What is the approach to work up a patient for weight loss?

Workup for Weight Loss in Adults

Critical First Distinction: Intentional vs. Unintentional Weight Loss

The workup for weight loss depends entirely on whether the weight loss is intentional (patient seeking obesity treatment) or unintentional (unexplained weight loss requiring diagnostic evaluation).

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For UNINTENTIONAL Weight Loss: Diagnostic Workup

Immediate Assessment

• Urgent neuroimaging with MRI brain with contrast is mandatory if headaches are present to exclude intracranial pathology 1
• Urgent ophthalmologic examination to assess for papilledema indicating increased intracranial pressure 1
• Calculate percentage of weight loss: >5% in 3 months or >8% in any timeframe is significant and requires full evaluation 1

Initial Laboratory Testing

• HbA1c for diabetes screening 1
• Thyroid function tests (TSH) to evaluate for hyperthyroidism or hypothyroidism 1
• Complete metabolic panel, CBC
• Physical examination including thyroid palpation, assessment for tremor, tachycardia, or bradycardia 1

Symptom-Directed Evaluation

• Elicit pain location and characteristics, pulmonary complaints, gastrointestinal symptoms (dysphagia, abdominal pain, changes in bowel habits, bleeding) 1
• Assess for constitutional symptoms including fever and night sweats 1
• Screen for psychiatric disorders (depression, anxiety, eating disorders) as these account for 16% of cases when organic causes are excluded 1
• Comprehensive medication review as antidepressants and antihyperglycemics can cause weight changes 1

Prognosis and Follow-up

• Malignancy is found in 22-38% of patients with significant unintentional weight loss 1
• Watchful waiting is only appropriate if baseline evaluation is completely normal, patient remains clinically stable, and close monitoring can be ensured 1

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For INTENTIONAL Weight Loss: Obesity Management Workup

Initial Assessment and Risk Stratification

• Calculate BMI and measure waist circumference to quantify obesity severity 1, 2
• Screen for obesity-related comorbidities: type 2 diabetes, hypertension, dyslipidemia, sleep apnea, nonalcoholic fatty liver disease 2
• Screen for depression, anxiety, and binge eating disorder before initiating treatment as these derail weight loss efforts 2
• Assess patient motivation and readiness to change, including stressors 3, 4
• Review medications that may cause weight gain (antidepressants, antihyperglycemics) 2

Treatment Algorithm Based on BMI

BMI 25-26.9 kg/m² with comorbidities:

• Lifestyle intervention: diet, physical activity, behavior therapy 3

BMI 27-29.9 kg/m²:

• Lifestyle intervention for all patients 3
• Add pharmacotherapy if comorbidities present 3
• Consider endoscopy-based interventions 3

BMI 30-34.9 kg/m²:

• Lifestyle intervention as foundation 3
• Add pharmacotherapy if lifestyle changes fail after 3 months 2
• Endoscopy-based interventions available 3
• Consider bariatric surgery if comorbidities present 3

BMI 35-39.9 kg/m²:

• Comprehensive lifestyle intervention 3
• Pharmacotherapy indicated 3
• Bariatric surgery strongly considered 3

BMI ≥40 kg/m²:

• All treatment modalities available 3
• Bariatric surgery is definitive option 3

Specific Treatment Components

Dietary Intervention:

• Create caloric deficit of 500-1,000 kcal/day to achieve 1-2 lb/week weight loss 3, 2
• Reduce both dietary fat and carbohydrates to facilitate calorie reduction 3
• Ensure adequate protein, vitamins, and minerals 2

Physical Activity Requirements:

• Minimum 150 minutes/week of moderate-intensity aerobic exercise 2, 5
• Add resistance training 2-3 times/week involving all major muscle groups 2
• For weight loss maintenance: 225-420 minutes/week of moderate-intensity exercise 5
• Multiple short bouts (10 minutes, 3-4 times daily) improve adherence compared to single long sessions 3

Behavioral Modification Strategies:

• Self-monitoring of food intake, body weight, physical activity, and cravings 2, 3
• Goal setting with specific short-term targets 3
• Stimulus control to identify and break links with eating triggers 3
• Cognitive restructuring to change perceptions undermining weight control 3
• Problem solving and relapse prevention planning 3
• Stress management to prevent dysfunctional eating 3

Pharmacotherapy Indications:

• Initiate when BMI ≥30 kg/m² regardless of comorbidities, or BMI ≥27 kg/m² with at least one obesity-related complication 2
• First-line: GLP-1 receptor agonist-based medications achieving 15-25% weight reduction and reducing cardiovascular events 2
• Orlistat 120 mg three times daily with meals as FDA-approved option for adults ≥18 years 6
• Discontinue if <5% weight loss at 12 weeks 4
• Must be combined with comprehensive lifestyle program, never used alone 3

Bariatric Surgery:

• Consider for BMI ≥40 kg/m² or BMI ≥35 kg/m² with comorbidities when less invasive methods have failed 3, 2
• Achieves approximately 25-30% weight loss 2

Treatment Goals and Monitoring

• Target initial weight loss of 5-10% from baseline, which provides substantial health benefits including reduced cardiovascular events and prevention of type 2 diabetes 2, 3
• Evaluate at 3 months: if minimal weight loss occurs, escalate to pharmacotherapy or surgical referral 2
• Monthly follow-up initially, then every 3 months 4
• Implement weight maintenance program for at least 1 year with monthly counseling to prevent regain 3

Common Pitfalls to Avoid

• Never use pharmacotherapy without accompanying lifestyle modification 3
• Do not focus solely on weight loss percentage; assess improvements in comorbidities, quality of life, and psychological well-being 7
• Avoid restrictive dieting in children/adolescents as this causes weight gain and binge eating 8
• Recognize obesity as a chronic disease requiring long-term management, not a short-term fix 4, 2