Sponsored · Compounded GLP-1 not FDA-approved as finished drug · Prices confirmed at intake
About this calculator
How this calculator works
This tool uses published weight loss data from the largest GLP-1 clinical trials to model a personalised 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
~$1,349 (Wegovy)
~$1,059 (Zepbound)
Compounded price/mo
From $146
From $258
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 without adequate protein and strength work.
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 and should discuss realistic expectations with their prescribing physician.
Frequently asked questions
Most people lose 5 to 8% of their body weight in the first 3 months on semaglutide (Ozempic or Wegovy). For a 200-pound person, that is 10 to 16 lbs in the first 12 weeks. The STEP 1 clinical trial showed an average 15% total body weight loss at 68 weeks on the 2.4mg Wegovy dose, with the majority of loss occurring between months 3 and 9. Weight loss in the first month is typically slower as your body adjusts and doses are titrated up. Months 3 through 8 tend to show the fastest loss, often 1 to 2 lbs per week. Individual results vary based on starting weight, dose adherence, diet quality, exercise habits, and individual metabolic response.
Tirzepatide produces greater weight loss than semaglutide. The SURMOUNT-1 trial showed an average 20.9% body weight loss at 72 weeks on the 15mg dose — approximately 52 lbs for a 250-pound person. At 3 months, most people lose 7 to 10% of body weight on tirzepatide. At 6 months, 12 to 15% loss is typical. Tirzepatide works through dual GIP and GLP-1 receptor agonism, which provides stronger appetite suppression than semaglutide alone. The tradeoff is cost: compounded tirzepatide starts around $258 per month compared to $146 per month for compounded semaglutide.
For most people, losing 20 pounds on GLP-1 medication takes 4 to 6 months on semaglutide, or 3 to 5 months on tirzepatide. The timeline depends heavily on starting weight. A 250-pound person losing at the average STEP 1 trial rate of 15% would reach a 20-pound loss around month 5. A 300-pound person would hit that milestone closer to month 4. These are average projections — some people lose faster due to higher starting weight, better diet adherence, or switching to tirzepatide.
Weight loss plateaus on GLP-1 medication are normal and expected, typically occurring around months 6 to 12. When your body reaches a new equilibrium, the appetite-suppressing effect adapts and calorie reduction slows. To break a plateau: first ensure you are at your maximum tolerated dose — most patients plateau prematurely due to staying at lower doses. Second, reassess your calorie intake, as appetite suppression naturally decreases over time. Third, increasing resistance training preserves muscle and sustains metabolic rate. If you have been on the maximum dose for 3 to 6 months without further loss, your provider may consider switching to tirzepatide or adjusting your nutritional approach.
Weight loss from GLP-1 medication is not permanent if you stop taking it. A landmark 2022 study published in Diabetes, Obesity and Metabolism found that participants regained an average of two-thirds of their lost weight within one year of stopping semaglutide. This is because GLP-1 medications work by suppressing appetite and regulating blood sugar — when stopped, these mechanisms revert. An increasing number of clinical guidelines now recommend GLP-1 medications as long-term treatments, similar to blood pressure medication, rather than short-course interventions.
This calculator uses population-average weight loss curves from the STEP 1 trial (semaglutide) and SURMOUNT-1 trial (tirzepatide) — the largest published Phase 3 trials for each medication. Individual results vary significantly: roughly 30% of trial participants lose substantially more than average, and 15 to 20% lose less than projected. The calculator adjusts projections for dosing speed and lifestyle inputs, but cannot account for individual metabolic variation, medication adherence, or dietary changes. Use the results as a planning tool and directional estimate, not a guarantee.
Start GLP-1 from $146/moYucca Health · Doctor-prescribed