obesity
Summary
Obesity is defined as a BMI ≥30 kg/m² and represents excessive body fat accumulation that increases health risks. It's a major risk factor for cardiovascular disease, type 2 diabetes, and metabolic syndrome. Central obesity (increased waist circumference) is particularly associated with insulin resistance and metabolic complications.
Detail
Obesity results from chronic energy imbalance where caloric intake exceeds expenditure, influenced by genetic, environmental, and behavioral factors. Pathophysiologically, excess adipose tissue, particularly visceral fat, produces inflammatory cytokines (TNF-α, IL-6) and adipokines (leptin, resistin) that promote insulin resistance and chronic inflammation. This leads to metabolic dysfunction including dyslipidemia, hypertension, and glucose intolerance. Obesity is classified as Class I (BMI 30-34.9), Class II (BMI 35-39.9), and Class III/severe (BMI ≥40). It significantly increases risk for coronary artery disease, stroke, type 2 diabetes, obstructive sleep apnea, nonalcoholic fatty liver disease, certain cancers, and osteoarthritis. Central adiposity measured by waist circumference (>40 inches in men, >35 inches in women) is a better predictor of metabolic complications than BMI alone. Treatment involves lifestyle modifications (diet, exercise), behavioral therapy, pharmacotherapy (orlistat, GLP-1 agonists), and bariatric surgery for severe cases.
Sources
- Harrison's Principles of Internal Medicine
- Williams Textbook of Endocrinology
- First Aid for the USMLE Step 1
- UpToDate Clinical Decision Support
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