Mounjaro not working or a plateau: what to do next
A Mounjaro plateau is normal: weight loss slows for almost everyone as the months go on. Before you change anything, check it is a real plateau and not a slow week, then look at the four things you control: protein, steps, strength training and what you are actually eating. Here is how to tell, and what to do next.
Your dose, and whether the medicine is right for you, are for your prescriber. This guide is about the training and food around it.
By Simon, head coach at Zama Fitness. Updated 24 October 2026.
Is it a Mounjaro plateau or a slow week?
Your weight moves by a kilo or more from day to day with water, salt, food in your gut and your cycle. One flat week tells you very little.
- Weigh in on the same days, first thing, after the toilet, before food.
- Compare four-week averages, not one day against another.
- Measure your waist once a month. If it is shrinking, you are still losing fat.
If the four-week average has not moved for a month or more, that is a real plateau.
Why weight loss slows on Mounjaro
In the main tirzepatide trial, SURMOUNT-1, weight came off fastest in the first months and slowed as the 72 weeks went on. That is what happens with any weight loss, with or without medicine:
- A lighter body burns less, so the gap between what you eat and what you burn gets smaller.
- Appetite creeps back as you get used to the medicine, and portions grow without you noticing.
- Movement drops. Less energy on a small intake often means fewer steps.
- Muscle lost along the way lowers your burn further, if you are not strength training.
Mounjaro not working: what to check first
"Mounjaro not working" can mean two different things. If you lost weight and then stopped, it is usually a plateau, and the checks below are where to start. If you have lost little or nothing after several months, speak to your prescriber: people respond differently, and whether the medicine and your dose suit you is their call.
For a plateau, check these in order:
- Protein. Are you getting enough at every meal? It protects muscle and keeps you full.
- Steps. Has your daily count dropped since you started? It is the easiest thing to put back.
- Strength training. Two or three sessions a week keeps the muscle that keeps your burn up.
- What you eat, honestly. Write down a normal week, including drinks, bites and weekends.
- Sleep and alcohol. Both affect appetite and how much you move the next day.
How to lose more weight on Mounjaro
The answer is rarely to eat even less. Many people on the medicine already eat very little, and cutting further costs muscle, which makes the next stall more likely. Fix the basics first:
- Set a protein target from your weight: our protein calculator has an option for people on weight-loss medication.
- Check your calories against your maintenance now, not when you started: the calorie calculator works it out.
- Pick a daily step target a little above your current average, and hit it most days.
- Start or keep strength training: see how to lose weight on Mounjaro without losing muscle.
- Give each change four weeks before you judge it.
When to speak to your prescriber
- You have lost little or no weight after several months.
- You are struggling to eat enough, or feel faint, dizzy or unwell.
- You are thinking about changing your dose, or stopping.
How we help
Zama Fitness runs a separate support plan for people losing weight with prescribed medication, reviewed by a registered dietitian and working alongside your prescriber. You get protein and calorie targets, a strength programme and meals set for you, and every four weeks your coach looks at your weight, waist and strength trend and changes the plan. We do not prescribe medication.
Thinking ahead? Coming off Mounjaro and keeping the weight off.
Mounjaro plateau: your questions.
Why has my weight loss stopped on Mounjaro?
Usually because your body now needs fewer calories than when you started, so the same amount of food no longer makes a big enough gap. Eating back up as you get used to the medicine, moving less and losing muscle all add to it. Water retention can also hide fat loss for a week or two.
How long does a Mounjaro plateau last?
A pause of a week or two is normal and often ends on its own. If your four-week trend has been flat for a month or more, it is worth checking your food, steps and training, and speaking to your prescriber.
What if Mounjaro is not working at all?
Most people in the main trial lost at least 5% of their weight, but not everyone did, and people respond differently. If you have lost little or nothing after several months, speak to your prescriber about whether the medicine and your dose are right for you.
How can I lose more weight on Mounjaro?
Get enough protein, keep a daily step count, strength train two or three times a week, and check what you are actually eating for a week. Most stalls come from one of those four slipping.
Should I eat less to break a Mounjaro plateau?
Not straight away. Many people on Mounjaro already eat very little, and cutting further costs muscle and makes the next stall more likely. Check protein, steps and training first.
Can I be gaining muscle and losing fat on Mounjaro?
If you have just started strength training, yes, it is possible for a while, and the scales can stall even though your waist is shrinking. That is why we track waist and strength as well as weight.
A coach, a plan and a monthly review, from £29.
No joining fee. Cancel online in two clicks. Places open in January.
Core
£29a month
Your programme, nutrition targets and a monthly Weigh-In Day report.
Coached
£59a month
Everything in Core, plus your coach reads every check-in.