What is the body mass index for a 170 cm tall, 92.5 kg adult and what first‑line management should be recommended?

BMI Calculation and Classification

For an adult with height 170 cm and weight 92.5 kg, the BMI is 32.0 kg/m², which classifies as Class I obesity, and first-line management should be a comprehensive lifestyle intervention for 6-12 months targeting a 5-10% weight loss through caloric reduction of 500-750 kcal/day, at least 150 minutes weekly of moderate-intensity physical activity, and behavioral therapy with at least 14 sessions over 6 months. 1, 2

BMI Calculation

• BMI = weight (kg) / height (m)² = 92.5 / (1.70)² = 32.0 kg/m² 1, 3
• This falls into Class I obesity (BMI 30-34.9 kg/m²) according to WHO classification 1, 3

Risk Assessment Required Before Treatment

You must assess for cardiovascular risk factors and obesity-related comorbidities before initiating treatment, as their presence mandates intensive management regardless of weight loss efforts. 1, 3

Essential screening includes:

• Blood pressure measurement to identify hypertension 1, 3
• Fasting glucose and HbA1c to detect diabetes or prediabetes 3
• Lipid panel (triglycerides, HDL-C) for dyslipidemia 3
• Waist circumference: >102 cm (men) or >88 cm (women) indicates increased cardiometabolic risk 1, 3
• Assessment for sleep apnea, fatty liver disease, and other obesity-related conditions 1
• Weight history: patterns of gain/loss, previous attempts, family history of obesity 1, 3
• Medication review to identify drugs contributing to weight gain 3, 4

First-Line Treatment: Comprehensive Lifestyle Intervention

Dietary Modification

Reduce caloric intake by 500-750 kcal/day to achieve 0.5-1 kg weight loss per week, targeting an initial 5-10% body weight reduction over 6 months. 1, 2, 4

• Eliminate sugary drinks and ultra-processed foods 4
• Increase fruits and vegetables while reducing high-fat and high-sugar foods 4
• Consider portion control strategies such as meal replacements or pre-packaged meals to improve adherence 4

Physical Activity

Engage in at least 150 minutes per week of moderate-intensity aerobic activity (such as brisk walking) or 75 minutes of vigorous-intensity activity, combined with resistance training at least 2 days per week. 1, 2

• For individuals with BMI >35 kg/m², choose activities that do not burden the musculoskeletal system 1
• Reduce sedentary behaviors (TV watching, computer use) 1
• Physical activity is crucial for long-term weight maintenance but may be less effective for initial weight loss 4

Behavioral Therapy

Participate in at least 14 sessions of intensive behavioral therapy over 6 months, focusing on self-monitoring, nutrition education, and cognitive restructuring. 4

• Weekly or more frequent self-weighing for accountability 2
• Behavioral therapy typically produces 5-10% weight loss, with maximum loss occurring between 6-12 months 4

When to Add Pharmacotherapy

If weight loss is less than 5% after 3-6 months of lifestyle intervention, consider adding FDA-approved anti-obesity medications (orlistat, liraglutide, semaglutide, naltrexone/bupropion, or phentermine-topiramate). 1, 2, 4

• Pharmacotherapy is indicated for BMI ≥30 kg/m² or BMI ≥27 kg/m² with weight-related complications 1
• Medications must always be used in conjunction with lifestyle modification, never as monotherapy 4
• Continue medication only if the patient loses at least 5% of initial body weight during the first 3 months or at least 2 kg during the first 4 weeks 1

Bariatric Surgery Consideration

Bariatric surgery should be considered if BMI reaches ≥40 kg/m² or ≥35 kg/m² with obesity-related comorbidities after failure of non-surgical interventions. 1, 2

• At current BMI of 32.0 kg/m², this patient does not yet meet surgical criteria unless significant comorbidities develop 1
• Surgery requires comprehensive multidisciplinary assessment and long-term follow-up for at least 2 years 1

Long-Term Management Strategy

Obesity must be treated as a chronic disease requiring ongoing management, not a temporary condition. 1, 2

• Most weight loss occurs in the first 6 months; if weight regain occurs after stopping treatment, restart the intervention program 5
• Long-term follow-up programs (≥1 year) with regular physical activity (200-300 min/week) are essential for weight maintenance 2
• Take a daily multivitamin at bedtime if using orlistat due to fat-soluble vitamin malabsorption 5

Common Pitfalls to Avoid

• Do not rely on BMI alone for risk assessment—it does not distinguish muscle from fat or capture central adiposity patterns 3, 6
• Do not skip waist circumference measurement in patients with BMI <35 kg/m², as it provides additional cardiovascular risk information 1, 3
• Do not delay intensive management of cardiovascular risk factors (hypertension, dyslipidemia, diabetes) while pursuing weight loss 1, 3
• Do not use person-last language—say "person with obesity" rather than "obese person" 2
• Do not set unrealistic expectations—a 5-10% weight reduction produces significant clinical benefits even if it seems modest 2, 4