How Much Weight Can You Lose on GLP-1?

Quick Answer

The average GLP-1 weight loss is 14.9% on semaglutide (Wegovy) and up to 20.9% on tirzepatide (Zepbound), achieved over 12–18 months. At a 220 lb starting weight, that's approximately 33 lbs on semaglutide and 46 lbs on tirzepatide. Half of semaglutide patients lose more than 15%; half lose less.

Average Results by Starting Weight

Using the clinical trial averages — 15% for semaglutide, 21% for tirzepatide:

Starting Weight	Sema: ~15% Loss	Tirz: ~21% Loss
180 lbs	27 lbs → 153 lbs	38 lbs → 142 lbs
200 lbs	30 lbs → 170 lbs	42 lbs → 158 lbs
220 lbs	33 lbs → 187 lbs	46 lbs → 174 lbs
240 lbs	36 lbs → 204 lbs	50 lbs → 190 lbs
260 lbs	39 lbs → 221 lbs	55 lbs → 205 lbs
280 lbs	42 lbs → 238 lbs	59 lbs → 221 lbs
300 lbs	45 lbs → 255 lbs	63 lbs → 237 lbs
320 lbs	48 lbs → 272 lbs	67 lbs → 253 lbs

Use our Weight Loss Calculator for a personalized estimate with your timeframe.

The Distribution of Results

The 15% and 21% numbers are medians, not limits. The clinical trial data shows a wide distribution:

On semaglutide 2.4 mg (STEP 1):

14% of patients lost less than 5% of body weight (non-responders)
36% lost 5–10%
21% lost 10–15%
19% lost 15–20%
10% lost more than 20%

So roughly 1 in 10 semaglutide patients loses more than 20% of their body weight. About 1 in 7 loses less than 5%.

On tirzepatide 15 mg (SURMOUNT-1):

9% lost less than 5% (fewer non-responders than semaglutide)
25% lost 5–10%
22% lost 10–20%
22% lost 20–25%
22% lost more than 25%

Tirzepatide has a noticeably better distribution — fewer non-responders and more patients in the high-responder range.

Maximum Weight Loss on GLP-1

Maximum weight loss is not a fixed ceiling. In the SURMOUNT-1 trial, some patients lost more than 30% of their body weight on tirzepatide 15 mg. These are exceptional responders — estimated at roughly 5–10% of patients.

What limits maximum weight loss on GLP-1:

The body's adaptive response to caloric restriction (metabolic adaptation)
Dose tolerability ceiling
Competing hormones and compensatory mechanisms
Duration of treatment

Most patients reach their maximum weight loss around 12–18 months and then maintain, rather than continuing to lose indefinitely.

What Determines Your Result?

Medication and dose: Tirzepatide outperforms semaglutide on average. Higher doses within each medication produce more weight loss.

Adherence: Missing doses or not titrating to target dose reduces results.

Diet quality: Patients in trials received nutritional counseling. Optimizing protein intake and reducing ultra-processed foods improves outcomes.

Exercise: Adding resistance training improves body composition (more fat lost, less muscle) even if total weight loss is similar.

Genetics: Some people have naturally better GLP-1 receptor responses. This cannot be predicted in advance.

Diabetes: Having type 2 diabetes reduces average weight loss by approximately 3–5 percentage points.

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Bottom Line

Most people lose 15–21% of their starting weight on GLP-1 medications over 12–18 months. About half will exceed the average; about half will fall below it. A small minority are non-responders. Tirzepatide consistently produces more weight loss than semaglutide across all patient groups.