Why have I not lost any weight on Mounjaro?

Is Mounjaro even at a dose where weight loss is expected yet?

This is the first question worth sitting with honestly. The treatment schedule for tirzepatide starts at 2.5mg, and that dose has one job: settling your system before the therapeutic work begins. Clinical trial results (including data from the SURMOUNT-1 study, published in the New England Journal of Medicine) showed the largest and most consistent weight reductions at 10mg and 15mg. People on lower doses during titration often see modest or negligible scale changes, and that can feel alarming when you expected results from week one.

Titration typically moves in four-week steps, guided by the prescriber reviewing your response and tolerance. If you are three or four weeks into your first pen and the number has not moved, it may simply be that you have not yet reached the dose where tirzepatide does its substantive work. That is not failure. It is the schedule. Our guide on how Mounjaro works covers the titration pathway in more detail if you want the fuller picture.

The flip side: if you have been at a stable maintenance dose for six weeks or more and nothing has shifted, that is a different conversation, and if you haven't lost any weight on Mounjaro at that stage, it is one worth having with a prescriber rather than letting run on.

Could something else be working against the medicine?

Several factors can blunt or completely obscure weight loss even when tirzepatide is doing exactly what it should. The scales measure total body mass, not fat specifically, so fluid retention (which can spike with stress, poor sleep, high salt intake, or hormonal changes) can cancel out a week's worth of fat loss on paper. Some people also notice a brief weight plateau after a dose increase, which is the body recalibrating rather than the medicine failing.

Eating habits matter too. Tirzepatide reduces appetite and slows gastric emptying, but it does not create a deficit on its own if calorie intake has not fallen meaningfully. A common pattern in practice: appetite suppression kicks in, people feel full quickly, but the foods they do eat are calorie-dense enough that overall intake stays roughly the same. Alcohol is worth checking here, it carries significant calories that often go untracked.

Sleep and cortisol have a more direct effect than most people expect. Consistently poor sleep raises cortisol, which promotes fat storage and can drive hunger in ways that override reduced appetite. None of this is about willpower; it is biology. Our weight-loss overview touches on the lifestyle factors that work alongside treatment.

Finally, certain medications (including some antidepressants, antipsychotics and corticosteroids) can promote weight gain independently, and understanding why you haven't lost weight on Mounjaro sometimes comes down to identifying exactly these kinds of offsetting factors with your prescriber. If you are on other medicines, your prescriber should have this in view.

What does 'not losing weight' actually look like week to week?

There is an important difference between a week with no movement and a genuine plateau. The reasons weight doesn't move in a single week are often mundane: sodium, hydration, the timing of your weigh-in, whether you weighed in after a heavy meal or after a long day. A single static week is not a signal that treatment is failing.

A genuine plateau on Mounjaro is usually defined as four to six consecutive weeks at the same dose with no downward trend at all, when measured consistently at the same time of day. That is the point at which a prescriber would look at whether a dose increase is appropriate, whether there are offsetting factors to address, or whether the treatment is the right fit. The NHS tirzepatide information page is a solid reference for what normal progress looks like and when to flag concerns.

One practical habit: weigh yourself once a week, same morning, same conditions, and track the trend over four weeks rather than comparing Tuesday to Wednesday. The day-to-day noise is significant enough to mislead even when things are going well.

When should you speak to your prescriber rather than waiting?

If you have genuinely not lost any weight over six or more weeks at your current dose, do not simply continue and hope, raise it. Your prescriber can look at whether a dose increase is clinically appropriate, whether your medical history includes anything that might be affecting response, or whether a different approach is needed.

At nume, every repeat order goes through a clinical re-review before anything is dispensed. A prescriber (not an automated queue) reads your update and responds the same day. If you have concerns between orders, our team is reachable seven days a week. It is also worth reading through what to do when Mounjaro isn't working for a structured look at next steps.

For context on what the full treatment process looks like (including how private treatment compares to NHS access on cost) our Mounjaro pricing overview covers it plainly. And if you are considering starting or reviewing your treatment, speaking to our prescribers is the right first move.