Obesity and Metabolic Syndrome

Jun 12, 2024

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Obesity and Metabolic Syndrome

Introduction

  • Obesity and Metabolic Syndrome: Important clinical topics.
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Pathophysiology of Obesity

  • Core Issue: Caloric intake > caloric expenditure.
  • Pathway:
    • Increased caloric intake → Increased fat (adipose tissue).
    • Adipose tissue releases cytokines, especially adipokines.
    • Key adipokines: Leptin, Resistin, IL-6, TNF-alpha.

Adipokines Effects

  1. Insulin Resistance: Adipokines inhibit insulin receptors.
    • Result: Glucose not taken up → Hyperglycemia → Risk of Type 2 diabetes.
  2. Renin-Angiotensin System & Sympathetic Nervous System Activation: Increase in BP, leading to hypertension.
  3. Liver Effects: Increased production of VLDL (triglycerides) and decreased HDL.
  4. Fat Distribution: Central obesity (abdomen) → Increased waist circumference.

Metabolic Syndrome

  • Diagnostic Criteria: Must have at least 3 of the 5 conditions:
    • Hyperglycemia (fasting glucose > 100 mg/dL).
    • Elevated BP (>130/85 mmHg).
    • Elevated Triglycerides (>150 mg/dL).
    • Low HDL (varies by gender).
    • Increased waist circumference (varies by gender).

Causes of Increased Caloric Intake & Decreased Expenditure

  • Increased Intake: High-calorie foods, stress, depression, medications.
    • Corticosteroids, Antidepressants (SSRIs), Antipsychotics.
  • Decreased Expenditure: Sedentary lifestyle, metabolic diseases (Hypothyroidism, Cushing's Syndrome).

Complications of Obesity and Metabolic Syndrome

Hypertension

  • Increased adipokines stimulate renin-angiotensin system & sympathetic nervous system.
  • Diagnosis: Two readings >130/80 mmHg for Stage 1, >140/90 mmHg for Stage 2.

Atherosclerotic Cardiovascular Disease (ASCVD)

  • Adipokines increase VLDL & triglycerides, decrease HDL, increase insulin resistance.
  • Consequences: Increased risk of stroke, myocardial infarction, peripheral artery disease (PAD).

Type 2 Diabetes

  • Adipokines cause insulin resistance → Hyperglycemia.
  • Symptoms: Polyuria, polydipsia, polyphagia.
  • Diagnosis: A1C ≥ 6.5%, fasting glucose ≥ 126 mg/dL, or 2-hour glucose tolerance test ≥ 200 mg/dL.

Obstructive Sleep Apnea (OSA) & Obesity Hypoventilation Syndrome (OHS)

  1. OSA: Fat around neck → Airway compression → Nocturnal hypoxia → Daytime somnolence.
    • Diagnosis: Polysomnogram AHI ≥ 5.
  2. OHS: Fat around chest/abdomen → Impaired lung expansion → Hypercapnia.
    • Diagnosis: ABG showing COâ‚‚ > 45 mmHg, excluding other causes.

Non-Alcoholic Fatty Liver Disease (NAFLD)

  • Pathway: Insulin resistance → Free fatty acid influx → Liver steatosis → Inflammation → Fibrosis → Cirrhosis.
  • Presentation: Jaundice, ascites, altered liver function tests (LFTs).

Diagnosis of Obesity and Metabolic Syndrome

  • Obesity: Defined by BMI.
    • Class 1: 30-35
    • Class 2: 35-40
    • Class 3: >40
  • Metabolic Syndrome: Based on the presence of specific criteria (WAIST mnemonic).

Management

Lifestyle Modifications

  • Reduce food intake, increase physical activity.
  • Goals: Decrease glucose, BP, triglycerides, increase HDL, reduce waist circumference & BMI.

Pharmacological Therapy

  • Candidates: BMI > 30.
  • Medications:
    • Orlistat: Inhibits lipase, reduces fat absorption.
    • Phentermine/Topiramate: Appetitite suppression.
    • GLP-1 Agonists (e.g., Liraglutide): Multiple mechanisms including appetite suppression, increased insulin.
    • Bupropion/Naltrexone: For patients with depression/addiction.

Bariatric Surgery

  • Candidates:
    • BMI ≥ 40, or BMI ≥ 35 with comorbidities.
  • Types:
    • Sleeve Gastrectomy: Reduces stomach size.
    • Gastric Banding: Compresses stomach.
    • Roux-en-Y Gastric Bypass: Small stomach pouch, bypasses duodenum to reduce absorption.
  • Goals: Restrict food intake, decrease nutrient absorption.