nutritional problem that a food and nutrition professional can treat or manage. Understanding what is a nutrition diagnosis is key to appreciating the role of the dietitian in the broader healthcare landscape.

Quick Summary

An RDN identifies and labels a patient's nutrition-related issue using the structured PES statement, which details the problem, its root cause, and the evidence. This process guides targeted nutrition intervention and monitoring, distinguishing it from a medical diagnosis.

Key Points

Core Definition: A nutrition diagnosis identifies a specific nutritional problem that a registered dietitian can treat or manage, distinguishing it from a medical diagnosis.
PES Statement: The diagnosis is documented in a three-part sentence called a PES statement, detailing the Problem, its Etiology (root cause), and the Signs/Symptoms (evidence).
Intake, Clinical, and Behavioral Domains: Nutrition diagnoses fall into three main categories: problems related to intake (e.g., energy or nutrients), clinical issues (e.g., swallowing difficulty), and behavioral/environmental factors (e.g., food access).
Targeted Intervention: The primary goal of identifying the etiology is to direct the nutrition intervention toward the most treatable root cause of the problem.
Systematic Process: A nutrition diagnosis is the second step in the four-step Nutrition Care Process (NCP), following assessment and preceding intervention and monitoring.
Objective and Subjective Evidence: Evidence supporting the diagnosis includes objective data from lab tests and physical exams (signs) and subjective information reported by the patient (symptoms).

The Core Components of a Nutrition Diagnosis: The PES Statement

A nutrition diagnosis is a specific, nutrition-related problem that a registered dietitian nutritionist (RDN) can address through nutrition interventions, distinct from a medical diagnosis which identifies a disease. The RDN documents this diagnosis using a standardized sentence called a PES statement, representing Problem, Etiology, and Signs/Symptoms.

The Problem: A Diagnostic Label

The Problem ('P') is a specific nutritional diagnostic label from a standardized list like the eNCPT. It describes a change in nutritional status that an RDN can manage, such as "inadequate energy intake" or "unintentional weight loss".

The Etiology: The Root Cause

The Etiology ('E') is the root cause or contributing factor of the nutrition problem, linked with "related to". Identifying the etiology is vital for tailoring interventions. Causes can be physiological, behavioral, or environmental. The RDN determines the most specific cause they can address.

The Signs and Symptoms: The Evidence

The Signs and Symptoms ('S') are the data supporting the diagnosis, connected by "as evidenced by" (AEB). Signs are objective, measurable data (e.g., lab results, weight changes), while symptoms are subjective, reported by the client (e.g., fatigue). This evidence confirms the presence and severity of the nutrition problem.

The Nutrition Care Process in Action

A nutrition diagnosis is the second step in the four-step Nutrition Care Process (NCP) used by RDNs. This process includes:

Nutrition Assessment: Gathering comprehensive client data.
Nutrition Diagnosis: Analyzing data to identify a problem and form a PES statement.
Nutrition Intervention: Developing and implementing a plan based on the diagnosis.
Nutrition Monitoring and Evaluation: Tracking progress and assessing the intervention's impact.

Comparison: Nutrition Diagnosis vs. Medical Diagnosis

This table outlines the key differences between nutrition and medical diagnoses.


Feature	Nutrition Diagnosis	Medical Diagnosis
Creator	Registered Dietitian Nutritionist (RDN)	Physician or other medical doctor
Focus	Identifies a specific nutrition-related issue treatable by a dietitian.	Identifies a disease, pathology, or medical condition.
Target of Intervention	Corrects or manages the nutritional problem.	Treats or manages the disease or medical condition.
Changeability	Can change or resolve as nutritional status improves.	May or may not be curable, often chronic.
Example	Excessive carbohydrate intake.	Diabetes Mellitus.

Practical Examples of PES Statements

Here are a few examples illustrating how PES statements are constructed:

Inadequate energy intake related to decreased appetite secondary to chemotherapy as evidenced by unintended weight loss of 10% in the past 6 months.
Excessive sodium intake related to excessive consumption of processed foods as evidenced by blood pressure readings of 185/115 and a 24-hour dietary recall indicating high sodium intake.
Inadequate weight gain related to limited adherence to nutrition recommendations for infant feeding as evidenced by gain of only 7 ounces over two months, with weight below the 2nd percentile for age.

Conclusion

A nutrition diagnosis, articulated through a PES statement, is a fundamental tool for RDNs. It allows them to clearly define nutrition problems, identify their causes, and provide evidence, guiding the creation of effective, personalized nutrition care plans. This process highlights the crucial and distinct role of nutrition professionals in healthcare.

Further resources can be found on the Academy of Nutrition and Dietetics website, which provides comprehensive information on the Nutrition Care Process and standardized terminology.

Frequently Asked Questions

A medical diagnosis identifies a disease or medical condition, like 'diabetes,' which is managed by a physician. In contrast, a nutrition diagnosis identifies a specific nutrition-related problem, like 'excessive carbohydrate intake,' which is addressed by a dietitian.

The 'PES' stands for Problem, Etiology, and Signs/Symptoms. It is the structured format used by dietitians to document a nutrition diagnosis clearly and concisely.

RDNs use a PES statement to articulate the nutrition problem, its cause, and the supporting evidence gathered during the nutrition assessment. This statement then informs the development of a targeted nutrition intervention.

Yes, a nutrition diagnosis is not static. It can and should change or even be resolved as a client's condition improves, dietary habits are modified, and nutrition interventions take effect.

Common categories, or domains, include Intake (problems related to nutrient or energy intake), Clinical (problems related to medical conditions), and Behavioral-Environmental (issues related to knowledge, attitudes, or environment).

The signs and symptoms include measurable, objective data like lab values, physical measurements (e.g., BMI), and physical findings. They also incorporate subjective information reported by the patient, such as fatigue or changes in appetite.

Identifying the root cause is critical because it directs the nutrition intervention toward the most effective point of action. By addressing the 'why,' dietitians can more successfully resolve or manage the nutrition problem.