Enter your numbers and see exactly when you'll reach your goal on tirzepatide vs semaglutide, modeled on actual clinical trial data. Then flip on nutrition and training to watch the dates jump forward.
In trials of FDA-approved branded preparations: tirzepatide (SURMOUNT-1, 72 weeks) produced an avg 20.9% body-weight reduction; semaglutide (STEP-1, 68 weeks) produced 14.9%. In head-to-head data (SURMOUNT-5, NEJM 2025), branded tirzepatide produced roughly 50% greater weight loss than branded semaglutide. Compounded preparations are not FDA-approved. Pairing either molecule with structured nutrition and resistance training (SURMOUNT-3 / STEP-3) supports faster timelines and lean-mass preservation.
Sources: Jastreboff et al. NEJM 2022 (SURMOUNT-1) · Wilding et al. NEJM 2021 (STEP-1)Both GLP-1 medications produce weight loss along a predictable curve, fast initial drop, gradual deceleration, then a plateau. We fit an exponential approach model to the timepoints from the published trials and solve backward for the date your weight crosses your goal.
Why "+ nutrition and training" moves the date forward, not because the drug works harder, but because adherence is higher, the deficit is larger, and resistance training preserves lean mass so the scale keeps moving instead of stalling at month 4.
GLP-1s suppress hunger; structured eating turns that into a measurable deficit instead of a guess.
Resistance training holds onto lean tissue, meaning the weight you lose is actually fat.
The "month 4 stall" is mostly behavioral. Built-in nutrition tracking pushes through it.
Trial data shows combined protocols hit ~28% reduction vs ~21% for medication alone.
It's a model based on trial averages, useful as a planning tool, not a guarantee. About one-third of trial participants exceeded these results, one-third matched them, and one-third fell short. Your own response depends on dose tolerance, adherence, sleep, training, starting composition, and individual physiology.
Tirzepatide is a dual GIP/GLP-1 receptor agonist; semaglutide acts on GLP-1 alone. The dual mechanism produces stronger appetite suppression and metabolic effects, which translates to roughly 6-10 percentage points more weight loss at the equivalent timepoint. Both work, tirzepatide just works faster on average.
For this calculator: protein at ~1g per pound of target body weight per day, calorie tracking with a moderate deficit (~500/day below maintenance), and resistance training 3-4×/week. That's the protocol matched in the SURMOUNT-3 and STEP-3 lifestyle arms. You don't need to be a bodybuilder, you need consistent inputs.
The calculator still gives you a date, it just extends the curve with a slower "tail" past the modeled plateau, which mirrors what real-world patients experience with sustained adherence and dose adjustments. Goals well past the average are achievable; they just take longer and benefit most from pairing the medication with structured nutrition and resistance training. Our physicians help calibrate dose strategy as you progress.
Yes. The model assumes consistent weekly dosing through standard titration. Real-world adherence drops, side effects pause progress, and life happens, so a small buffer of 4-8 weeks past the projected date is realistic.
Yes, about 30% of trial participants exceeded the mean. Strategies that push past the plateau include dose maximization, switching from semaglutide to tirzepatide mid-cycle, intermittent dose pauses to restore receptor sensitivity, and the lifestyle changes already discussed. Our physicians help calibrate based on your trajectory.
Maintenance. Most patients transition to a lower maintenance dose (e.g., 0.5-1mg semaglutide or 5mg tirzepatide) to defend the loss. Discontinuing entirely without a maintenance protocol leads to ~2/3 weight regain within a year (per STEP-4 trial data). Plan the off-ramp before you reach the goal.
Knowing the goal date is step one. These tools fill in the rest, calories, macros, body composition, hormones, and the long-game biological-age impact.
Hand-picked guides on dosing, plateaus, muscle preservation, and what happens after you hit the goal.
Tirzepatide drives roughly 50% greater weight loss than semaglutide in head-to-head data (SURMOUNT-2, 2023): ~22% vs ~15% body weight over 68-72 weeks. If your timeline matters, the molecule is the difference between hitting your date and missing it.
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How this tool calculates
Projected weight-loss timelines are educational simulations based on aggregate published clinical-trial data for the FDA-approved branded GLP-1 medications (Wegovy/semaglutide in STEP-1, Zepbound/tirzepatide in SURMOUNT-1). The tool illustrates trial-average trajectories. Individual results vary; the tool does not predict outcomes for compounded preparations.
Peer-reviewed sources
Important. This tool is provided for educational purposes only and does not constitute medical advice, diagnosis, or treatment. The tool does not prescribe medication, recommend specific dosing, or substitute for clinical evaluation. Compounded medications referenced anywhere on this site are not FDA-approved; the FDA does not verify the safety, effectiveness, or quality of compounded drugs. Treatment decisions are made only by a licensed U.S. physician after individual patient evaluation.