Adjusted Body Weight Calculator and Its Use

Are you trying to lose weight healthily and effectively? Or are you a professional assessing your patients’ nutritional needs? Then this Adjusted Body Weight (AjBW) Calculator is perfect for you!

Dietitians, especially when working with overweight or obese patients, frequently use adjusted body weight (AjBW) to more accurately estimate energy and nutrient needs. This calculator saves time, simplifies the process, and helps make more efficient nutritional decisions for both individual users and health professionals.

Below, you will learn the formula for adjusted body weight, how it is calculated, and when it should be used.

⚠️ Note: We strive to make our Omni Calculators as accurate and reliable as possible. However, this tool cannot replace professional medical advice. If you have any health concerns, please consult a doctor.

What is Adjusted Body Weight?

Adjusted Body Weight (AjBW) is a metric used to calculate nutritional needs, particularly recommended for overweight or obese individuals.

Actual body weight consists of lean mass (muscle, organs, etc.) and fat mass. However, fat tissue is metabolically less active than lean tissue. Therefore, calculating energy needs based solely on actual body weight for obese individuals may result in overestimation. Adjusted body weight provides a more balanced and realistic estimate.

How to Calculate Adjusted Body Weight?

📌 Formula:

$$\text{AjBW} = \text{IBW} + 0.4 \times (\text{ABW} – \text{IBW})$$

• AjBW: Adjusted Body Weight

• IBW: Ideal Body Weight

• ABW: Actual Body Weight

📏 Ideal Body Weight (Using Robinson Formula):

• For men:
  $52 \, \text{kg} + 1.9 \, \text{kg per inch over 5 feet}$

• For women:
  $49 \, \text{kg} + 1.7 \, \text{kg per inch over 5 feet}$

💡 Note: 1 foot = 30.48 cm → 5 feet = 152.4 cm

Example Calculation

Scenario:
A male patient, 180 cm tall, weighing 90 kg.

1. Height conversion:
   180 cm = 5 feet 11 inches → 11 inches over 5 feet

2. Ideal Body Weight (IBW):
   $52 + (11 \times 1.9) = 52 + 20.9 = 72.9 \, \text{kg}$

3. Adjusted Body Weight (AjBW):
   $72.9 + 0.4 \times (90 – 72.9) = 72.9 + 0.4 \times 17.1 = 72.9 + 6.84 = 79.74 \, \text{kg}$

✅ This person should be considered 79.74 kg when planning a nutrition program.

How to Use the Calculator?

1. Select your gender.

2. Enter your height.

3. Enter your actual body weight.

The calculator automatically computes your ideal body weight using the Robinson formula and then shows your adjusted body weight.

🔍 Note: Other formulas for IBW exist (Devine, Miller, Hamwi, etc.), but differences are minimal. We use the widely recognized Robinson formula.

When Should It Not Be Used?

Adjusted body weight is not always appropriate. It should not be used in the following cases:

❌ 1. Athletes or Individuals with High Muscle Mass

Their “excess” weight comes from muscle, not fat. AjBW would be misleading.
➡️ Use FFMI (Fat-Free Mass Index) instead.
→ Check our FFMI Calculator
→ Check our BMI Calculator

❌ 2. Pregnancy

Weight gain during pregnancy is natural and necessary. Nutritional needs should be calculated based on gestational age, not adjusted body weight.
→ Visit Pregnancy Weight Gain Calculator

Frequently Asked Questions (FAQ)

🔹 How do I calculate my Adjusted Body Weight?

Use the formula:
AjBW = IBW + 0.4 × (ABW – IBW)
Find IBW using the Robinson formula for your gender.

🔹 What is the AjBW formula for obesity?

It is the same:
AjBW = IBW + 0.4 × (ABW – IBW)
This formula gives a more realistic estimate for obese individuals’ nutritional needs.

🔹 What is the ideal weight for a woman 1.65 m tall?

• 1.65 m = 165 cm = 5 feet 5 inches

• 5 inches over 5 feet

• IBW = 49 + (5 × 1.7) = 57.5 kg