GLP-1 Weight Loss | Ozempic & Wegovy Timeline

GLP-1 Weight Loss Calculator: Timeline & Projections for Ozempic, Wegovy, Mounjaro, Zepbound

STEP averaged ~14.9% loss on Wegovy 2.4 mg over 68 weeks; SURMOUNT ran higher on Zepbound at 15 mg. Enter your weight and dose to see what those study means might look like in months, including an optional slowdown in months 4–6.

What the projection shows

The tool turns published trial loss percentages into a weekly rate for your starting weight, then counts forward to your goal. Plateau mode shaves the rate by ~30% during weeks 16–26 (months 4–6) when many people report a stall. Output is months to goal, pounds left, BMI at goal, and the trial % tied to your medication and dose.

Example:

248 lb today, 200 lb goal, on 1.7 mg Wegovy with plateau on: you might see something in the mid-teens of months, not a single “68 weeks for everyone” answer, because the rate scales with your weight and the dose tier you picked.
Not medical advice:

Published averages only. It does not diagnose, prescribe, or tell you which drug to use. Talk to your clinician before starting, stopping, or changing dose.

How the Math Works

The projection model derives a weekly loss rate from published clinical trial data. Each medication and dose carries a reference percentage, for example, Wegovy 2.4 mg showed approximately 14.9% mean body-weight loss over 68 weeks in the STEP 1 trial. The weekly rate for any starting weight is:

\text{rate} = \frac{\text{start weight} \times \text{trial \%}}{\text{trial weeks}}

Time to goal follows directly:

\text{weeks to goal} = \frac{\text{weight to lose}}{\text{weekly rate}}

Worked example: a 250 lb person on Wegovy 2.4 mg → rate = (250 × 0.149) ÷ 68 ≈ 0.548 lbs/week; losing 40 lbs takes roughly 40 ÷ 0.548 ≈ 73 weeks. When the plateau toggle is enabled, the calculator slows the rate by approximately 30% during weeks 16–26 (months 4–6) to model the metabolic adaptation many users experience. These projections use population-level averages; individual results vary based on adherence, diet, physical activity, and genetics.

Reading the estimate

Match the dose you actually inject this week, not the maintenance dose you are titrating toward. Turn plateau on if months 4–6 already feel flat on the scale; it lengthens the timeline in line with common reports, not because the drug quit working. Compare drugs or doses using the month count and trial % together, and judge progress over 8–12 week windows instead of daily noise.

How GLP-1 Drugs Work for Weight Loss

GLP-1 Receptor Agonists

GLP-1 agonists (semaglutide, tirzepatide) mimic a gut hormone that curbs appetite and slows gastric emptying. Ozempic and Wegovy are semaglutide; Mounjaro and Zepbound are tirzepatide, which also targets GIP receptors.

Ozempic & Wegovy (Semaglutide):

Ozempic is approved for Type 2 diabetes at 0.25–2 mg weekly. Wegovy is approved for obesity at up to 2.4 mg weekly. STEP trials showed mean weight loss of ~14.9% over 68 weeks at the highest dose.
Mounjaro & Zepbound (Tirzepatide):

Tirzepatide is a dual GLP-1/GIP agonist. Mounjaro is for diabetes; Zepbound is for obesity. SURMOUNT trials showed ~15–21% mean weight loss over 72 weeks depending on dose (5, 10, or 15 mg).
Mechanism:

Weight loss occurs primarily through reduced calorie intake, the drugs make it easier to eat less. They do not directly burn fat. Diet and physical activity still matter for long-term success.

Using This Calculator by Medication

Using this as a Wegovy weight loss calculator

Pick Wegovy and the dose you inject now. Titration often takes about 16 weeks before 2.4 mg maintenance, so early months can look slow on the scale even when appetite has already dropped. Typical steps: 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg, roughly four weeks apart. If plateau mode adds time, that usually tracks the months 4–6 stall people describe, not a dead drug.

Using this as a Zepbound weight loss calculator

Zepbound uses the same tirzepatide backbone as Mounjaro but is labeled for obesity. Trial means run higher at 10–15 mg than semaglutide at 2.4 mg, so the month estimate can look shorter at the top dose tier. Waves still happen: dose increases, water shifts, and the mid-course slowdown can flatten a week without erasing a quarter.

Using this as an Ozempic weight loss calculator

Ozempic is semaglutide at diabetes dose tiers (often below Wegovy’s 2.4 mg obesity cap), so the projected line is usually gentler. That is dose math, not a verdict on whether you are "responding." If you are comparing Ozempic off-label loss to a friend on Wegovy, compare dose and trial %, not just brand names.

Using this as a Mounjaro weight loss calculator

Mounjaro is tirzepatide for Type 2 diabetes; SURMOUNT-style obesity numbers are the reference for Zepbound, but the weekly mg tiers overlap. Use the dose on your pen today. Off-label weight-loss use is common in conversation, but only your prescriber can say whether Mounjaro versus Zepbound fits your situation.

What Affects Weight Loss Rate & Why Results Vary

Factors That Influence Outcomes

Trial curves are averages. Your line moves with starting weight, dose, adherence, and how much of the early drop was water.

Starting Weight & BMI:

Higher starting weight may correlate with greater absolute loss; percentage loss varies by individual.
Medication & Dose:

Tirzepatide at higher doses generally produces greater mean loss than semaglutide in trials. Dose escalation and maintenance matter.
Lifestyle:

Diet quality, physical activity, sleep, and stress all influence outcomes. Medication supports, not replaces, lifestyle changes.
Genetics & Adherence:

Response varies by genetics. Missing doses or stopping early affects results.

Understanding the Plateau: Months 4–6

Why Progress Often Slows

Many GLP-1 users notice a slowdown or stall in months 3–6. This is common and does not necessarily mean the medication has stopped working. Want to compare GLP-1 projections against traditional caloric deficit models? Use our Calorie Calculator.

Metabolic Adaptation:

As you lose weight, your body burns fewer calories. The same deficit produces slower loss.
Water Weight:

Initial rapid loss often includes water. As that stabilizes, weekly loss may appear smaller.
Dose & Time:

Dose escalation takes weeks. You may not yet be at your maintenance dose. Plateaus can also precede another drop.
What to Do:

Discuss with your provider. Avoid changing dose on your own. Focus on consistency, diet, activity, and adherence, rather than day-to-day scale changes.

Clinical Trial Data: STEP & SURMOUNT

Cited Sources

We derive weekly loss rates from trial percentages: rate = (start weight × p%) ÷ trial weeks; weeks to goal = weight to lose ÷ rate. Trial data:

STEP Trials (Semaglutide/Wegovy):

STEP 1–5 evaluated semaglutide 2.4 mg for obesity. Mean weight loss ~14–17% over 68–104 weeks. Ozempic (lower doses) showed smaller mean loss.
SURMOUNT Trials (Tirzepatide/Zepbound):

SURMOUNT 1–2 evaluated tirzepatide 5, 10, 15 mg for obesity. At 15 mg: ~21% mean weight loss over 72 weeks. At 10 mg: ~19.5%; at 5 mg: ~15%.
Limitation:

Trial populations may differ from real-world users. Individual results vary. This calculator provides estimates only.

GLP-1 Weight Loss Calculator FAQ

How long does it take to lose 50 lbs on Wegovy?

At the STEP trial rate of ~14.9% mean weight loss over 68 weeks, a 250 lb person would lose ~37 lbs in 68 weeks. For 50 lbs, timeline depends on starting weight: a 350 lb person might approach 50 lbs in ~68 weeks; a 220 lb person would take longer (since 14.9% of 220 is ~33 lbs). With plateau adjustment (30% slower during months 4–6), add roughly 4–6 months. Individual results vary; use this calculator with your weight for an estimate.

What is a GLP-1 plateau and how do I break it?

A GLP-1 plateau is a period when weight loss slows or stalls, often around months 4–6. Causes include metabolic adaptation (fewer calories burned at a lower weight), reduced water loss, or not yet being at maintenance dose. To break it: stay consistent with injections and diet; discuss dose titration with your provider; increase protein and resistance training to preserve muscle; and avoid drastic calorie cuts. Plateaus are common, they don't mean the drug has stopped working. This calculator includes a plateau adjustment to model that slowdown.

Is Mounjaro more effective than Ozempic for weight loss?

Yes. In clinical trials, tirzepatide (Mounjaro/Zepbound) produced greater mean weight loss than semaglutide (Ozempic/Wegovy). SURMOUNT showed ~20.9% mean loss over 72 weeks at 15 mg vs STEP's ~14.9% for Wegovy 2.4 mg over 68 weeks. Mounjaro is also approved for diabetes; Zepbound is the obesity-specific formulation. Both are dual GLP-1/GIP agonists. Individual response varies, consult your provider to choose the right medication.

How does starting weight affect my timeline?

Higher starting weight typically means more absolute pounds lost (e.g., 14.9% of 300 lbs = 45 lbs vs 14.9% of 180 lbs = 27 lbs). This calculator uses trial-based percentage loss, so the weekly rate scales with your starting weight. Your timeline to a goal weight depends on how many pounds you need to lose and your medication/dose. Diet, exercise, and adherence also affect your personal timeline.

Can I use this calculator for Rybelsus (oral semaglutide)?

Rybelsus is oral semaglutide at lower daily doses (3–14 mg); trials showed less mean weight loss than injectable Wegovy (2.4 mg weekly). This tool is built for injectable Ozempic, Wegovy, Mounjaro, and Zepbound. For Rybelsus, Wegovy is a rough proxy at best; expect a longer timeline. Ask your prescriber what to expect on oral semaglutide.

What happens to my weight if I stop GLP-1 medication?

Clinical trials and real-world data show that most people regain a significant portion of lost weight after stopping GLP-1 medications. These drugs support reduced appetite and calorie intake; when you stop, appetite often returns and weight can come back. Maintenance strategies include gradual dose tapering (under provider guidance), sustained lifestyle changes (diet and exercise), and sometimes continued low-dose therapy. This calculator does not model post-cessation weight changes, discuss long-term planning with your healthcare provider.

GLP-1 Weight Loss Calculator: Timeline & Projections

Weight & goals

Medication

Estimates

GLP-1 Weight Loss: What Clinical Trials Actually Show

GLP-1 Reality Check

How GLP-1 Drugs Work

Clinical Trial Averages vs You

The Plateau Window

Why We’re Careful