Why Has Mounjaro Stopped Working? Understanding Plateaus and Reduced Response

Several factors can explain why Mounjaro — or Wegovy (semaglutide) — appears to stop working, even when you are still taking it consistently.

The body adapts

Over time, the body can adjust to a lower calorie intake and a reduced appetite, causing metabolism to become more efficient at a lower weight. This is a normal physiological response and is not unique to GLP-1 medicines. It is one of the main reasons weight loss tends to slow after initial progress.

Dose stage and titration

Mounjaro is typically started at a lower dose and increased gradually under prescriber guidance. If your response has plateaued, your prescriber may review whether your current dose is still appropriate for your circumstances — but any decision about dose is entirely theirs to make, not something to adjust independently. If you feel your medicine has stopped working, the right step is to raise this with your prescriber or doctor.

Lifestyle and behaviour changes

Reduced food noise and appetite suppression can lead to unconscious changes over time — portion sizes may creep back up, activity levels may shift, or sleep quality may deteriorate. These changes can all influence the scale even when the medicine is working as intended. Tracking food intake, sleep, steps, and energy levels can make these patterns visible rather than invisible.

Other contributing factors

Stress, hormonal changes, medications, and underlying health conditions can all affect how weight responds during treatment. None of these are things to self-diagnose; they are worth discussing openly with your healthcare professional.

If you are wondering why Mounjaro does not seem to be working for you specifically, or want to understand more about when Mounjaro typically begins to show results, those pages go into more depth. For a broader look at how the medicine works at a biological level, see our guide to how Mounjaro works.

When progress stalls, data matters. The most useful thing you can do is build a clear, honest picture of what has actually been happening — and that is exactly where GLP Trackr helps.

The app's insights and analytics feature is designed for moments like this. It draws on the data you have already logged — weight, food, sleep, energy, steps — and surfaces correlations and patterns you might not spot day to day. If your protein intake has quietly drifted down, or your sleep quality has worsened around the same time the scale stopped moving, those connections show up. The plateau forecast and daily brief give you a summary that is genuinely useful to bring to your next prescriber appointment.

Alongside insights, the weight and body tracking feature shows your full journey as a chart rather than a snapshot — so you can see whether you are truly plateaued or whether a normal slow period is being magnified by day-to-day fluctuation.

If you are also wondering whether a similar pattern applies on semaglutide, the page on feeling like Wegovy has stopped working covers the same territory for that medicine.

Important: if you are concerned that your medicine is no longer effective, always speak to your prescriber or doctor before making any changes. They know your full history and are the right person to review your treatment — GLP Trackr helps you record and present your journey clearly, but it is not a substitute for that clinical conversation.

Ready to see your patterns more clearly? GLP Trackr is free to try for 7 days on the App Store and Google Play — start logging today and bring real data to your next appointment.