Results & Expectations

When Do You See Results?

Find out when people typically start seeing results from Mounjaro or Wegovy, including appetite changes, early progress, and visible weight loss.

Whether you have just started a weight-loss injection or are deciding whether to begin, this guide answers the second-most-asked question in the category: when do you actually see results from Mounjaro or Wegovy? Below is a week-by-week and month-by-month timeline drawn from the published trials, alongside what tends to feel different at each stage. LetsLoseWeight is an independent comparison site; we do not prescribe medication. Individual timelines vary.

The short answer

Most people on Mounjaro or Wegovy notice changes in appetite within 1–2 weeks of starting and visible weight changes within the first month, building through the first 6–9 months as the dose titrates upwards. Weight loss typically plateaus around 12–18 months at trial-average levels.

The two main published trials — SURMOUNT-1 for tirzepatide and STEP 1 for semaglutide — both followed participants for over a year and showed steady, mostly front-loaded weight loss.

Week-by-week: the first month

Week 1: appetite changes start

The first noticeable change for most people is reduced appetite, usually within 5–10 days of the first injection. Common descriptions:

  • "Food noise" quietens — fewer thoughts about snacks between meals
  • Smaller portions feel satisfying
  • Less interest in fatty or sweet foods specifically

Side effects, if they appear, also tend to start in the first week — most commonly mild nausea, sometimes diarrhoea or constipation. See our reduce side effects guide for management strategies.

Week 2: pattern settles

By week 2, most people have a sense of how the medicine feels for them. Side effects from week 1 often start to settle. Weight may begin to drop, but not always — the starter dose (2.5mg Mounjaro / 0.25mg Wegovy) is below the threshold for full clinical effect.

Week 3–4: first weight changes

Visible weight loss typically appears in the second half of the first month. Trial data suggests the average person loses around 1–2% of starting body weight by week 4 — for a 100kg starting weight, that is around 1–2kg.

The first dose increase usually happens at week 5 (Mounjaro to 5mg, Wegovy to 0.5mg). With each step up, side effects may briefly recur — and weight loss tends to accelerate.

Month-by-month: months 2–6

Month 2

Average weight loss by week 8: around 3–5% of starting weight. Side effects from each new dose level generally settle within a week or two. Most patients are now on 5mg Mounjaro or 0.5mg Wegovy and have a clearer picture of how the medicine fits into their lives.

Month 3

Average weight loss by week 12: around 5–8% of starting weight — the threshold often used to define a "clinically meaningful" response. Most patients are now at 7.5mg Mounjaro or 1mg Wegovy.

This is also where many patients start noticing non-scale changes: clothes fitting differently, less reflux, better sleep, easier movement. These often arrive before scale changes feel dramatic.

Months 4–6

Steady continued weight loss through the titration period. By month 6, average weight loss is typically:

  • Mounjaro 10mg: around 12–14%
  • Wegovy 2.4mg (reached by month 4): around 10–12%

Most patients are at or near their maintenance dose by month 6. The titration discomfort phase is largely behind them.

Months 6–12: the steady-loss phase

Months 6 through 12 are typically the most rewarding phase — patients are at a maintenance dose, side effects are manageable, and weight loss continues steadily.

By month 12:

  • Mounjaro 15mg: average around 19–21% of starting weight
  • Mounjaro 10mg: average around 18–19%
  • Wegovy 2.4mg: average around 14–15%

Variation widens during this period. Patients who pair the medicine with structured dietary and activity changes typically end up at the upper end of these ranges; patients without lifestyle changes typically end up nearer the lower end.

For a deeper look at total weight loss expectations, see our how much weight can you lose guide.

Months 12–18: approaching plateau

Weight loss typically slows from month 12 onwards and approaches a plateau by month 18 — the duration of the SURMOUNT-1 and STEP 1 trials. After this, the medicine is mainly maintaining the new lower weight rather than driving ongoing loss for most patients.

This is normal and expected — it is not a sign of treatment failure. The maintenance phase is when the medicine's role shifts from "weight reduction" to "weight maintenance against the body's natural tendency to regain."

Beyond 18 months: long-term

There is less published data beyond 18 months, but a few observations:

  • Some patients continue to lose modest additional weight slowly through year 2
  • Most patients have reached their personal maintenance plateau
  • Continued treatment generally maintains the loss; stopping leads to regain in most patients (Wilding et al., 2022)

The decision about how long to continue is a clinical one, taken with your prescriber based on benefit, side effects, and individual circumstances.

Why timelines vary

Two patients on the same medicine at the same dose can have meaningfully different timelines. The biggest drivers:

  • Starting weight — heavier patients tend to lose more in the first months in absolute terms, though percentages even out
  • Dietary changes — patients who reduce calorie intake meaningfully see faster early loss
  • Physical activity — does not produce dramatic weight changes alone, but supports muscle preservation and metabolic health
  • Adherence to titration — patients who delay or skip dose increases often have slower weight loss
  • Individual responsiveness — some people respond more strongly to GLP-1 medicines than others
  • Other medications and conditions — diabetes, thyroid disease, certain antidepressants, antipsychotics, steroids, and some contraceptive methods can all influence timing

For a fuller list, see our what affects results guide.

What to do if results feel slow

If your weight loss feels slower than the trial averages, a few things are worth checking before assuming the medicine is not working:

  • Are you at a maintenance dose? Below maintenance, results are expected to be slower.
  • How long has it been at the current dose? Effect builds over weeks, not days.
  • Are you in a calorie deficit? The medicine reduces appetite but does not force a deficit if higher-calorie food is still on the menu.
  • Have other lifestyle factors changed? Sleep, stress, alcohol, and activity all influence weight outcomes.

If after 6 months at a maintenance dose your weight loss is less than 5%, talk to your prescriber. Options include: extending time at the current dose, stepping up to a higher dose, switching to a different medicine, or stopping treatment.

What to do at a plateau

A plateau between 12 and 18 months is normal and not a sign that the medicine has stopped working. Strategies that sometimes restart progress:

  • Recheck dietary intake — calorie creep is common
  • Increase protein and reduce ultra-processed food
  • Add or increase resistance training to preserve muscle
  • Discuss a dose adjustment with your prescriber if not already at maintenance

For more detail, see our plateau guide.

Frequently asked questions

Will I lose weight in the first week?
Possibly a small amount, often partly water — meaningful weight loss tends to start by week 2–3. Reduced appetite, however, is usually noticeable within the first week.

Why have I not lost weight in month 2?
At low titration doses (2.5mg Mounjaro, 0.25–0.5mg Wegovy), the medicine is below the threshold for full clinical effect. Real weight loss typically picks up as the dose increases through months 2–4.

When will I look different?
Most people notice clothes fitting differently around month 2–3. More dramatic visible changes typically appear from month 4–6 onwards.

Should I be losing 1kg a week?
No. Trial averages work out to around 0.5–1% of starting weight per week in the first months — for a 100kg starting weight, that is 0.5–1kg per week. Faster loss can drive worse side effects, more muscle loss, and rebound.

Will I plateau and then drop again?
Sometimes — small renewed losses are not unusual after plateaus, particularly with lifestyle adjustments or a dose increase. But most patients reach their personal maintenance plateau by month 18 and stay there while on the medicine.

Next steps

Sources

This guide is for general information only and is not a substitute for professional medical advice. Individual timelines vary considerably.

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When Do You See Results on Weight Loss Injections? | LetsLoseWeight