Ideal Body Weight Calculations for Medication Dosing

Clinical Applications

For obese patients (BMI > 30 kg/m²), using ideal body weight rather than actual body weight helps prevent overdosing of medications, as recommended by the American Society of Anesthesiologists 1
When administering intravenous lidocaine, ideal body weight should be used for dose calculation, which can be determined using the formula for men: IBW = (height in cm - 100) and for women: IBW = (height in cm - 105), according to the Anaesthesia guideline 1
For patients with normal BMI (18.5-24.9 kg/m²), actual body weight and ideal body weight are similar, as stated by the American Heart Association 1

BMI-based ideal body weight calculations do not account for differences in body composition, potentially misclassifying individuals with high muscle mass, as noted by the American Heart Association 2, 3
BMI has good specificity (90-99%) but poor sensitivity (36-50%) for detecting obesity, meaning many individuals with excess body fat may have a normal BMI, according to the American College of Cardiology 2