Loss of Appetite in Clinical Practice: How to Approach, Examine, and Act in the First Encounter

“I just haven’t felt like eating lately.”
This simple statement—so common in OSCE scenarios and outpatient visits—can be the tip of a serious underlying condition.
From eating disorders to endocrine abnormalities, loss of appetite should not be dismissed as a minor complaint.
In this article, we will walk you through a structured, case-based approach to history-taking, differential diagnosis, and initial management of appetite loss.

• 🔍 A structured approach to differential diagnosis of appetite loss using the VITAMIN CDE framework — including anorexia nervosa, depression, and endocrine disorders
• 🩺 Practical history-taking and physical examination skills for loss of appetite, essential for OSCE and clinical practice — featuring SCOFF screening and red flags
• 🏥 How to manage initial outpatient care and determine when to refer — including criteria for psychiatric referral and multidisciplinary coordination

🚪 Doorway Information

• Age/Sex: 20-year-old female
• Chief Complaint: Loss of appetite
• Vital Signs: T 36.1°C, HR 52 bpm, BP 92/60 mmHg, SpO₂ 98% (room air)

“I haven’t felt like eating for a while now… I feel nauseous when I eat, and I really don’t want to gain weight.
My family insisted that I come, so I had no choice.”

When you hear a patient say, “I just don’t feel like eating,” how do you respond?
It’s a common complaint in both OSCE scenarios and real-world clinical settings—but also one that often leaves trainees unsure where to begin.

• “There are too many possible causes—where do I even start?”
• “Is this a physical condition, or something psychological?”
• “Is she really sick—or is this just a phase or a personal issue?”

In truth, appetite loss is one of those everyday symptoms seen across all age groups—from teenagers to the elderly—and in nearly every specialty: internal medicine, psychiatry, family practice, and more.

It demands clinical balance: you must not ignore it, but overreacting can also do harm.
In this case, the patient says, “I don’t want to gain weight” and “My family forced me to come.” These are strong clues that point toward an eating disorder.

However, don’t overlook other possibilities—loss of appetite can also be an early sign of endocrine disorders, chronic infections, or even malignancy.

This brings us to two key clinical questions:

1. Is this a signal from the body or a ?
2. How far should you go in outpatient care, and when is it time to refer?

In the following sections, we will walk through this case step by step—starting with how to turn a vague symptom like “I don’t feel like eating” into specific clinical hypotheses.

🔎 Fact (What We Know)

• 20-year-old woman presenting with loss of appetite
• Feels nauseous when eating
• Says, “I don’t want to gain weight”
• Attended the visit because “my family made me come”
• Vital signs: HR 52 bpm, BP 92/60 mmHg – both on the low side

🧩 Problem (Reframing the Complaint)

• Persistent appetite loss with functional impact
• Distorted body image and fear of weight gain
• Lack of insight and poor internal motivation to seek care

This is clearly more than just a “stomach bug” or poor diet.
Her symptoms suggest an underlying psychiatric or endocrine condition.

💡 Hypothesis (Differential Diagnosis via VITAMIN CDE)

• Vascular: Rare – mesenteric ischemia (unlikely in this age)
• Infection: H. pylori, chronic gastritis, tuberculosis
• Trauma: Psychological trauma, history of abuse
• Autoimmune: SLE, Hashimoto’s thyroiditis
• Metabolic/Endocrine: Hypothyroidism, Addison’s disease, diabetes
• Iatrogenic: Medication side effects – SSRIs, chemotherapy, herbal remedies
• Neoplastic: GI or brain tumors
• Congenital: Genetic predisposition to eating disorders
• Degenerative: Dementia-related appetite loss (unlikely here)
• Endocrine/Psychiatric: Anorexia nervosa, depression, personality disorders

🎯 Top 3 Likely Diagnoses

1. Anorexia nervosa — fear of gaining weight, poor insight, bradycardia
2. Major depressive disorder — loss of appetite is a core symptom
3. Hypothyroidism — bradycardia and fatigue may overlap

These hypotheses will guide the focused history-taking in the next step.

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📌 Mini-CQ: Is “anorexia” the same as “anorexia nervosa”?

No. “Anorexia” simply means appetite loss (a symptom), while “anorexia nervosa” is a formal psychiatric diagnosis.
Always include “nervosa” when referring to the disorder to avoid confusion.

🔍 Using OPQRST to Characterize the Symptom

• O – Onset: When did the loss of appetite begin? Was it sudden or gradual?
• P – Provocation/Palliation: Any triggers? Does anything make it better or worse?
• Q – Quality: What does “not feeling like eating” mean? Nausea? Changes in taste? No hunger?
• R – Region/Radiation: Any discomfort in the stomach? Any related chest or GI symptoms?
• S – Severity: To what extent are they eating? How many meals per day? Any significant changes?
• T – Timing: Any patterns in the day? Worse in the morning or evening?

Special attention should be given to Quality and Severity — explore how the patient interprets their symptom.

Associated symotoms to ask for: 

🧠 Psychiatric & Behavioral Disorders

• Anorexia nervosa: Fear of gaining weight, body image distortion, amenorrhea, bradycardia, lanugo, poor insight
• Bulimia nervosa: Binge eating, purging behaviors (vomiting, laxatives), dental erosion, parotid swelling, electrolyte abnormalities
• Major depressive disorder: Anhedonia, fatigue, insomnia or hypersomnia, weight loss, slowed speech or movement

🩺 Endocrine & Metabolic Disorders

• Hypothyroidism: Fatigue, cold intolerance, constipation, dry skin, bradycardia, weight gain or poor appetite
• Addison’s disease: Fatigue, nausea, hyperpigmentation, hypotension, salt craving, hyponatremia
• Diabetes (esp. type 1 onset or DKA): Polyuria, polydipsia, weight loss, fatigue, fruity breath
• Hypercalcemia: Constipation, nausea, abdominal pain, “bones, stones, groans, and psychiatric overtones”

🦠 Infectious & Neoplastic Causes

• Tuberculosis: Night sweats, low-grade fever, weight loss, chronic cough, hemoptysis
• H. pylori / chronic gastritis: Bloating, early satiety, epigastric discomfort
• GI or CNS tumors: Early satiety, nausea, vomiting, focal neurological symptoms (if CNS), anemia

⚠️ Red Flag Symptoms to Watch For

• Rapid weight loss >5% body weight in 1 month
• Bradycardia (HR <40 bpm), hypotension, hypothermia
• Electrolyte disturbances (K⁺, Na⁺, Mg²⁺)
• Syncope, altered mental status, self-harm ideation

🧾 PAM HITS FOSS – A Framework for Medical History

• Past medical history: Depression, eating disorders, hypothyroidism, diabetes
• Allergy: Food or medication allergies
• Medications: SSRIs, chemotherapy, herbal medicines (e.g., Boifuso Toseisan)
• Hospitalization / Injury / Trauma: Past admissions, accidents, emotional trauma
• Surgery: GI or endocrine surgeries
• Family history: Eating disorders, psychiatric illnesses
• OBGYN: Amenorrhea, irregular menstruation, birth control use
• Sexual history: Trauma or abuse that may affect eating behavior
• Social history: Smoking, alcohol, drugs, stress, sleep, exercise, and diet patterns

❓ Mini-Clinical Questions (Q2 & Q3)

• Q2: “If she says she’s fat even though underweight, is she serious?” → Yes. This is a core feature of body image distortion. Validate her feelings while assessing insight.
• Q3: “When she says she’s dieting, is it always pathological?” → Not necessarily. But clarify the reasons, methods, and restrictions. Look for irrational or excessive behaviors.

🗣️ Interviewing Tips – Empathetic Inquiry

• “Have you noticed any recent weight changes?”
• “Can you describe what ‘not wanting to eat’ feels like?”
• “Has anyone—like your family or friends—commented on your eating?”
• “Do you ever feel scared or guilty about eating?”

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Once you’ve gathered this information, it’s time to move on to the physical exam.
Remember, even when patients “look fine,” their vital signs and body signals may tell a different story.

👀 General Appearance and Systematic Observation

• Facial expression / Body habitus: Emaciation, sunken eyes, diminished facial expressivity
• Vital signs: Hypothermia, bradycardia (HR <40 bpm), hypotension, orthostatic changes
• Skin & nails: Dry skin, lanugo (fine hair), brittle nails, cold extremities
• Oral cavity: Dry mucosa, dental erosion, pharyngeal scratches (suggesting self-induced vomiting)
• Abdomen: Often soft and non-tender; may show bloating or constipation signs
• Neurological status: Delayed response, poor concentration, signs of hypoglycemia or hyponatremia

🚩 Red Flag Signs

• HR <40 bpm or bradycardia + hypotension (SBP <90 mmHg or orthostatic drop >20 mmHg)
• Hypothermia (T <35.5°C)
• Altered consciousness, poor concentration, delayed response
• Signs of severe electrolyte disturbance or hypoglycemia
• Positive SUSS test (unable to maintain sitting or standing position due to circulatory collapse)

🛠️ Tools & Measurements to Support Clinical Judgement

• Body weight & BMI: Mandatory at first visit. Compare against ideal weight and growth curves if available
• Orthostatic vitals: Monitor HR/BP in supine vs. standing (part of SUSS test)
• Body temperature: Hypothermia may signal advanced malnutrition or endocrine dysfunction
• Oropharyngeal and fundoscopic exam: Look for indirect signs of vomiting or nutritional deficiency

🗣️ Clinical Thinking During the Exam

• “Her pulse is unusually slow… need to rule out hypothyroidism or consider severe malnutrition.”
• “The gap between her appearance and reported weight is striking—nutritional status seems poor.”
• “Her reactions are sluggish… Could hyponatremia or hypoglycemia be playing a role?”

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With these observations, we now proceed to investigations to confirm or refute our working hypotheses.
Let’s move on to Step 3: selecting the right tests with a purpose.

🧪 Key Lab Tests to Start With

• Complete Blood Count (CBC), CRP: Assess for anemia, infection, chronic inflammation
• Electrolytes, Renal Function: Sodium, potassium, calcium, magnesium – often altered by vomiting, poor intake, or diuretics
• Blood Glucose: Rule out hypoglycemia, especially in malnourished or diabetic patients
• Thyroid Function (TSH, FT4): Hypothyroidism may explain bradycardia and fatigue
• Liver & Pancreatic Enzymes: Assess nutritional status and screen for drug-related toxicity
• Endocrine Panel: Cortisol, ACTH (to assess for adrenal insufficiency)
• Urine β-hCG: Always rule out pregnancy in reproductive-age females

🖼️ Imaging – Targeted, Not Routine

• Abdominal Ultrasound: Useful to evaluate GI organs, uterus/ovaries, constipation, or gallbladder issues
• Brain MRI/CT: If neurological signs or significant psychiatric symptoms suggest CNS involvement
• Chest X-ray: For TB, chronic infection, or suspicion of malignancy

Imaging is not routine unless indicated by physical signs or lab results.
“Just to be safe” is not a good enough reason—over-testing may increase anxiety and yield low-value results.

📊 Interpreting Results Clinically

• Normal CRP, WBC: Low likelihood of infection/inflammation
• Elevated TSH: Supports hypothyroidism hypothesis
• Electrolyte imbalances (↓Na, ↓K): Suggest vomiting, laxative/diuretic use, or severe undernutrition
• Low Hb: May reflect nutritional anemia or menstrual irregularities

If infection, malignancy, and endocrine disorders are ruled out, consider primary psychiatric disorders such as anorexia nervosa or depression.

🗣️ Clinical Thinking During Testing

• “CRP is normal… infection seems unlikely.”
• “TSH is mildly elevated… need to evaluate for hypothyroid symptoms more closely.”
• “Low potassium — could this be from purging? I should ask again about vomiting or laxative use.”

🚫 What Not to Order

• CT/MRI in healthy-appearing young patients without focal symptoms
• Tumor markers or autoimmune panels without strong clinical suspicion

💡 Diagnostic Tips

• Design your workup to rule out life-threatening or treatable causes first
• Don’t forget pregnancy and endocrine screening—even in “non-obvious” cases
• Normal results are still useful: they help shift the focus to psychiatric causes

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Now that we’ve completed history, exam, and testing, let’s revisit our case and apply what we’ve learned step by step.

🟢 Step 1: History Taking – Fact → Problem → Hypothesis

Doctor: “What brings you in today?”

Patient: “I haven’t felt like eating lately… I feel sick when I eat, but I really don’t want to gain weight. My family insisted I come.”

Doctor: “How much weight have you lost? What foods cause nausea?”

Patient: “About 6 kilograms in the past 3 months. I can eat porridge sometimes… but I just don’t want to eat anything.”

Her comment about not wanting to gain weight, coupled with low motivation to seek help, suggests impaired insight.
Her SCOFF responses were positive. We prioritized eating disorders, while keeping depression and endocrine causes in mind.

• Fact: Appetite loss, nausea, fear of gaining weight, came because of family pressure
• Problem: Progressive appetite loss, body image distortion, poor insight
• Hypothesis: (1) Anorexia nervosa (2) Depression (3) Hypothyroidism

🔍 Step 2: Physical Examination – Focused Check for Red Flags

On inspection, she appeared underweight, with a blank facial expression and cold extremities.
Vital signs showed bradycardia (HR 52 bpm) and borderline hypotension (BP 92/60 mmHg).
The SUSS test revealed postural instability, raising concerns for circulatory compromise due to malnutrition.

No clear signs of purging (no oral injury, no hand scars), suggesting a restrictive eating pattern.
Hypothyroidism and adrenal insufficiency were still considered based on her vitals and overall appearance.

🧪 Step 3: Investigations – Narrowing the Differential

• CBC: Mild anemia (Hb 10.8 g/dL)
• Electrolytes: Mild hyponatremia and hypokalemia
• TSH: Low-normal
• CRP: Negative
• Abdominal ultrasound: Ovaries and uterus showed signs of atrophy, no follicles observed

No clear evidence of infection, malignancy, or endocrine disorders.
The imaging suggested hypothalamic amenorrhea secondary to nutritional deficiency.

✅ Conclusion:

At this stage, the most likely diagnosis is anorexia nervosa.
We planned continued outpatient follow-up while preparing for psychiatric referral and family-based support.

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Let’s now explore how to determine the right timing and method for treatment and referral in cases like this.

🎯 Goal of Initial Management

• Short-term: Ensure physical safety — prevent bradycardia, electrolyte crisis, or impaired consciousness
• Mid-term: Stabilize weight, restore menstruation, support daily functioning
• Long-term: Prevent relapse, support psychological recovery and social reintegration

In the early stage, the focus is not to “make the patient eat,” but to protect their life.
This must be clearly communicated to the patient and their family.

🧠 Initial Interventions – What Primary Care Can Do

• Psychological approaches: CBT-E (enhanced cognitive behavioral therapy), motivational interviewing, family-based therapy
• Medication: SSRIs (e.g., fluoxetine) for comorbid depression or obsessive traits
• Nutritional guidance: Gradual diet adjustments through a multidisciplinary team

🚨 Urgent Referral or Hospitalization If Any of the Following:

• Heart rate <40 bpm or systolic BP <90 mmHg
• Core temperature <35.5°C
• Positive SUSS test (unable to sit or stand without support)
• Electrolyte abnormalities (Na⁺ <130, K⁺ <3.0 mmol/L)
• Altered mental state, suicidal ideation, or dangerous behaviors

🤝 What Primary Care Providers Can Offer

• Establish trust even when the patient lacks insight
• Frame the diagnosis as part of a “support system,” not as a label
• Coordinate with family, school, or workplace where appropriate

💡 Practical Tips

• Avoid focusing on the label — instead, explain the need for “a support plan for recovery”
• Prepare clear handover notes for referrals: timeline, vitals, weight/BMI, eating behaviors, test results
• Use simple, jargon-free summaries for family and school staff

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Once the referral is made, the role of the generalist continues — regular check-ins, monitoring, and bridging trust between specialties and support networks.

🗣️ Interviewing Tips – Especially for Young Female Patients

• Don’t start with “Do you have an eating disorder?” — Instead, explore appetite, weight changes, and emotions gently.
• Use neutral, non-judgmental questions like:
  “How do you feel about eating lately?” or “What does your typical meal look like these days?”
• When body image distortion is suspected, try reflective questions: “Do you feel your current weight reflects your ideal?”
• Validate feelings without endorsing unhealthy behaviors: “It sounds like you’ve been under a lot of pressure.”

🩺 Physical Exam Tips

• Look beyond weight — signs like cold extremities, dry skin, and bradycardia can be subtle but life-threatening.
• Always check orthostatic vitals and core temperature in suspected malnutrition.
• Don’t miss clues like amenorrhea, brittle nails, lanugo, or slowed reflexes.

💬 Language Tips for Empowering Patients

• “You’re not alone. Many people experience this and recover with support.”
• “It’s not about blame — it’s about making sure your body and mind are safe.”
• “I’m here to help you find the right team — you don’t have to do this alone.”

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💎 Clinical Pearl

“Patients must be heard not only through their words, but through the silences between them.”
— Unknown

This is especially true for eating disorders, where silence, denial, or minimization may speak louder than any complaint.
Reading between the lines — and listening with compassion — is the first step in care.

🗣️ OET Speaking Session – Loss of Appetite in a Young Woman

👥 Scenario

You are a general practitioner seeing a 20-year-old woman who presents with persistent loss of appetite, mild nausea, and weight loss. She mentions she doesn’t want to gain weight and says she came only because her family insisted.

You are concerned about anorexia nervosa, but also need to rule out endocrine or infectious causes.

🎯 Your Task

• Explore the symptom and its emotional/behavioral context
• Gently assess body image and possible disordered eating
• Explain your concerns and propose referral to appropriate support
• Address resistance, denial, or low insight empathetically

💬 Common Patient Cues & Sample Doctor Responses

🧠 Challenging Questions & Sample Doctor Responses

✉️ OET Writing Task – Sample Referral Letter

Today’s Date

Dr. Fiona White
Adolescent Mental Health Team
Lakeside Medical Centre

Re: Ms. Emma R., 20 years old

Dear Dr. White,

I am writing to refer Ms. Emma R., a 20-year-old university student, for further evaluation and multidisciplinary management of suspected anorexia nervosa.

Emma presented with a three-month history of appetite loss, progressive weight loss (~6 kg), and expressed fear of weight gain. She reports nausea when eating and denies bingeing or purging. She has little insight into her condition and says she came only due to family pressure.

On examination, she appeared underweight with bradycardia (HR 52 bpm) and low-normal blood pressure (92/60 mmHg). The SUSS test showed postural instability. Blood tests revealed mild hyponatremia and hypokalemia. TSH and cortisol were within normal limits. An abdominal ultrasound showed signs of hypothalamic amenorrhea.

I would appreciate your assessment regarding diagnosis confirmation, treatment planning, and support with nutritional and psychological rehabilitation. Please feel free to contact me if further information is needed.

Yours sincerely,

Dr. [Your Name]
General Practitioner

🔗 Related Articles & Japanese Version Link

• 🇯🇵 ▶ Read in Japanese: 「最近、食べる気がしないんです」—その一言から読み解く診療の力
• 🧠 How to Approach Depression – Fatigue, Low Mood, or Something More?
• 💧 Hypovolemia vs. Dehydration – Clinical Signs and Diagnostic Pitfalls
• 🩺 Unintentional Weight Loss – Is It Just a Diet, or a Red Flag?
• 🤢 Nausea & Vomiting – Gastrointestinal, Neurologic, and Metabolic Causes

📚 References

• American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5). American Psychiatric Publishing; 2013.
• National Institute for Health and Care Excellence (NICE). Eating disorders: recognition and treatment. NG69. 2017.
• 日本摂食障害学会. 摂食障害治療ガイドライン2020年版. 医学書院, 2020年.
• Mehler PS, Brown C. Anorexia nervosa – medical complications. J Eat Disord. 2015;3:11.
• Morgan JF, Reid F, Lacey JH. The SCOFF questionnaire: assessment of a new screening tool for eating disorders. BMJ. 1999;319(7223):1467–8.