Check for a sustained plateau
A few days at the same weight, or a small rise after a meal, is no sign of treatment failure. Fluid, bowel contents, the menstrual cycle and the way you weigh yourself all move the scale. Compare like-for-like readings across several weeks.
Constipation is common on tirzepatide. If it affects your comfort or bowel habit, treat it as a health problem. More medicine or less food is the wrong answer to a scale reading caused by constipation.
Your energy needs fall as you lose weight
A smaller body uses less energy, and your activity may change during treatment. An eating pattern which first produced weight loss may later hold your weight steady. This says nothing about your honesty or effort. Use the change as a prompt to review your current routine.
A dietitian or clinician can review what you eat without pushing you into extreme restriction. If your appetite is already low, eating even less puts your nutrition at risk. Keep strength, daily function and wellbeing in the review.
Check your treatment history
Write down the actual dose, how long you have been on it, missed injections, gaps and any concerns about the pen or storage. If you changed provider, make sure the new one has the full history. One hungry day is no proof of a faulty pen.
Think about new medicines, illness, poor sleep, stress and reduced mobility. A plateau is a pattern to interpret, with no single fix. Sometimes the most useful change lies outside your weight-management prescription.
A higher dose is one option among several
Your clinician decides whether to increase the dose, based on benefit and side effects. The licensed schedule sets minimum gaps between increases and an adult maximum of 15 mg weekly. Never shorten the gaps, combine medicines or draw extra doses from a pen to get round those limits.
If you have marked nausea, constipation or poor intake, you need a review of side effects before any increase. Stronger appetite suppression is no guarantee of better health. Your goal may also have moved from further loss to keeping weight off.
The formal review point
NICE and the UK product information call for a benefit-risk review if you have lost less than 5% of your starting weight after six months at your highest tolerated dose. A temporary plateau does not count as failure under this rule. You do not have to reach the maximum strength.
Take a short record to your appointment: weight trend, symptoms, dose dates and changes in daily life. Agree the next step and when you will review the result. If the plateau follows a good reduction, your weight is being maintained and a steady plan may suit you best. If the benefit stays too small, discuss alternatives. Nobody should blame you or promise the next pen will work.
Sources
Your own medicine leaflet and prescriber come first. A source from another country does not mean the same rule applies in the UK.
- Mounjaro UK Summary of Product Characteristics, updated September 2026 medicines.org.uk
- NICE: prescribing, reviewing and stopping tirzepatide nice.org.uk
- NICE TA1026: recommendations nice.org.uk
- NHS: constipation nhs.uk
- SURMOUNT-1: tirzepatide once weekly for obesity pubmed.ncbi.nlm.nih.gov
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