Weight Loss After Surgery Calculator
In randomized trials, sleeve patients lost about 49% of excess weight at 6 months and 72% at 1 to 2 years. For bypass, about 53% and 77%.
Estimate your weight loss
Excess weight (over BMI 25): 85 lb
| After | Average excess weight lost | You would lose about | Your weight |
|---|---|---|---|
| 6 months | 49.2% | 42 lb | 198 lb |
| 12 months | 72.4% | 62 lb | 178 lb |
| 24 months | 71.9% | 61 lb | 179 lb |
Trial averages, not a promise. The 6-month figure comes from SLEEVEPASS, the 12- and 24-month figures from SM-BOSS, so they are different patients and should not be read as one curve.
Your estimate above uses averages from two randomized trials. In the trials, sleeve patients lost about 49% of their excess weight at 6 months and about 72% at 1 and 2 years. Bypass patients lost about 53% at 6 months and about 77% at 1 and 2 years. The number is an average, so yours may be well above or below it.
Where the numbers come from
| Time after surgery | Sleeve | Bypass | Source |
|---|---|---|---|
| 6 months | 49.2% | 52.9% | SLEEVEPASS, Finland |
| 12 months | 72.4% | 76.7% | SM-BOSS, Switzerland |
| 24 months | 71.9% | 77.4% | SM-BOSS, Switzerland |
| 5 years, for context | 49% to 61.1% | 57% to 68.3% | SLEEVEPASS, SM-BOSS |
Two trials are stitched together here, because no single trial we could open reported all three time points. The jump from 6 to 12 months partly reflects that switch. SLEEVEPASS also found lower numbers at 5 years than SM-BOSS, so treat the results as a range. Both measure loss against a BMI of 25. SLEEVEPASS calls this excess weight loss and SM-BOSS calls it excess BMI loss, but the math is the same. SM-BOSS reported no significant difference between the operations at any point after adjusting for multiple comparisons.
How the calculator works
First, it finds your excess weight: your current weight minus the weight that gives a BMI of 25 at your height. Then it multiplies that by the percentage above. For example, someone 5'6" at 250 pounds has about 95 pounds of excess weight, since a BMI of 25 at that height is about 155 pounds. At 12 months after a sleeve, 72.4% of that is about 69 pounds. That's simple arithmetic, not a prediction.
Percent of excess vs. percent of total
Clinic ads often quote excess weight, because it's the bigger number. Total weight loss is also useful. In a large U.S. study, people lost 25.2% of total weight at one year after a sleeve and 31.2% after a bypass, and 18.8% and 25.5% at five years. Cleveland Clinic gives 25% to 30% of body weight for a sleeve. A patient who starts at 300 pounds and loses 25% loses 75 pounds.
Why your result may differ
- Starting BMI. The trial patients started at a mean BMI of about 44 to 46. Results at other weights may differ.
- Health conditions. People with diabetes lost less on average in the U.S. study.
- Diet, activity and follow-up. The ASMBS calls long-term follow-up essential to good outcomes.
- Time. Some regain is common. Cleveland Clinic says you'll likely reach your lowest weight between one and three years.
Month by month?
Some calculators show a precise figure for each month. We don't, because we found no trial data at those intervals that would support it. MedlinePlus says weight comes off fastest in the first 3 to 6 months. For bypass, it says most people lose about 10 to 20 pounds a month in the first year.
What to do next
- See if you qualify with the BMI calculator.
- Read sleeve vs bypass, and ask your surgeon which suits you.
- Plan your recovery: sleeve or bypass.
Gastric Sleeve (Sleeve Gastrectomy): the U.S. price
Typical U.S. price: From $19,459. Prices abroad and the source.
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Frequently asked questions
How much weight will I lose after a gastric sleeve?
On average about 25% of total body weight at one year in a large U.S. study, or roughly 70% of excess weight in a Swiss trial. Your result will vary.
Is gastric bypass better for weight loss?
On average bypass patients lost somewhat more, especially long term. In SM-BOSS, the gap was not statistically significant after adjustment. Ask your surgeon about your case.
What is excess weight?
The weight above a target. These trials used the weight that gives a BMI of 25 at your height.
Will I regain weight?
Some regain is common. In the U.S. study, sleeve patients went from 25.2% lost at one year to 18.8% at five years.
Sources
- SLEEVEPASS 6-month results (Helmio et al.) — Scandinavian Journal of Surgery, 2014
- SM-BOSS randomized clinical trial (Peterli et al.) — JAMA, 2018
- SLEEVEPASS randomized clinical trial (Salminen et al.) — JAMA, 2018
- Comparative effectiveness and safety of bariatric procedures (Arterburn et al.) — Annals of Internal Medicine, 2018
- Gastric Sleeve Surgery — Cleveland Clinic
- Medical Tourism position statement — American Society for Metabolic and Bariatric Surgery
- Bariatric Surgery — Cleveland Clinic
- Life after weight-loss surgery — MedlinePlus, National Library of Medicine
- Gastric bypass surgery — MedlinePlus, National Library of Medicine