Weight loss
How to Calculate Your Weight Loss
Calculating your weight loss is a great way to find out how far you have come.
To calculate the percentage of weight lost, grab a calculator and follow these steps.
The quick and easy way
Your percent weight change is a very quick and easy snapshot of your weight loss as a whole. This quick math that will compare your pre-op weight to your current weight.
(Pre-op weight - Current weight) / (pre-op weight) x 100 = % body weight change
Example: Your pre-op weight was 120 kg, and your current weight is 90 kg
(120 - 90) / (120) x 100 = 25% total body weight loss
The full picture
Calculating your weight loss based on your excess body weight – instead of your weight as a whole – is what is typically used in the bariatric clinic.
It requires a few extra calculations, but it gives us more precise information regarding where you are in your weight loss journey compared with your own healthy range.
There are a few steps, but don’t be intimidated, just follow along:
Step 1
In order to determine your excess body weight, you'll need to find the weight that would put you at a healthy Body Mass Index (BMI) of 25. A healthy BMI ranges from 18-24.9 (for the purpose of this calculation, we will round it to 25).
25 x (height in meter x height in meter) = Weight in kg to be at a BMI of 25
Example: You are 5’5” (1.65 meter)
25 x (1.65 x 1.65) = 68 kg for BMI 25
Step 2
After you have calculated the weight that puts you at a healthy BMI, now it is time to calculate your excess body weight.
Pre-op weight - weight to be at a BMI of 25 = Excess body weight
Example: Your pre-op weight was 120 kg. and you are 5’5”
120 - 68 = 52 kg of excess body weight
Step 3
To calculate the percentage excess body weight loss, use the following formula.
(Number of kg you lost / excess body weight) x 100 = Percent of excess body weight loss
Example: Your excess body weight was 52 kg; You lost 30 kg from 120 kg and your current weight is 90 kg.
(30 / 52) x 100 = You lost 57.7% of excess body weight
That’s it!
With these calculations in place you will be able to better track your progress and continue to work toward your goals.
