Case 1.5 – Obesity

Category: Cardiovascular | Discipline: General practice | Setting: Urban Community

Case

Sarah Mitchell is a 42-year-old woman who presents to her GP requesting help with weight loss. She has gradually gained weight over the past 10 years, particularly since having her two children. She currently weighs 95 kg and is 165 cm tall (BMI 34.9). She has tried various diets in the past but has found it difficult to sustain weight loss. She works full-time as an administrative assistant, has little time for exercise, and often relies on convenience foods. Her blood pressure is 138/88 mmHg.

Questions

1. How is obesity defined and classified?

Definition: Obesity is defined as abnormal or excessive fat accumulation that presents a risk to health.

Body Mass Index (BMI) Classification:

Classification	BMI (kg/m²)	Risk of comorbidities
Underweight	<18.5	Low (but risk of other problems)
Normal weight	18.5-24.9	Average
Overweight	25-29.9	Increased
Obesity Class I	30-34.9	Moderate
Obesity Class II	35-39.9	Severe
Obesity Class III	≥40	Very severe

Alternative measures:

Waist circumference: Better predictor of metabolic complications
- Increased risk: Men >94cm, Women >80cm
- Substantially increased risk: Men >102cm, Women >88cm
Waist-to-hip ratio
Body fat percentage

Note: BMI has limitations - doesn't distinguish muscle from fat, may not be accurate for all ethnic groups, very muscular individuals, pregnant women, or elderly.

2. What are the health consequences of obesity?

Obesity is associated with numerous health complications:

Metabolic:

Type 2 diabetes mellitus (risk increases 20-40 fold)
Metabolic syndrome
Dyslipidaemia
Non-alcoholic fatty liver disease (NAFLD)

Cardiovascular:

Hypertension
Coronary heart disease
Stroke
Heart failure

Respiratory:

Obstructive sleep apnoea
Asthma
Obesity hypoventilation syndrome

Musculoskeletal:

Osteoarthritis (especially knees, hips)
Back pain
Gout

Cancer:

Increased risk of multiple cancers: breast (postmenopausal), endometrial, colorectal, kidney, oesophageal, pancreatic

Reproductive:

Polycystic ovary syndrome (PCOS)
Infertility
Complications in pregnancy
Erectile dysfunction

Psychological:

Depression
Low self-esteem
Social stigmatisation

Other:

Gastro-oesophageal reflux disease (GORD)
Gallstones
Venous thromboembolism
Reduced quality of life
Increased all-cause mortality

3. What are the causes of obesity?

Obesity results from an imbalance between energy intake and energy expenditure. The causes are multifactorial:

Primary (Simple) Obesity (\>95% of cases):

Dietary factors: Excessive calorie intake, high-fat/high-sugar foods, large portion sizes, frequent snacking
Physical inactivity: Sedentary lifestyle, reduced occupational physical activity, increased screen time
Genetic factors: Polygenic - multiple genes influence appetite, metabolism, fat distribution. Family history increases risk
Environmental factors: Food availability, food marketing, built environment, socioeconomic factors
Psychological factors: Emotional eating, eating disorders, depression

Secondary Obesity (<5% of cases):

Endocrine disorders:
- Hypothyroidism
- Cushing's syndrome
- Polycystic ovary syndrome
- Growth hormone deficiency
- Hypothalamic damage
Genetic syndromes: Prader-Willi syndrome, Laurence-Moon-Biedl syndrome
Drugs: Corticosteroids, antipsychotics, antidepressants, insulin, sulfonylureas, valproate
Immobility: Following injury or illness

4. What history and examination findings would you obtain from Sarah?

History:

Weight history: Duration of weight gain, maximum/minimum weights, previous weight loss attempts
Dietary assessment: Typical daily food intake, portion sizes, snacking, alcohol, sugary drinks
Physical activity level: Work, leisure, sedentary time
Motivation and readiness to change
Previous weight loss attempts: Methods tried, success, reasons for failure
Barriers to weight loss: Time, financial, social, physical limitations
Psychological factors: Mood, stress, eating behaviours, body image
Secondary causes: Symptoms of hypothyroidism, Cushing's syndrome
Medications that may cause weight gain
Family history of obesity, diabetes, cardiovascular disease
Obesity-related complications: Symptoms of diabetes, sleep apnoea, joint problems

Examination:

Height and weight (calculate BMI)
Waist circumference
Blood pressure
Signs of complications: acanthosis nigricans (insulin resistance), skin tags, varicose veins
Signs of secondary causes: thyroid examination, Cushingoid features, hirsutism
Cardiovascular examination
Joint examination if symptomatic

5. What investigations would be appropriate for Sarah?

Baseline investigations to assess complications and cardiovascular risk:

Fasting blood glucose or HbA1c: Screen for diabetes/prediabetes
Fasting lipid profile: Total cholesterol, LDL, HDL, triglycerides
Liver function tests: Screen for fatty liver disease
Thyroid function tests (TSH): Exclude hypothyroidism
Urea, electrolytes, creatinine: Assess renal function

Additional investigations if clinically indicated:

Sleep study if symptoms of obstructive sleep apnoea
ECG if cardiovascular risk factors present
Urinary free cortisol/dexamethasone suppression test if features of Cushing's

6. What are the principles of weight management?

Goals of treatment:

Initial target: 5-10% weight loss over 6 months (realistic and achievable)
Improve obesity-related complications
Prevent weight regain
Improve quality of life

Multimodal approach - "Three pillars":

1. Dietary modification:

Reduce total calorie intake by 500-600 kcal/day (creates deficit of 0.5-1kg weight loss per week)
Balanced, nutritious diet - not extreme/fad diets
Reduce portion sizes
Reduce high-energy foods (fats, sugars, alcohol)
Increase vegetables, fruits, whole grains
Consider referral to dietitian
Keep food diary

2. Increased physical activity:

Aim for 150-300 minutes moderate intensity activity per week
Start gradually if currently inactive
Find enjoyable, sustainable activities
Include both aerobic and resistance training
Reduce sedentary time

3. Behavioural modification:

Set realistic goals
Self-monitoring (food diary, weight tracking)
Identify and address triggers for overeating
Stress management
Adequate sleep
Social support
Consider cognitive behavioural therapy if indicated

Regular follow-up: Essential for long-term success. Monitor progress, provide support, adjust plan as needed.

7. When should pharmacological or surgical interventions be considered?

Pharmacological therapy:

Consider if lifestyle interventions have failed and:

BMI ≥30 kg/m², OR
BMI ≥27 kg/m² with obesity-related comorbidities (diabetes, hypertension, dyslipidaemia, sleep apnoea)

Available medications:

Drug	Mechanism	Expected weight loss
Orlistat	Pancreatic lipase inhibitor - reduces fat absorption	3-5kg over 12 months. Side effects: GI symptoms, fat-soluble vitamin deficiency
Liraglutide (Saxenda)	GLP-1 agonist - increases satiety	5-10kg. Daily injection. Side effects: nausea, vomiting
Semaglutide (Wegovy)	GLP-1 agonist	10-15kg. Weekly injection. Most effective currently available

Pharmacotherapy should always be combined with lifestyle modification. Continue only if ≥5% weight loss after 3 months.

Bariatric surgery:

Consider if lifestyle and pharmacological interventions have failed and:

BMI ≥40 kg/m², OR
BMI ≥35 kg/m² with significant obesity-related comorbidities

Surgical options:

Gastric bypass (Roux-en-Y): Most effective, 25-30% total body weight loss
Sleeve gastrectomy: 20-25% weight loss
Adjustable gastric band: 15-20% weight loss, less commonly used now

Benefits of surgery:

Significant sustained weight loss
Improvement/remission of type 2 diabetes
Reduction in cardiovascular risk factors
Improved quality of life

Risks: Surgical complications, nutritional deficiencies, need for lifelong follow-up and supplementation.

8. What advice would you give Sarah about maintaining weight loss?

Weight maintenance is often more challenging than weight loss. Key strategies:

Continue healthy eating habits: Don't return to old dietary patterns
Regular physical activity: Often need 200-300 min/week to maintain weight loss
Regular self-monitoring: Weekly weighing, food diary
Plan for high-risk situations: Holidays, celebrations, stress
Seek support: Family, friends, support groups, healthcare providers
Address emotional eating
Regular follow-up appointments: For accountability and support
Be prepared for challenges: Weight loss plateaus are normal
Focus on overall health: Not just the number on the scale

Emphasize that weight management is a lifelong commitment, not a short-term diet. Small lapses are normal - the key is getting back on track quickly.

9. What are the public health implications of obesity?

Obesity is a major public health challenge:

Prevalence:

Worldwide obesity has nearly tripled since 1975
In Australia, approximately 31% of adults are obese, 35% are overweight
Childhood obesity is increasing rapidly

Economic burden:

Direct healthcare costs (managing obesity and related conditions)
Indirect costs (lost productivity, absenteeism, disability)
Estimated costs in billions of dollars annually

Prevention strategies:

Individual level: Education about healthy lifestyle, support for behaviour change
Community level: Improve access to healthy foods, safe environments for physical activity, workplace wellness programs
Government policy:
- Food labeling regulations
- Taxes on sugary drinks
- Restrictions on marketing unhealthy foods to children
- School-based nutrition and physical activity programs
- Urban planning to promote active transport

Addressing obesity requires a coordinated, multi-sectoral approach involving healthcare, education, food industry, and government policy.