Ideal Body Weight (IBW) calculations used in and around weight loss surgery hold special meaning. One might think, incorrectly in this situation, Ideal Body Weight would be an ideal weight after surgery or the “goal” weight after surgery. NOT SO. The ideal body weight calculation we use is based on the New York Life tables from the 1960’s. Actuarials looked at humans at every height, and observed the life span of folks at varying weights for that height. The ideal body weight was the weight of those people who lived the longest.
So, those life tables probably do still have significance – even though the calculations seem “skinny.” We have generally become accustomed to a more plump body habitus.
Bariatric Surgeons use IBW to calculate the amount of weight someone is overweight. Because we all use the same calculation for IBW, the amount of excess weight calculated for each patient is the same in Oklahoma, California, New York, London, Japan etc. In this way, we can compare outcomes in a meaningful way (apples to apples if you will).
IBW is not a goal, but a normalizing number. Only about 1% of people get down to their IBW after bariatric operations. One-half of those folks are in good health, they have just lost a lot of weight; the other half usually has some medical issue – physiologic, psychologic or sociologic.
Bariatric operations in general allow people to lose 55% (band) to 75% (gastric bypass, gastric sleeve) of their excess weight (excess weight = original wt minus IBW). To calculate your Body Mass Index click here.
Entered: Gregory F. Walton, MD, FACS – WeightWise