Tirzepatide Results: Average Weight Loss by Week

Quick Answer

Tirzepatide (Zepbound/Mounjaro) at 15 mg produces an average 20.9% body weight loss over 72 weeks. The weekly trajectory is: roughly 5% by week 12, 12% by week 24, and 18–21% by week 72. At the 5 mg dose, average results are 15% — comparable to semaglutide but with a faster early trajectory.

Weekly Weight Loss Trajectory for Tirzepatide

From the SURMOUNT-1 trial (72-week, n=2,539, tirzepatide 15 mg vs placebo):

Timepoint	Avg % Lost (15 mg)	Avg lbs (250 lb start)
Week 4	~2.5%	~6 lbs
Week 8	~5.0%	~12 lbs
Week 12	~7.5%	~19 lbs
Week 20	~12.5%	~31 lbs
Week 28	~15.5%	~39 lbs
Week 40	~18.5%	~46 lbs
Week 52	~20.0%	~50 lbs
Week 72	~20.9%	~52 lbs

Tirzepatide shows a faster early trajectory than semaglutide at comparable dose-response stages, likely due to the additive GIP receptor activation.

Results by Dose at 72 Weeks

Dose	Avg Weight Loss	Lost ≥20%
5 mg	-15.0%	32%
10 mg	-19.5%	51%
15 mg	-20.9%	57%
Placebo	-3.1%	1%

The dose-response relationship is clear and substantial. There's approximately 3–4 percentage points of additional weight loss with each dose step up (5 → 10 → 15 mg).

Tirzepatide vs. Semaglutide Results Side-by-Side

Timepoint	Tirzepatide 15 mg	Semaglutide 2.4 mg
Week 12	~7.5%	~5.3%
Week 24	~12.5%	~8.4%
Week 52	~20.0%	~14.0%
Final	~20.9%	~14.9%

Tirzepatide's advantage is apparent from early timepoints and widens over the course of treatment. At week 52, tirzepatide at 15 mg produces roughly 6 percentage points more weight loss than semaglutide 2.4 mg.

The High-Responder Story

One of the most striking tirzepatide findings is the frequency of exceptional response:

36% of patients on 15 mg lost more than 25% of body weight
Some patients lost 30–35% of body weight — territory previously associated only with bariatric surgery
The SURMOUNT-1 authors noted that approximately 1 in 3 tirzepatide patients achieved surgical-level outcomes

This is unprecedented for a pharmacological intervention and substantially changes the ceiling for what medication can achieve.

Tirzepatide Results With Diabetes

SURMOUNT-2 tested tirzepatide 15 mg in adults with type 2 diabetes:

Average weight loss: -14.7% at 72 weeks
5% loss was achieved by 85% of patients
10% loss by 68%

Diabetes reduces tirzepatide response by about 6 percentage points — the same ratio seen with semaglutide. Even at this reduced efficacy, tirzepatide's diabetes results exceed semaglutide's obesity results in many head-to-head comparisons.

Sustained Results: The SURMOUNT-4 Withdrawal Study

SURMOUNT-4 studied what happens to tirzepatide patients who stop after 36 weeks of treatment:

Patients who continued: maintained their -20%+ weight loss through 88 weeks
Patients who switched to placebo: regained ~14 lbs (about 2/3 of lost weight) within 52 weeks of stopping

This confirms that tirzepatide, like semaglutide, requires ongoing treatment to sustain results.

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Bottom Line

Tirzepatide produces the most weight loss of any currently approved medication — 20.9% average at 15 mg over 72 weeks, with 36% of patients losing more than 25%. Results build progressively over 12–18 months and are maintained with continued treatment. For patients who can access it, it is the single most effective non-surgical weight loss option available.