A PES statement is a structured sentence that communicates a nutrition diagnosis in three parts: the Problem, the Etiology (cause), and the Signs and Symptoms (evidence). It follows a fixed format: “[Problem] related to [Etiology] as evidenced by [Signs and Symptoms].” Every registered dietitian uses this format as part of the Nutrition Care Process, and learning to write one well is one of the most practical skills in dietetics education. Here’s how each piece works and how to put them together.
The Three Parts of a PES Statement
The acronym PES stands for Problem, Etiology, and Signs/Symptoms. Two linking phrases hold the sentence together: “related to” connects the problem to its cause, and “as evidenced by” connects the cause to measurable proof. A complete PES statement always reads as a single sentence following that template.
Problem: This is the nutrition diagnosis itself, chosen from the standardized Nutrition Care Process Terminology. Nutrition diagnoses fall into three broad domains: Intake (too much or too little of a nutrient or food), Clinical (conditions affecting nutrition status like swallowing difficulty or altered lab values), and Behavioral-Environmental (knowledge gaps, access issues, or disordered eating patterns). The problem you select should be something a dietitian can address, not a medical diagnosis. “Type 2 diabetes” is a medical diagnosis. “Excessive carbohydrate intake” is a nutrition diagnosis.
Etiology: This is the root cause, the “why” behind the problem. It answers the question: what is driving this nutrition issue? The etiology is critical because it directly determines what your intervention will target. If the etiology is large portion sizes, your intervention might focus on portion education. If the etiology is poor appetite from medication side effects, your intervention looks completely different.
Signs and Symptoms: This is the objective and subjective evidence proving the problem exists. Lab values, weight changes, dietary intake data, growth chart percentiles, and patient-reported information all qualify. The key requirement is that these indicators are specific and measurable enough that you can re-evaluate them later to determine whether the problem has improved.
How to Choose the Right Problem
Start with your nutrition assessment data and ask: what nutrition problem does this data point to? Resist the urge to pick a medical condition. Your job is to identify the nutritional layer of the patient’s situation. A patient recovering from a traumatic brain injury may have swallowing difficulty as a clinical nutrition diagnosis, even though the brain injury is the underlying medical issue.
Be as specific as the terminology allows. “Inadequate oral food and beverage intake” is more useful than a vague label like “poor nutrition.” The more precise the problem, the easier it is to build the rest of the statement and plan an intervention that actually targets it.
Selecting an Etiology You Can Act On
The etiology is where many PES statements go wrong. A good test: can you envision a nutrition intervention that would address this root cause and, in doing so, resolve or improve the problem? If you can’t, the etiology is probably outside your scope or too broad to be useful.
Choose the most specific root cause available. If a patient has inadequate intake, the etiology could be “poor appetite,” but it could also be something more actionable like “nausea from chemotherapy” or “limited access to food during work hours.” The more specific you get, the clearer your intervention path becomes. That said, the etiology still needs to be something you can realistically influence. Listing a cause you have no ability to change (like a genetic condition) leaves you with nowhere to go in your care plan.
Making Signs and Symptoms Measurable
Vague evidence weakens the entire statement. “Low weight” is not as useful as “weight-for-length at the 3rd percentile.” “Eats too much” is not as useful as “estimated energy intake exceeds estimated needs by 500 calories per day.” The signs and symptoms need to be specific enough that when you see the patient again, you can measure the same indicators and determine whether anything has changed.
Common types of measurable evidence include BMI or growth percentiles, documented weight change over a defined time period (such as a 10-pound loss in 30 days), estimated nutrient intake compared to needs, lab results, and patient or caregiver reports of specific behaviors. Use numbers wherever possible. Include timeframes. The goal is to leave no ambiguity about what “improved” would look like at the next visit.
Complete PES Statement Examples
Seeing the format in action makes it easier to replicate. Here are several examples across different situations:
- Excessive intake: “Excessive energy intake related to consumption of fast food meals once per day as evidenced by BMI-for-age at the 97th percentile.”
- Inadequate intake: “Inadequate oral food and beverage intake related to dysphagia as evidenced by weight loss of 10 pounds in 30 days and estimated energy intake below 50% of estimated needs.”
- Inadequate intake (pediatric): “Inadequate energy intake related to poor appetite as evidenced by weight loss of 1 pound in the past month.”
- Breastfeeding: “Breastfeeding difficulty related to infant accustomed to bottle-feeding as evidenced by inability to latch baby to breast.”
Notice how each example names a specific nutrition problem (not a medical diagnosis), identifies a cause the practitioner could potentially address through education or intervention, and includes concrete, observable evidence.
How to Check Your Work
After drafting a PES statement, run it through a series of validation questions. These come from evaluation frameworks developed for the Nutrition Care Process and will catch most common errors before they become habits.
First, ask whether you can resolve or improve the nutrition diagnosis. If the problem is entirely outside your scope, you’ve likely written a medical diagnosis instead of a nutrition diagnosis. Next, confirm that the etiology is the most specific root cause available. A vague cause leads to a vague intervention. Then check whether you can envision a concrete intervention that targets the etiology. If the etiology doesn’t suggest a clear next step, it needs to be revised.
On the evidence side, ask whether monitoring the signs and symptoms over time will tell you if the problem is getting better. If your evidence is too vague to re-measure, tighten it up with numbers, percentiles, or timeframes. Finally, verify that your assessment data actually supports all three components. The problem, the cause, and the evidence should all align logically. If any piece feels disconnected, something in the chain needs adjusting.
Mistakes That Weaken a PES Statement
The most common error is using a medical diagnosis as the problem. “Diabetes related to insulin resistance as evidenced by elevated blood glucose” is a medical statement, not a nutrition diagnosis. The nutrition layer might be “excessive carbohydrate intake” or “inconsistent meal timing,” with the medical condition serving as context in the etiology instead.
Another frequent issue is choosing an etiology you cannot influence. If the root cause is something like a traumatic brain injury, you can’t treat that, but you can treat the swallowing difficulty or the inadequate intake that results from it. Push the etiology toward the part of the chain where nutrition care makes a difference.
Writing vague signs and symptoms is the third pitfall. “Slowed growth” is harder to track than “weight-for-length at the 3rd percentile.” “Patient reports eating less” is weaker than “estimated energy intake below 50% of estimated needs.” Every piece of evidence should pass a simple test: could another practitioner measure the same thing at the next appointment and compare?
Connecting the PES Statement to Your Care Plan
The PES statement is not just documentation. It is the foundation for everything that follows in the Nutrition Care Process. Your intervention targets the etiology. Your monitoring plan tracks the signs and symptoms. If the etiology is “consumption of fast food meals once per day,” the intervention might include meal planning education or strategies for preparing quick meals at home. At the follow-up visit, you would reassess the same indicators listed in your signs and symptoms, such as BMI percentile or estimated energy intake, to see whether the problem has improved.
This is why precision matters at every level of the statement. A loosely written PES statement produces a loosely directed care plan. A specific one gives you a clear target for intervention and a built-in way to measure whether your work is making a difference.