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When it slows down
Weight loss on a GLP-1 is fast, then slower, then it stops. That is what the trials show happening to almost everyone, and it is not a sign you have done something wrong.
The short version
The situation
It was working, and now the scales have barely moved for weeks.
The short answer
This is the normal shape of the curve. In the trials, weight comes off quickly at first, then slows, then flattens out somewhere in the second year. Almost everybody gets there.
The catch
Nobody tells you in advance, so it lands as personal failure rather than expected physiology. Then people start looking for something to add, which is exactly the moment the grey market is waiting for.
This is a reference, not medical advice. Anything about your own treatment is a conversation with whoever prescribes for you.
01The shape of the curve
Look at the weight-loss graph from any of the big trials and it is the same shape: steep at first, then bending, then almost flat. The published figures people quote, the double-digit percentages, are the total at the end of that curve, not a monthly rate that continues indefinitely.
Trials run to 72 weeks precisely because that is roughly where the curve flattens. If loss continued at the early rate, they would have run them longer.
Two things happen at once. The drug's appetite effect is roughly constant, but a smaller body needs less energy to run, so the gap between what you eat and what you burn closes. And the body defends against weight loss through hormonal and metabolic adjustments that have nothing to do with willpower.
A plateau is your body arriving at a new equilibrium, not the drug failing.
02What a plateau is not
- Not tolerance. The drug has not stopped working. It is still suppressing appetite, which is why weight is stable rather than climbing back.
- Not a sign you need something added. This is the point at which people start reading about stacking peptides, and it is worth being blunt: none of the compounds sold for this have human evidence of doing anything, and adding one to a licensed medicine is a decision nobody can advise you on because nobody has studied it.
- Not necessarily the end of dose increases. If you are not at the maximum licensed dose, there may be room, and that is a prescriber's decision rather than yours.
- Not failure. Maintaining a substantial weight loss is a clinical outcome in its own right, and holding it is genuinely harder than losing it.
03What the scale is not telling you
Weight is one number and a noisy one. Fluid shifts, constipation, and the time of day move it by more than a week of real change.
More usefully, evidence reported in June 2026 using genetic methods indicated GLP-1 drugs reduce fat mass considerably more than lean mass. If body composition is shifting while weight holds steady, the scale will show you nothing at all.
Other things that are actually the point: blood pressure, HbA1c if you have diabetes, how you sleep, what you can do without getting out of breath. Your practice measures several of these anyway.
04What is reasonable to discuss
Not things to do. Things to raise with the person prescribing for you.
- Whether there is room in the dose. Licensed maximums exist and you may not be at yours.
- Whether the plateau is the goal. If you have reached a weight that improves your health markers, the plan may reasonably shift from losing to holding.
- Whether something else has changed. New medication, a thyroid problem, or a change in circumstances can all show up as a stall.
- Resistance training. Clinical reviews consistently emphasise it alongside these drugs, for reasons covered in the muscle guide.
05Questions worth asking
Take these to your GP, practice nurse, pharmacist or specialist team. The answers are specific to you in a way nothing on this page can be.
- Am I at the maximum licensed dose, and is there room to increase?
- Given where I am now, is the goal still losing or is it holding?
- Have my other health markers improved even though the weight has stalled?
- Is anything else I am taking likely to be contributing?
06Common questions
Why has my weight loss stopped on Mounjaro or Wegovy?
Because that is the shape of the curve in every trial of these drugs: fast, then slower, then flat. A smaller body needs less energy, and the body defends against weight loss hormonally. It is expected physiology, not the drug failing.
Does the body build up tolerance to GLP-1 drugs?
Not in the way people mean. The appetite effect persists, which is why weight generally holds steady at a plateau rather than climbing straight back. What changes is the gap between energy in and energy out as body size falls.
Should I add something to break through a plateau?
Not an unlicensed compound. Nothing sold for this has human evidence of working, nobody has studied combining them with a licensed medicine, and your prescriber cannot advise on something with no data. Discuss the licensed options with them instead.
How long before weight loss plateaus?
It varies a great deal between individuals. The trial curves flatten out broadly in the second year, with most of the loss happening well before that. Yours will not follow the average exactly.
07Sources
- STEP trial programmePubMed
- SURMOUNT trial programmePubMed
- Genetic evidence on fat versus lean mass2026
- Obesity guidanceNICE
- Peptide stacks explainerOn this site
Told when guidance changes
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