Adjusted Body Weight Calculator – Calculate AjBW

Calculate your adjusted body weight using various ideal body weight formulas with the AjBW calculator.

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Ideal Body Weight:
 
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How to Calculate Adjusted Body Weight

Adjusted body weight (AjBW) is a calculation adjustment for someone’s actual body weight when they are overweight or obese. Calculations of calorie needs are then based on adjusted body weight rather than actual body weight.

AjBW is sometimes used instead of a person’s actual weight because adipose tissue, or fat tissue, has a lower metabolic rate than lean muscle tissue. Therefore, using actual body weight has the potential to overestimate calorie needs in this population.

Even though there is logic behind using AjBW, it is important to note that there are some inconsistencies in the research about whether calorie needs should be estimated using adjusted versus actual body weight.[1]

When to use adjusted body weight

There are several circumstances under which health professionals have historically used the adjusted body weight formula. One of the most common reasons is for calculating calorie needs for overweight or obese individuals.[2]

To determine if AjBW may be appropriate, first start by calculating your ideal body weight. If your actual body weight is greater than or equal to 125% of your ideal body weight, then you may consider using AjBW when calculating calorie needs.[2]

If your actual body weight is less than 125% of your ideal body weight, it is recommended to use your actual body weight when calculating calorie needs.

Adjusted Body Weight Formula

The adjusted body weight formula looks like this:

AjBW = ((ABW- IBW) × 0.25) + IBW

where:
ABW = actual body weight
IBW = ideal body weight

As a disclaimer, there are a few slightly different equations for AjBW amongst the research. The above equation is the most commonly cited from the research.

Example of how to use the adjusted body weight formula

Follow the steps below to calculate the adjusted body weight for a female who wants to lose weight and is 5’5″ and weighs 210 lbs:

First, determine the ideal body weight by using the ideal body weight calculator.

Using the Hamwi formula for ideal body weight, this individual has an ideal body weight of 125 lbs.

Based on this number, her actual body weight of 210 lbs is 168% of her ideal body weight. Given this is greater than 125% of her ideal body weight, she would be a candidate for using the adjusted body weight formula.

We will now use her actual and ideal body weight to determine her adjusted body weight.

Actual body weight = 210 lbs
Ideal body weight = 125 lbs

Adjusted body weight (AjBW) = (ABW-IBW) x 0.25) + IBW

AjBW = (210 lbs – 125 lbs) × 0.25) + 125 lbs
AjBW = (85 lbs × 0.25) + 125 lbs
AjBW = 21.25 lbs + 125 lbs
AjBW = 146.25 lbs

Then, you can use the adjusted body weight of 146.25 lbs in the weight loss calculator to estimate calorie needs.

Adjusted Body Weight vs. Ideal Weight

Ideal body weight is an estimate of what an individual’s weight should be based solely on a person’s height and gender. However, it is not practical to assume that everybody with the same height will also be the same weight.

Unlike ideal body weight, adjusted body weight considers a person’s actual weight in addition to their height and gender. This makes AjBW a more individualized and likely more realistic formula, especially when calculating calorie needs for weight loss.

When to Use Adjusted Body Weight – Limitations

As previously mentioned, there are inconsistencies on whether or not AjBW should be used when calculating calorie needs. In fact, The Academy of Nutrition and Dietetics has recommended against using this calculation and instead recommends using actual body weight with the Mifflin St Jeor equation.[1]

If you do choose to use the adjusted body weight formula, it should not be used for individuals whose excess weight is related to muscle mass or pregnancy.

References

  1. Academy of Nutrition and Dietetics, Adjusted or Ideal Body Weight (IBW) for Nutrition Assessment?, https://www.eatrightpro.org/news-center/nutrition-trends/nutrition-assessment/adjusted-or-ideal-body-weight-for-nutrition-assessment
  2. Lahner, C. R., Adult weight measurement: decoding the terminology used in literature, South African Journal of Clinical Nutrition, 2018, 32(2), 28–31. https://doi.org/10.1080/16070658.2018.1426186