67. Obesity and metabolic syndrome X - classification, etiology, pathogenesis, clinical manifestations.

Obesity and metabolic syndrome X – classification, etiology, pathogenesis, and clinical manifestations.

• Obesity: Excessive accumulation of body fat that may impair health; usually defined as BMI ≥ 30 kg/m² .
• Metabolic syndrome X: A cluster of metabolic abnormalities increasing cardiovascular risk.

Classification

Obesity (by fat distribution)

Obesity (by cause)

Etiology

Obesity

• Genetic predisposition (polygenic or monogenic).
• Environmental/lifestyle factors:
• High-calorie diet.
• Sedentary lifestyle.
• Endocrine causes (less common):
• Hypothyroidism.
• Cushing’s syndrome.
• Hypothalamic injury (e.g., trauma, tumor ).

Metabolic syndrome X

• Strongly linked to central obesity.
• Insulin resistance is central feature.
• Genetic susceptibility and lifestyle factors contribute.

Pathogenesis

Obesity

1. Chronic energy intake exceeds expenditure → adipocyte hypertrophy and hyperplasia.
2. Visceral fat particularly active → releases free fatty acids, cytokines, adipokines.
3. Promotes insulin resistance, low-grade inflammation, and atherogenesis.

Metabolic syndrome X

1. Central obesity → insulin resistance.
2. Insulin resistance → hyperinsulinemia → impaired glucose uptake → hyperglycemia.
3. Lipid abnormalities:

• Increased triglycerides.
• Decreased HDL cholesterol.

4. Increased blood pressure via sodium retention and vascular changes.
5. Prothrombotic and proinflammatory state.

Clinical manifestation s

Obesity

• Increased body fat → visible weight gain.
• Fatigue, decreased exercise tolerance.
• Mechanical complications:
• Osteoarthritis (especially knees, hips).
• Sleep apnea, hypoventilation syndrome.
• Gastroesophageal reflux.
• Varicose veins.

Metabolic syndrome X (criteria)

Typically includes at least three of the following:

• Abdominal obesity:
• Waist circumference >102 cm in men, >88 cm in women.
• Hyperglycemia:
• Fasting glucose ≥100 mg/ dL (or diabetes diagnosis).
• Hypertension:
• BP ≥130/ 85 mmHg or on treatment.
• Hypertriglyceridemia:
• TG ≥150 mg/ dL.
• Low HDL cholesterol:
• <40 mg/ dL (men), <50 mg/ dL (women).

Systemic complications

• Type 2 diabetes mellitus.
• Atherosclerosis → increased risk of myocardial infarction, stroke.
• Non- alcoholic fatty liver disease (NAFLD).
• Increased cancer risk (e.g., colon, breast, endometrial).