Monitoring BMI after Surgery



What is BMI?

BMI is a simple way to determine if your body is healthy in relation to your height. It provides an estimate of total body fat and your risk of developing weight-related diseases.

The formula for BMI is:BMI = Weight (kg)/Height (m)².

BMI ranges

The BMI ranges for weight classification in adults are:

< 18.5 Underweight

18.5–24.9 Healthy weight range

25.0–29.9 Overweight

30.0–34.9 Obesity I

35.0–39.9 Obesity II

≥ 40.0 Obesity III


BMI for weight losssurgery

Gastric band, gastric sleeve or gastric bypass patients have a starting BMI of 35 or above. The criterion for these surgeries is either: a BMI of 35 plus and a medical condition like high blood pressure and diabetes that may improve after weight loss or, a BMI of 40 plus and morbidly obese.

The BMI for gastric balloon patient’s is 27 or above.

You’ll use this BMI measurement as your benchmark when monitoring your BMI.

Set yourself regular,realistic and achievable BMI goals

Weight loss surgeries, alongside a programme of exercise and diet control, are highly effective at helping obese people to reduce their BMI levels. Working with your bariatric surgery team you can set weight and BMI target milestones to reach.

Monitor your BMIweekly

It’s recommended that you weigh yourself weekly and use thisto determine your BMI using the BMI calculator.

Paying close attention to the numbers on the scale and the associated BMI often helps bariatric surgery patients to lose weight and remain motivated. Regular checking of your BMI allows you to see where you are on your weight loss journey. You can see how much your weight and BMI have reduced and how far you have to go to reach your next target.

Also when weekly weigh-ins and BMI observations become a habit you’re more likely to notice any weight gain and increase in BMI and this will help you get back on target.

Use your BMI data to celebrate your successes

Celebrate when you reach your BMI goals. Achieving these significant milestones reinforces that you’re on track and successfully progressing through your weight loss journey, keeping you motivated to continue losing weight in the knowledge that you can do it.

Weight loss plateau

By regularly monitoring your weight and BMI you may find you reach a weight loss plateau. As you progress through your weight loss journey,your body will adapt to a stricter diet and exercise program. Also as fat turns to muscle your weight may stabilise as muscle is heavier than fat. You shouldn’t become despondent by this but use it to evaluate your progress and re-assess your diet, exercise and lifestyle.

Your weight loss goals

In general, gastric bypass patients lose around 70% of their excess weight, sleeve gastrectomy patients lose around 60%, gastric banding patients lose around 50% and those with a gastric balloon lose up to 30% their excess weight. However, the amount of weight lost by each patient will vary depending on individual circumstances.

In terms of BMI you’ll be aiming to ultimately achieve a healthy BMI between 18.5 and 24.9.

About Ramsay Health Care gastric banding surgery

Ramsay Health Care is a leading provider of weight loss surgery in the UK and offers weight loss procedures performed by highly qualified and experienced bariatric surgeons who have undergone intensive specialist training in their specialty.

Please contact us if you would like to discuss any of our weight loss procedures in more detail.

Please note that all copy above does not reflect views or opinions of Ramsay Health Care UK unless explicitly stated. This information does not replace advice from medical professionals.

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