Lecture on Obesity and Metabolic Syndrome

Introduction

• Discussion on obesity and its link to metabolic syndrome.
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Pathophysiology of Obesity

• Core Concept: Caloric intake exceeds caloric expenditure leading to lipogenesis.
• Adipose Tissue: Accumulation leads to release of cytokines known as adipokines.
  • Key adipokines: Leptin, Resistin, Interleukin 6, Tumor Necrosis Factor Alpha.

Effects of Adipokines

• Insulin Resistance:
  • Inhibits insulin efficacy, resulting in glucose not taken into cells.
  • Leads to hyperglycemia and insulin resistance.
• Cardiovascular Effects:
  • Stimulates renin-angiotensin-aldosterone system and sympathetic nervous system.
  • Causes vasoconstriction leading to hypertension.
• Lipid Metabolism:
  • Increases VLDL production, raising triglyceride levels.
  • Decreases HDL levels, leading to dyslipidemia.
• Central Obesity:
  • Adipokines cause fat distribution in the abdomen, increasing waist circumference.

Metabolic Syndrome

• A condition with at least 3 out of 5 criteria:
  • Hyperglycemia (blood glucose >100 mg/dL), Hypertension, Elevated Triglycerides (>150 mg/dL), Low HDL, Increased waist circumference.
• Obesity is often a prerequisite for metabolic syndrome.

Causes of Increased Caloric Intake

• High-calorie foods.
• Triggers: Stress, depression, certain medications (e.g., corticosteroids, antidepressants, antipsychotics).

Causes of Decreased Caloric Expenditure

• Sedentary lifestyle.
• Metabolic diseases (e.g., hypothyroidism, Cushing syndrome).

Classifications of Obesity

• BMI:
  • Class 1: 30-35
  • Class 2: 35-40
  • Class 3: >40
• Waist Circumference: Used to assess comorbidities.

Long-term Complications

• Hypertension:
  • Caused by increased sympathetic activity and renin-angiotensin system.
• Atherosclerotic Cardiovascular Disease:
  • Due to high VLDL, low HDL, and hyperglycemia.
  • Increases risk of stroke, heart attack, and peripheral artery disease.
• Type 2 Diabetes:
  • Insulin resistance leads to high glucose, polyuria, polydipsia, polyphagia.
  • Diagnostic criteria: A1C > 6.5%, Fasting glucose > 126, Oral glucose tolerance > 200.
• Obstructive Sleep Apnea (OSA):
  • Caused by fat around the neck, leading to airway compression during sleep.
  • Diagnosed with polysomnogram.
• Obesity Hypoventilation Syndrome (OHS):
  • Fat around chest/abdomen reduces lung expansion.
  • Diagnosed with ABG showing high CO2.
• Non-Alcoholic Fatty Liver Disease:
  • Insulin resistance causes fat accumulation in liver.
  • Progresses from steatosis to NASH to cirrhosis.

Treatment Approaches

• Lifestyle Modifications: Reduce caloric intake, increase physical activity.
• Pharmacological Interventions:
  • Orlistat, phentermine-topiramate, GLP-1 agonists (e.g., liraglutide), bupropion-naltrexone.
• Bariatric Surgery:
  • Indicated for high BMI or comorbidities.
  • Types: Sleeve gastrectomy, gastric banding, Roux-en-Y gastric bypass.

Conclusion

• Summary of obesity's pathophysiology and treatment options.
• The importance of addressing both caloric intake and expenditure for effective management.

• The lecture covers detailed mechanisms and clinical implications of obesity and metabolic syndrome, emphasizing the necessity of lifestyle changes and medical interventions.