Is tirzepatide better than semaglutide for weight loss?

Clinical trials show tirzepatide (Mounjaro/Zepbound) produces greater average weight loss — approximately 20–22% of body weight — compared to semaglutide's (Wegovy) 15%. However, both medications show significant individual variation, and tolerability, cost, and insurance coverage differ between the two.

What happens when you stop taking GLP-1 medication?

Studies show that most people regain approximately two-thirds of their lost weight within a year of stopping GLP-1 medications. This indicates the medication works by suppressing appetite rather than permanently altering metabolism, and many people require long-term use.

GLP-1 Weight Loss Timeline Calculator – See Your Results Month by Month

See exactly how much weight you could lose — month by month — on semaglutide (Ozempic/Wegovy) or tirzepatide (Mounjaro/Zepbound). Projections based on published Phase 3 clinical trial data.

How this calculator works

This tool uses published weight loss data from the largest GLP-1 clinical trials to model a personalized weight loss curve over 24 months. For semaglutide, projections are derived from the STEP 1 trial (n=1,306), which showed a mean weight loss of 15.3% at 68 weeks. For tirzepatide, we use the SURMOUNT-1 trial (n=2,539), which demonstrated 20.9% average weight loss at 72 weeks on the highest approved dose.

Rather than a single endpoint, we map the loss curve across 24 months, reflecting the real-world pattern: faster loss in the titration phase (months 1–6), peak rate during maintenance (months 6–9), then a gradual plateau.

Clinical context: The "average" results shown here come from highly controlled trial conditions with structured diet and exercise support. Real-world results can be higher or lower depending on adherence, diet quality, dose level, and individual metabolism.

Semaglutide vs. Tirzepatide: What the data shows

Both medications work by mimicking gut hormones that regulate appetite. Tirzepatide activates two receptors (GLP-1 and GIP), while semaglutide activates one (GLP-1). In head-to-head analyses and cross-trial comparisons, tirzepatide consistently shows greater weight loss — but there are important trade-offs.

Metric	Semaglutide (Wegovy)	Tirzepatide (Zepbound)
Avg. weight loss	~15.3%	~20.9%
Trial duration	68 weeks	72 weeks
Placebo loss	2.6%	3.1%
Branded US price/mo	~$1,350 (Wegovy)	~$1,060 (Zepbound)
Compounded price/mo	$200–$400	$250–$500
FDA-approved for obesity	Yes (Wegovy)	Yes (Zepbound)

Factors that affect your results

Dose titration speed

Both medications start at a low dose and increase every 4 weeks. Most weight loss occurs after reaching maintenance dose. Patients who titrate slowly (often to manage nausea) typically see delayed results in months 1–3 but similar long-term outcomes.

Diet quality

GLP-1 medications suppress appetite, but they don't eliminate the need for dietary choices. In STEP 1, all participants received structured dietary counseling. Studies comparing GLP-1 users with and without dietary support show approximately 4–6% additional weight loss with active diet management.

Exercise

Exercise has a modest additional effect on total weight loss with GLP-1 medications but a significant effect on body composition. Resistance training during GLP-1 use is particularly important to preserve lean muscle mass, as GLP-1-driven weight loss can include a higher proportion of muscle than other methods.

Starting BMI

People with higher starting BMIs tend to lose more absolute weight, though percentage loss is relatively consistent across BMI ranges. Those with metabolic conditions like insulin resistance or PCOS may respond differently.

Frequently asked questions

This calculator uses average weight loss percentages from large-scale Phase 3 clinical trials (STEP 1 for semaglutide, SURMOUNT-1 for tirzepatide). Individual results vary significantly based on diet, exercise, dose adherence, and individual metabolism. Use these projections as a planning range, not a guarantee.

On average, people lose 1–2 lbs per week in the first 3 months on semaglutide, and slightly more on tirzepatide. Loss typically peaks around months 4–8 before plateauing. Most clinical trials show the greatest percentage loss in months 3–9 as the dose is titrated to maintenance level.

Clinical trials show tirzepatide produces greater average weight loss (~20–22% of body weight) compared to semaglutide (~15%). However, individual responses vary widely, and factors like tolerability, cost, and insurance coverage may influence which medication is right for you. Both require a prescription and medical supervision.

Most people notice 2–5% weight loss within the first 4–8 weeks. Meaningful results (5–10%) are typically seen by month 3. The greatest rate of loss usually occurs between months 3 and 9 as doses are titrated up to maintenance level.

Studies show that most people regain approximately two-thirds of their lost weight within a year of stopping GLP-1 medications. This indicates these medications work by suppressing appetite rather than permanently altering metabolism — many people require long-term use to maintain results.

The weight loss projections apply to any semaglutide formulation at equivalent doses, including compounded versions. However, compounded medications are not FDA-approved and may have different dosing, purity, and reliability. The FDA declared the semaglutide shortage over in February 2025, which may affect compounded availability.

Explore more tools to plan your GLP-1 journey.

GLP-1 Weight LossTimeline Calculator