Adjusted Ideal Body Weight

Used when actual body weight substantially exceeds ideal body weight to avoid overestimating requirements. Clinically useful for nutritional prescriptions in obesity (ESPEN recommends adding 20–25% of excess weight to IBW for energy/protein calculations 1 [Level III evidence]) and for dose calculations where adipose tissue contributes minimally to drug distribution. Helps approximate metabolically active mass when full weight‑based dosing may misrepresent needs.

Start by recognizing it approximates lean‑mass–appropriate dosing when total body weight is excessive. Useful mainly for drug dosing with narrow therapeutic windows.

• Strength: Reduces risk of toxicity when actual body weight would overestimate dose.
• Cautions: Not validated for all drugs; formulas vary; may underdose if used indiscriminately; avoid substituting for clinical judgment or pharmacokinetic monitoring.