Understanding your gastric sleeve weight loss projection
Bariatric surgery outcomes are reported using percent excess weight loss (%EWL), not pounds lost alone, because it accounts for how much weight a person had to lose in the first place. This calculator applies that standard formula to your own numbers so you can see excess weight, a projected weight loss at a chosen outcome level, and the resulting projected weight and BMI.
How the calculation works
- Current BMI is your weight in kilograms divided by your height in meters squared - the same formula used across clinical BMI screening.
- Goal weight is calculated from your goal BMI (25 by default, the upper edge of the "normal" BMI range) applied to your height: goal weight = goal BMI x height in meters squared.
- Excess weight is your current weight minus that goal weight - the amount of weight bariatric studies use as the denominator for %EWL.
- %EWL is weight lost divided by excess weight, multiplied by 100. Losing 100% of excess weight means reaching the goal-BMI weight.
What a realistic outcome looks like
Published outcome studies for laparoscopic sleeve gastrectomy commonly report average %EWL in roughly the 50 to 70 percent range by 12 to 18 months after surgery. This calculator lets you compare a lower (45%), typical (60%), and higher (70%) scenario within that commonly reported range so you can see how sensitive the projected outcome is to the assumption.
What this projection does not capture
Actual results depend on surgical technique, adherence to post-surgical nutrition and activity guidance, metabolic and hormonal factors, and follow-up care - none of which a weight-and-height calculator can see. Some patients regain a portion of excess weight after the initial loss period; this tool models a single projected point, not a full multi-year trajectory.
When to consult a professional
This tool performs the standard %EWL arithmetic for planning and education. It is not a substitute for guidance from a bariatric surgeon or dietitian, who can set expectations based on your full medical history and surgical plan.