Because that is the shape weight loss has. In STEP-1 the average participant stopped losing weight at around week 60, having lost about 15%. The curve flattens. It is in the published data and it happens to almost everyone.
That does not make every stall the same, and which one you are in changes what is worth doing.
Start with the arithmetic
A smaller body needs less energy. Someone who has lost 15 kg needs meaningfully fewer calories to maintain their weight than they did at the start, so the same intake that produced a deficit six months ago may now produce none.
This is not the medication failing and it is not a metabolic malfunction. It is the ordinary consequence of being smaller.
The four kinds of stall
Too early to call. If you are in the first eight weeks, a few flat weeks tells you very little. Dose is usually still escalating, and the early period carries a lot of water movement in both directions. Keep going.
The expected plateau. If you have lost 12% or more of your starting weight, you are where the trials landed. This is the end of the curve rather than a stall to be broken, and the goal shifts from losing more to holding what you have — with as much of it as possible being fat rather than muscle.
Flat with the levers in place. Protein in range, training happening, weight not moving. This is the interesting one: body composition can keep improving while total weight does not move at all. The scale reports one number and cannot see the difference. If you have access to a scan or a smart scale, two readings will show you what the scale is hiding.
Flat with something to work with. Protein below range, or no resistance training, or both. Neither will necessarily restart the scale — but both change what a flat scale is made of, and a plateau where you are holding muscle is a completely different position from one where you are not.
Two things that are not what you think
Scale noise. Weight varies by a kilogram or more day to day from water, food volume and hormonal cycle. Three weeks of flat readings taken at different times of day may not be a plateau at all. Weigh under the same conditions and look at the trend, not the number.
Intake drift. Appetite suppression eases as the body adapts, and portions creep back without any decision being made. This is extremely common and not a character failing. Counting for three days once will tell you whether it has happened.
The response that makes it worse
Eating less again.
It is the obvious move and it is the wrong one. Cutting further while the scale is already flat is the pattern most associated with losing lean tissue, and it turns a plateau into an actual problem. It also tends to be unsustainable, which produces a cycle rather than a solution.
The same applies to increasing your dose to break through it. That is a clinical decision with clinical trade-offs and it belongs to the person who prescribes it, not to a frustrating month on the scale.
What is actually worth doing
- Confirm it is real. Same conditions, same time of day, three or four weeks of data.
- Check protein against your target. It is the input most likely to have slipped.
- Make sure resistance training is happening. Two sessions a week is the whole ask.
- Change what you are measuring. If weight has stopped and the levers are in place, the scale is now the least informative thing you own. Waist measurement, how clothes fit, and strength in the gym all carry information it does not.
- Talk to your prescriber if it persists and you are well short of where you expected to be.
The muscle check will tell you which of your inputs is furthest out of range, which is the useful question during a plateau — because it is the one where the answer changes something.