Obesity, Lipids, and Nutrition
Obesity assessment
BMI classifies overweight (25–29.9 kg/m²) and obesity (≥30), with class 3 at ≥40. Waist circumference adds cardiometabolic risk information; thresholds are >40 inches in men and >35 inches in women, with lower cutoffs for some Asian populations. Obesity is a chronic disease, so treatment is staged: intensive lifestyle change, pharmacotherapy for BMI ≥30 or ≥27 with comorbidity, and bariatric surgery for BMI ≥40 or ≥35 with comorbidity. A 5–10% weight loss improves glycemia, blood pressure, and lipids. Nutrition advice should be practical and sustainable, emphasizing reduced saturated fat, refined carbohydrates, and sugar-sweetened beverages rather than a single macronutrient ratio.
Lipid interpretation and treatment
Obtain a fasting or nonfasting lipid panel; calculated LDL-C becomes unreliable when triglycerides exceed 400 mg/dL, so use direct LDL-C or non-HDL-C. Statin intensity is chosen by ASCVD risk and LDL-C level. High-intensity statins include atorvastatin 40–80 mg and rosuvastatin 20–40 mg. An LDL-C ≥190 mg/dL warrants a high-intensity statin regardless of risk score and evaluation for familial hypercholesterolemia. Triglycerides ≥500 mg/dL raise pancreatitis risk and require fibrates, omega-3 fatty acids, and glycemic control. Secondary causes include hypothyroidism, nephrotic syndrome, alcohol use, and medications.
Traps and worked example
Do not attribute muscle symptoms to statins without rechallenge or alternative dosing, and do not use statins during pregnancy. A 52-year-old with LDL-C 195 mg/dL, no diabetes, and a family history of early myocardial infarction should start a high-intensity statin and be assessed for familial hypercholesterolemia. Rule of thumb: when triglycerides are high, non-HDL-C is a more reliable target than calculated LDL-C.