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Correspondence  |   December 2017
Ideal Body Weight Is Not Really Ideal
Author Notes
  • Stanford University Medical Center, Stanford, California (J.B.B.). jbrodsky@stanford.edu
  • (Accepted for publication August 15, 2017)
    (Accepted for publication August 15, 2017)×
Article Information
Correspondence
Correspondence   |   December 2017
Ideal Body Weight Is Not Really Ideal
Anesthesiology 12 2017, Vol.127, 1043-1044. doi:10.1097/ALN.0000000000001883
Anesthesiology 12 2017, Vol.127, 1043-1044. doi:10.1097/ALN.0000000000001883
To the Editor:
As Moreault et al.1  recently discussed in this journal, some anesthetic management guidelines as well as many drug dosing regimens2  are based on a patient’s ideal body weight (IBW). Despite being an important measure in clinical practice, there is no consensus as to what IBW really represents or how to calculate it.3  IBW has no physiologic basis and there is no single weight that is ideal for any patient of a given height.4  For both men and women, IBW often is described as a body mass index (BMI; BMI = kg/m2) between 20 and 25 kg/m2. BMI is not a measure of adiposity because it considers weight irrespective of the source, and excess amounts of fluid, muscle, and bone can each increase BMI.
Given that adipose is poorly perfused and contributes minimally to metabolism, fat-free mass or lean body weight (LBW) would be a better measure for clinical purposes. LBW can be obtained using dual-energy x-ray absorptiometry, but measurements are cumbersome and difficult to apply in clinical medicine.5  The many formulae currently used to estimate IBW give widely different values for the same patient. In the absence of a simple equation for LBW, we agree with Moreault et al. that height (M2) x 22 is a simple formula that can be used clinically to estimate ideal weight.1,4 
Research Support
Support was provided solely from institutional and/or departmental sources.
Competing Interests
The authors declare no competing interests.
Jay B. Brodsky, M.D., Jerry Ingrande, M.D., Harry J. M. Lemmens, M.D., Ph.D. Stanford University Medical Center, Stanford, California (J.B.B.). jbrodsky@stanford.edu
References
Moreault, O, Lacasse, Y, Bussières, JS Calculating ideal body weight: Keep it simple. Anesthesiology 2017; 127:203–4 [Article] [PubMed]
Ingrande, J, Lemmens, HJ Dose adjustment of anaesthetics in the morbidly obese. Br J Anaesth 2010; 105 (suppl 1):i16–23 [Article] [PubMed]
Pai, MP, Paloucek, FP The origin of the “ideal” body weight equations. Ann Pharmacother 2000; 34:1066–9 [Article] [PubMed]
Lemmens, HJ, Brodsky, JB, Bernstein, DP Estimating ideal body weight—a new formula. Obes Surg 2005; 15:1082–3 [Article] [PubMed]
Janmahasatian, S, Duffull, SB, Ash, S, Ward, LC, Byrne, NM, Green, B Quantification of lean bodyweight. Clin Pharmacokinet 2005; 44:1051–65 [Article] [PubMed]