Not Losing Weight on a GLP-1? Why It Happens and What to Do (October 2026)

01 · The core answer

Is it normal to not lose weight on a GLP-1?

Yes, a slow or stalled stretch is a common experience, and it is rarely a sign the medicine is broken. Trial figures are averages across many people, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them². Some people lose more than the average and some lose less. The question to ask is not whether you are normal, but which of a short list of causes applies to you.

Start with timing. If you are still on a starter pen, the dose has not yet been built up to the strengths used in the trials. Early pens are designed to let your body settle, so judging the medicine on the starter dose alone is premature.

02 · What to check first

A quick self-check before you change anything

Use this table to match your situation to the most likely cause and the sensible next step. It is a starting point for a conversation with your prescriber, not a diagnosis.

03 · What to do next

What to do if the scales are not moving

First, confirm you are injecting once every week, on schedule, with the pen stored as instructed. Second, write down what you eat and drink for a short run of days, including drinks, snacks and portions. Third, look at your movement: regular moderate activity plus some resistance work is the evidence-backed pattern. Then bring those notes to your next review, because a prescriber can only judge your response with real information.

Do not raise your own dose, add extra injections or combine products you have bought elsewhere. Changes to dose are made by the prescribing team, who can see your history, side effects and other medicines. If you are an existing customer, our ongoing monthly reviews are the right place to raise it. If you are new and want a regulated route, you can start with the free consultation for the Mounjaro pen; the 2.5mg starter pen has a standard price of £169.99, and new customers save £40 on their first order with code FIRST40.

We have separate guides for people on Mounjaro and not losing weight, and for those who feel stuck at 5mg or 10mg. If you want the broader picture of our service, see the weight loss clinic.

One more point: if your weight is dropping far faster than you expected, or you feel unwell with the loss, speak to your prescriber rather than waiting. Report any suspected side effect through the MHRA Yellow Card scheme¹⁹.

Related guides: Why Am I Not Losing Weight On Mounjaro UK: Guide and Not losing weight on 7.5 mounjaro.

04 · Starter doses explained

When do you start losing weight on a GLP-1?

Most people notice appetite changes early, but meaningful weight change usually builds as the dose rises, because starter pens are not designed to deliver the full effect. Mounjaro is a once-weekly injectable medicine made by Eli Lilly, and it comes as a pre-filled multi-dose pen in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ The lowest strength is a way in, not the destination.

Wegovy follows a similar logic with its own ladder of 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg, stepping up after at least four weeks and reaching the 2.4mg maintenance dose from week 17. Both are deliberately gradual so side effects are manageable.

This matters when you read trial results. In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² Those figures came after months on treatment, not after the first few pens, and they differ by dose.

So if you are on the lowest strengths and the scales have barely moved, the likeliest explanation is simply that you have not yet reached the doses at which the bigger averages were seen. That is a reason to stay on schedule and review, not to give up.

It is also a reason not to compare yourself with someone further along. A friend on a higher strength, or someone who started from a different weight, is on a different part of the same curve. Appetite, hunger between meals and how full you feel after eating are often the first signals that the medicine is working, and they can show up before the scales do. Note them down at each review, because they help your prescriber judge whether to step up or hold.

If you have had several months at maintenance-level doses and still feel no change in appetite at all, that is worth a direct conversation. Your prescriber can review injection technique, missed doses, side effects and whether a different licensed option suits you better.

05 · Plateaus and averages

Plateaus, averages and why progress is not a straight line

A plateau is a normal feature of weight loss, and trial results are averages that hide a wide spread of individual outcomes. These are trial averages, individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.² Your own line will have steeper and flatter stretches.

The same trial shows how varied outcomes were. At 72 weeks, 85% of participants on 5mg, 89% on 10mg and 91% on 15mg had lost at least 5% of their body weight.² Half of participants on 10mg and 57% on 15mg lost at least 20% of their body weight.² Read that the other way and it means a share of people lost less than those marks, and some lost less than the average. Falling short of the headline number is part of the picture, not proof you are doing it wrong.

Why does progress slow? As you lose weight your body needs less energy, and the same intake that produced loss earlier may now only maintain you. Scale weight also moves with fluid, salt, hormones across the month, constipation and the timing of weighing, so a flat week does not always mean a flat trend.

Practical ways to judge a plateau fairly:

• Weigh at the same time of day, under the same conditions, and look at the trend over several weeks rather than single readings.
• Track other signals: how clothes fit, appetite, energy and portion sizes.
• Use a free tracker such as our GLPTrackr companion app to see the pattern over time.
• Take your trend, not a single bad day, to your monthly review.

If the trend has been flat for a long stretch despite consistent habits and a settled dose, it is reasonable to ask whether a dose change is appropriate. Higher is not automatically better: the prescriber balances extra effect against side effects and your goals. Some people are content to hold a maintenance dose that keeps weight steady, which is a legitimate outcome in itself.

Finally, remember that Mounjaro works on appetite and digestion, not on your daily choices. Tirzepatide activates GIP and GLP-1 receptors, which help regulate appetite and slow how quickly the stomach empties, so most people feel fuller sooner and less hungry between meals.¹ What you do with that reduced hunger is where results are made.

06 · Food and drink checks

Food and drink: the honest audit

If you are eating less but not losing weight, the gap is usually in what is not being counted, because GLP-1 treatment supports a reduced-calorie diet rather than replacing one. Treatment is used alongside a reduced-calorie diet and increased physical activity.² The medicine lowers appetite, but calorie-dense foods and drinks can still add up quickly when you eat small amounts of them.

Common patterns worth checking, none of which need a calculator:

• Liquid calories. Sweetened coffees, juices, smoothies, alcohol and milky drinks are easy to sip without feeling full, especially when the medicine has slowed stomach emptying.
• Grazing. Small, frequent snacks of soft, easy-to-eat foods are comfortable on treatment and can quietly exceed what a proper meal would have been.
• Softer, lower-effort foods. If heavier meals make you feel unwell, you may drift towards biscuits, crisps and similar foods that sit easily but are calorie-dense.
• Portion creep. Early in treatment small plates feel like plenty; later appetite returns slowly and portions can inch up.
• Weekend and social eating. A few relaxed days can offset a careful week, particularly around alcohol.

A short honest record for a few weeks beats any estimate from memory. Write down meals, snacks and every drink, and review it with your prescriber or a dietitian if you can. You are looking for patterns, not perfection.

Side effects can also shape what you eat. Because the medicine slows how quickly the stomach empties, rich or very large meals may feel uncomfortable, so some people choose whatever feels easiest rather than what is most filling and nutritious. If that sounds familiar, tell your prescriber, who can offer side-effect support and advice on managing it.

Not eating enough is not the goal either. If appetite is very low and you are skipping meals, or you are struggling to take in fluids, speak to your prescriber rather than pushing on; if you feel faint, get medical help straight away. More restriction is not automatically better, and unusually fast loss deserves a check.

Finally, be wary of anything marketed as a shortcut. Low-cost supplements sold with dramatic weight-loss claims have no clinical oversight, dosing is not standardised, and they are not a substitute for the dietary changes that treatment is designed to support.

07 · Movement and muscle

Movement, muscle and sleep on treatment

Increased physical activity is part of the licence, not an optional extra, so a stalled result is a fair reason to look at how much you are moving. Nothing special is required: the evidence-backed pattern is regular moderate activity, such as brisk walking, plus resistance work for muscle.¹ Start where you are and build gradually.

Why resistance work matters on a GLP-1: when you eat less and lose weight, you want that loss to come from fat rather than from muscle. Strength training signals the body to keep muscle, which also helps your energy use, your posture and how your clothes fit. You do not need a gym. Bodyweight exercises, resistance bands, or lifting loads at home all count if done regularly.

On injection days, early side effects may make full sessions unrealistic. Lighter movement still counts, and a walk is better than nothing.¹ Consistency across the whole month matters more than one heroic workout followed by a week of rest.

Exercise also protects against regain if you later stop treatment, which is a good reason to build the habit now while appetite is quieter and motivation is high.¹

Other lifestyle factors can influence the scales:

• Sleep. Poor or short sleep can raise hunger and lower energy for exercise. If you snore heavily or wake unrefreshed, mention it, as sleep problems and weight are linked.
• Stress. Stress can change eating patterns, particularly evening snacking.
• Daily steps. People often move less on treatment because they feel tired or low on energy. A simple step tracker will show whether your general activity has dropped.
• Hydration. Fluid intake can be easy to neglect when appetite is low, and dehydration can make you feel worse and affect the scales.

Build in small, repeatable targets rather than dramatic ones. A realistic weekly routine that you can sustain for months will do more than an ambitious plan you drop after a fortnight. If you are not sure what is safe for your own health, ask your prescriber or GP before starting anything strenuous, especially if you have joint, heart or blood pressure concerns.

If you are tracking, the GLPTrackr companion app can help you log doses, weight and how you feel in one place, which makes your monthly review more productive.

08 · Medical and side-effect factors

Medical factors, side effects and missed doses

If diet, movement and timing all look right and weight still will not shift, it is sensible to ask whether something medical is in the way. The usual areas for a prescriber to explore are thyroid and other hormonal conditions, other medicines that affect weight, sleep problems, and mood or eating patterns. A review with your GP or prescriber can rule these in or out.

Side effects can also interfere. In SURMOUNT-1, 4.3% of people on 5mg, 7.1% on 10mg and 6.2% on 15mg stopped treatment because of side effects, compared with 2.6% on placebo.² Even among those who stay on treatment, nausea or discomfort may change how you eat and move. If you are managing side effects by skipping doses or avoiding food, tell your prescriber, who can adjust the plan and offer side-effect support.

Doses and technique deserve a plain check too:

• Are you injecting once every week, on the same day, without gaps?
• Are you following the pen's instructions each time, including preparation and injection?
• Is your pen stored in the fridge until first use, and kept at 2–8°C before opening? Once in use, a pen can be kept out of the fridge at a temperature not above 30°C for up to 30 days after first use, and must then be thrown away.¹³
• Have you had vomiting or diarrhoea shortly after injecting, and have you told your prescriber?

Other medicines can matter, and some need dose changes when weight falls. If you take medicines for diabetes, for example, your doses may need adjusting because of low blood sugar risk, so this is a prescriber conversation, not something to change yourself. The same applies if you take the contraceptive pill: Mounjaro slows stomach emptying, which can reduce how well oral contraceptive pills are absorbed. The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹

Be honest with your prescriber about everything you take, including supplements. We cannot judge what is not disclosed.

Finally, know what to do if something feels wrong. New or unusual symptoms are not something to wait out. Discuss them with your prescriber and report suspected side effects through the MHRA Yellow Card scheme.¹⁹ Weight that is changing unexpectedly fast, or loss accompanied by feeling unwell, is also worth raising with your prescriber.

09 · Stretching and stopping

Stretching doses, stopping early and what regain looks like

Mounjaro is licensed as a once-weekly medicine, and its blood levels are designed around a 7-day cycle.

Do not add extra injections in the hope of breaking a plateau, or try to combine your treatment with other unlicensed products. A higher dose is not automatically better, and the prescriber is best placed to decide whether a higher licensed dose is appropriate.

What if you are tempted to stop because nothing seems to be happening? Pause before deciding. Mounjaro manages weight; it does not cure the biology behind it. In SURMOUNT-4, people who stopped tirzepatide after 36 weeks regained on average 14% of body weight over the following year, while those who continued treatment lost a further 5.5% on average.¹⁴ Stopping should always be planned with your prescriber, with diet and activity habits ready to carry the load.

That result also shows why a flat patch on treatment is not the same as treatment failing. A stable weight at a lower level may be exactly what the medicine is doing for you, particularly if appetite would otherwise have driven weight back up.

If you do stop, tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system. There is no way to speed this up, and nothing needs doing while it clears.¹ Appetite may return gradually over that time, which is a good moment to have your food and activity habits already in place.

If you are weighing up whether to continue, switch, reduce or stop, our prescribing team can talk it through at your review. The decision is yours, and a planned exit is a legitimate choice. What we would not recommend is an unplanned one, made in frustration at a plateau that may simply need a different approach.

10 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹

11 · Switching and NHS options

Switching treatment, and NHS versus private access

If you have given a settled dose a fair trial and responded poorly, asking about a different licensed option is reasonable, but it is a prescriber decision. GLP-1-type treatments differ. Mounjaro (tirzepatide) activates GIP and GLP-1 receptors at once, which distinguishes it from single-action GLP-1 medicines such as semaglutide, the active ingredient in Wegovy and Ozempic.¹ Ozempic is semaglutide licensed for type 2 diabetes — it is not a UK weight-loss medicine, and a regulated UK pharmacy will not supply Ozempic for weight loss. That is a mechanism difference, not a promise of a different result for you.

Wegovy is a once-weekly semaglutide injection with a ladder of 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg, stepping up after at least four weeks to reach the 2.4mg maintenance dose from week 17.¹⁸ Liraglutide, supplied at 6mg per millilitre, is a daily injection, unlike once-weekly Mounjaro and Wegovy. Your prescriber can advise on which suits you.

Do not switch because a friend responded differently. Responses vary between people and between medicines, and a change should be planned: your prescriber will say what dose to start at and when, based on your history. If you are moving to us from another provider at a higher dose, new customers save £40 on their first order at any dose with code FIRST40, and an automatic £25 reorder discount applies to every future order (code DOSE25).

On the NHS side, Mounjaro is available, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first (initially BMI 40+ with four or more qualifying conditions).⁴⁶ Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting. NHS access to Wegovy runs through specialist weight-management services; ask your GP.

Whichever route you take, make sure it includes follow-up. At EverydayMeds, every order is reviewed by a GPhC-registered prescriber, repeat orders re-check suitability with no auto-shipping, and ongoing monthly reviews, dose titration and side-effect support are part of the service. Mounjaro is supplied through official LillyDirect supply, and delivery is free next-day with same-day dispatch when ordered by 3pm. The consultation is free, and our support team is available Monday to Friday by email, chat or phone. For prices, see the Mounjaro pen prices; all six strengths are in stock. Prices checked 10 October 2026.