What to do when the scale has not moved in three weeks
Check you are measuring weight, not water. Three flat weeks is almost never a metabolism problem. Body weight swings a couple of kilos inside a week on salt, carbohydrate, sleep and where you are in a cycle, so a single reading is a hydration measurement with a number on it. Weigh daily, first thing, and act only on the weekly average.
First, check you are measuring weight and not water
Body weight swings two to three kilos inside a single week on salt, carbohydrate, sleep and, for anybody who has a cycle, where in it you are. One weigh-in is a hydration reading with a number on it. A trend across weeks is the only version of this worth acting on.
Weigh daily, first thing, after the toilet, before food, and look only at the weekly average. Daily weighing sounds like the neurotic option and is the opposite: it gives you enough numbers that no single one can upset you. Weighing once a week hands one arbitrary morning total authority over your mood.
Three weeks flat is the right threshold
Two weeks is inside the noise for most people. Four weeks is long enough that you have lost a fortnight you did not need to lose. Three weeks of a flat weekly average, with the same measurement conditions each morning, is the point at which something has actually stopped.
Then check the intake, honestly
The most-replicated finding in this entire field is that people under-report what they eat, and the amount is not small. Weekends are where it hides: five tight days and two loose ones average out to maintenance, and the week feels like a deficit throughout.
The specific leaks, in the order they show up: oil in cooking, which is easily 200 calories nobody logs; drinks with calories in them; bites while cooking; and portions estimated by eye after the first fortnight of weighing. None of these is a discipline failure. They are measurement failures, and they respond to measurement rather than to trying harder.
Maintenance moves, and yours has
Eat less for a while and you move less without deciding to. You fidget less, walk slower, take the lift. It is real, it is measurable, and it is why a deficit that worked in week one does nothing in week six. Your maintenance is not the number an equation gave you in January; it is what your body is doing now, at this weight, with this much food and this much sleep.
What to change, in order
One thing at a time, and give it a fortnight.
First: add 2,000 steps a day. It is the cheapest 100 kcal in existence and it does not make you hungrier the way an extra cardio session does.
Second: hold protein and take 20 g of fat out. Protein is what protects muscle and appetite; fat is the easiest place to find calories without touching either.
Third, and only third: cut calories by another 150. Cutting first is the common move and it is the one that makes the next plateau arrive sooner, because it lowers the ceiling you have left to work with. If you have worked through that order and the weekly average still has not moved, coaching is somebody reading your numbers with you every week.
The case for a fortnight at maintenance
If you have been in a deficit for more than about twelve weeks, the answer to a plateau is sometimes to stop dieting for two weeks rather than to diet harder. Eat at maintenance, keep training, keep the protein up. Appetite, training output and mood usually recover, and the deficit works again afterwards. This is difficult to make yourself do and it is often the fastest route through.
And the thing that is not the scale
If your lifts are going up and your waist measurement is going down while the scale sits still, nothing is wrong. That is recomposition and it is the outcome most people actually wanted when they said they wanted to lose weight.
Take a waist measurement at the navel, once a week, same morning as the weigh-in. It is the single most useful number nobody tracks, and it moves in weeks where the scale does not.
When it is not a plateau at all
A new training programme, a big increase in training volume, creatine, a heavy salt day, or the week before a period will all hold water in a way that masks real fat loss for a week or three. If several of those changed at once, the flat line may be a measurement artefact sitting on top of genuine progress.
Common questions
Why has my weight not changed in three weeks?
Usually one of three things: you are reading water rather than fat, intake has drifted upward without being logged, or your maintenance has fallen because you move less in a deficit. Check them in that order before cutting calories again.
Should I cut calories when I hit a plateau?
Not first. Add 2,000 steps a day, hold that for a fortnight, then remove about 20 g of fat while keeping protein the same. Cutting calories is the third move, not the first, because it lowers the room you have left.
How often should I weigh myself?
Daily, first thing, after the toilet and before food, and then only look at the weekly average. Daily numbers give you enough data that no single morning can mislead you.
Can I be losing fat if the scale is not moving?
Yes. If your lifts are going up and your waist is going down while weight sits still, that is recomposition. Take a weekly waist measurement at the navel; it moves in weeks the scale does not.
How long should a diet break be?
About two weeks at maintenance, with protein and training held steady. It is worth considering after roughly twelve weeks of continuous deficit, particularly if appetite and training output have both fallen off.