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GLP-1 Calculators

GLP-1 Weight Loss Timeline in 2026 — STEP, SURMOUNT, and SCALE Projection

Month-by-month weight-loss trajectory on semaglutide, tirzepatide, or liraglutide — anchored to STEP 1, SURMOUNT-1, and SCALE endpoints.

Updated April 2026

Medical disclaimer: This tool is for informational purposes. Not medical advice. Consult your healthcare provider before starting, stopping, or changing any medication. Drug prices, savings cards, and coverage policies change frequently — verify current pricing directly with the manufacturer or your pharmacy.

Your inputs

Results

Weight at month 12
196 lbs
34.5 lbs total loss
Avg loss/month
2.9 lbs
Projected weight trajectory

The endpoints everyone should know

  • STEP 1: semaglutide 2.4 mg vs placebo in overweight/obese without diabetes. N=1,961, 68 weeks. TBWL 14.9% vs 2.4%. 86% achieved ≥5%; 50% achieved ≥15%.
  • STEP 2: semaglutide in T2D. TBWL 9.6% on 2.4 mg, 7.0% on 1.0 mg. Lower than non-diabetes cohort.
  • SURMOUNT-1: tirzepatide 5/10/15 mg vs placebo. N=2,539, 72 weeks. TBWL 15.0% / 19.5% / 22.5% vs 3.1%. 96% of 15 mg achieved ≥5%; 63% achieved ≥20%.
  • SCALE: liraglutide 3.0 mg daily in overweight/obese adults. 56 weeks, mean TBWL ~8%.

The shape of the curve, month by month

  • Month 1 (starter dose): 2–4 lb, mostly appetite dampening and water.
  • Month 3 (therapeutic dose): 5–8% TBWL on sema; 7–10% on tirz 10 mg.
  • Month 6: 9–12% on sema; 13–17% on tirz 15 mg.
  • Month 9: 12–14% on sema; 18–20% on tirz 15 mg.
  • Month 12: 13–16% on sema 2.4 mg; 20–22% on tirz 15 mg.
  • Month 16–18 (nadir): 14–15% sema; 22–23% tirz.

What drives variance from trial means

  • Tolerance of escalation: patients who reach and maintain top dose hit the ceiling; submaximal plateauers lose correspondingly less.
  • Adherence: 2024 claims analysis showed <25% of commercial GLP-1 prescriptions completed 12 months continuous therapy.
  • Layered diet and training: patients who add structured diet + resistance training outperform drug-alone trial arms.
  • T2D status: T2D cohorts lose ~30–40% less on the same drug.
  • Concurrent meds: SSRIs, olanzapine, some mood stabilizers blunt loss.

What happens when you stop

STEP 4 (withdrawal arm): semaglutide continuers lost another 8% over 48 weeks; placebo switchers regained roughly two-thirds of lost weight. SURMOUNT-4 showed similar pattern for tirzepatide (14% regain at 52 weeks). Conclusion: GLP-1 therapy is chronic. Plan accordingly.

Related tools
BMI trajectory
52-week BMI plot by therapy.
Goal weight timeline
When you hit your target.
Dosage schedule
When you reach each step.
Stopping regain
What happens after.
Plateau breaker
When loss stalls.
Muscle loss risk
Body composition matters.

Frequently asked questions

How much will I lose in the first month on Wegovy?

Typically 2–5 lb at the 0.25 mg starter dose — which is not a therapeutic dose. Don't judge the drug by the first month. The therapeutic benefit shows up once you reach 1.0 mg (week 9–12) and then continues climbing through 1.7 mg and 2.4 mg.

Will I lose more on Zepbound than Wegovy?

On average yes. SURMOUNT-1: 22.5% TBWL on tirzepatide 15 mg at week 72 vs STEP 1's 14.9% for semaglutide 2.4 mg at week 68. SURMOUNT-5 (direct head-to-head) confirmed tirzepatide superiority by ~6.5 percentage points. Individual variation is large, but the population signal is clear.

Why isn't my loss matching the STEP 1 curve?

STEP 1 enrolled patients without diabetes, with good adherence, measured in the per-protocol population. Real-world factors — T2D, adherence gaps, concomitant meds (SSRIs, olanzapine blunt loss), titration holds — predictably shift individual results. If you're 3+ percentage points below expected at month 6 on top dose, discuss with your prescriber.

Is faster loss better?

No. Faster loss correlates with more lean-mass loss. Aim for 1–2 lb/week during therapeutic-dose months, accept slower during titration and maintenance. Protect muscle via resistance training and 1.2–1.6 g/kg goal-weight protein. Weight lost from fat is your goal; weight lost from muscle compromises your post-loss metabolism.

Do I need to stay on the drug after I reach my goal?

For most patients, yes. GLP-1 is a chronic treatment for a chronic disease. STEP 4 showed 6.9% regain at 48 weeks post-stop. Some patients successfully taper to lower maintenance doses (0.5–1.0 mg semaglutide, 5–7.5 mg tirzepatide). See the maintenance dose tool.

When does the plateau typically arrive?

For semaglutide, week 40–50. For tirzepatide 15 mg, week 50–60. This is the drug's dose ceiling, not a failure. Options: (1) switch drugs (sema to tirz adds 5–7% TBWL), (2) accept new set point, (3) layer combination therapy, (4) review adherence — often apparent plateau is calorie creep as appetite suppression adapts.

What does waist circumference tell me that the scale doesn't?

Waist measurement (morning fasted, at navel, tape level) is a cleaner visceral-fat-loss signal and usually leads scale trends by 1–2 weeks. STEP 1 reported 13.5 cm mean waist reduction. Target 2 cm/month during therapeutic-dose months. < 1 cm for 3 consecutive months is a troubleshooting signal (adherence, protein, sleep).

What percent of weight loss comes from muscle?

Without intervention: 20–40% of total mass lost is lean tissue — higher than bariatric surgery (~25%) and much higher than resistance-training + high-protein programs (< 15%). For a 50 lb total loss at 22.5% TBWL, that's 10–15 lb of fat-free mass. Countermeasure: 1.2–1.6 g/kg protein and 2–4 resistance sessions/week covering squat, hinge, push, pull, carry.

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