Gastric Sleeve Weight Loss Calculator
Thinking about weight-loss surgery? Enter your height and weight to see your BMI against the latest international guidelines — which use lower thresholds for people of Asian background — and what people starting at your weight lost on average after each type of surgery.
BMI
Enter your height and weight
Weight ÷ height² · thresholds from the 2022 ASMBS/IFSO guidelines
Average results, if you started at kg
| Procedure | After 1 year | After 5 years |
|---|---|---|
Average % total weight loss in the PCORnet Bariatric Study (Annals of Internal Medicine, 2018; about 65,000 US adults with a BMI of 35+). People with diabetes, a BMI under 50 or aged 65+ lost less on average.
These are averages from a US study, not a prediction for you. Whether surgery is right for you — and which kind — is a decision for you and a bariatric surgeon. How you eat before and after surgery matters too, and a dietitian can help with both.
Your results are attached to the form below
These figures are estimates for general awareness only and are not medical advice or a diagnosis. Read our Medical Disclaimer.
Want a Plan Built Around Your Numbers?
A certified dietitian will turn these figures into a diet that fits your routine and your food.
How this is calculated
Average results: mean percentage of total body weight lost at 1 and 5 years after each procedure in the PCORnet Bariatric Study (Arterburn et al., Annals of Internal Medicine, 2018; about 65,000 US adults) — gastric sleeve 25.2% and 18.8%, gastric bypass 31.2% and 25.5%, adjustable band 13.7% and 11.7%. Your projected weight = starting weight × (1 − that percentage). BMI thresholds: 2022 ASMBS/IFSO guidelines — surgery recommended from BMI 35, considered at 30–34.9 with metabolic disease, and for Asian populations offered above 27.5 (BMI over 25 suggesting clinical obesity).
Lower thresholds for Indians
The 2022 guidelines from the American Society for Metabolic and Bariatric Surgery and the International Federation for the Surgery of Obesity note that diabetes and heart disease are more common at a lower BMI in Asian populations. They therefore say a BMI over 25 suggests clinical obesity in Asians, and that surgery should be offered above 27.5 — well below the traditional thresholds.
Reading the averages
The weight-loss figures are averages from a very large US study. In it, people with diabetes, those with a BMI under 50 and those aged 65 or over lost less weight on average. Bypass led to more weight loss than the sleeve but had a higher rate of serious complications in the first 30 days (5.0% against 2.6%).
Diet before and after surgery
Surgery changes how much you can eat, not what your body needs. Getting enough protein, vitamins and minerals from much smaller meals takes planning — a dietitian can help you prepare and adjust afterwards.
More Diet & Nutrition Calculators
See all →- Protein Calculator Find your daily protein requirement using ICMR-NIN 2020, with separate figures for exercise, age 65+, pregnancy and breastfeeding.
- Calorie Deficit Calculator See your maintenance calories and a daily calorie target for weight loss, with two BMR formulas side by side.
- Macro Calculator Split your daily calories into grams of protein, carbohydrate and fat — balanced, higher-protein or your own ratio.
- Calorie Calculator How many calories do you need a day? See three recognised methods side by side — the clinic's, the US standard and India's ICMR-NIN.
- TDEE Calculator Your total daily energy expenditure with four BMR equations compared, and a breakdown of how much goes on rest, digestion and activity.
- Maintenance Calorie Calculator The calories that keep your weight steady — today, and at your goal weight, so you know what to eat once you get there.