There are two different clocks
The drug starts working on your appetite almost immediately. It starts working on the scale considerably later. Conflating those two is why so many people conclude in week three that it is not doing anything.
The first four weeks
Most people notice some appetite change within the first week or two, sometimes after the very first injection. Smaller portions feel like enough, and the pull toward snacking softens.
Weight change in this window is usually modest, and that is by design. The 0.25 mg starting dose is not a therapeutic dose for weight. It exists to let your gut adapt before the doses that actually do the work.
Why every step is four weeks
With a half-life of about a week, it takes roughly four to five weeks for blood levels to stabilise after any dose change. Until then you are still on your way to the full effect of the dose you just moved to.
That is the pharmacological reason the schedule holds each dose for four weeks, and the reason climbing faster mostly buys you side effects rather than time.
When the scale usually moves visibly
For most people, weight change becomes clearly visible somewhere between weeks eight and twelve, which is around when they reach 1.0 mg. The steepest part of the curve typically comes after that, through the higher doses and the months following.
Maintenance at 2.4 mg is reached at week seventeen at the earliest, and plenty of people take longer or stop at a lower dose that suits them. Both are normal.
So what is the honest answer
How long it takes depends more on what dose you have reached than on how many weeks have elapsed. Two people at week twelve can be in completely different places if one has escalated on schedule and the other has held at 0.5 mg for tolerability.
Judge progress against where you are in the titration, not against the calendar.
If it genuinely seems to be doing nothing
Before concluding it is not working, work through this list.
- Are you on a therapeutic dose yet? Below 1.0 mg, limited effect is expected rather than surprising.
- Has the medication been stored correctly, and has it ever frozen? A frozen product is discarded, not thawed.
- Are you drawing the dose you think you are? This is the common failure mode with vials rather than pens, and it goes wrong by factors of ten.
- Is this a plateau rather than a non-response? A flattening curve after months of loss is expected.
- If you are three to four months in at a therapeutic dose and have lost under 5%, that is a reasonable point to talk to your prescriber about reassessing.
The oral tablet is a different case
Oral semaglutide is taken daily rather than weekly and absorbs poorly and inconsistently. It has to be taken on an empty stomach with no more than a small sip of plain water, waiting at least thirty minutes before eating, drinking or taking anything else.
Those instructions are not fussiness. Getting them wrong is the most common reason an oral dose does very little.
Sources
- Wegovy (semaglutide) injection, prescribing information. Novo Nordisk.
- Rybelsus (semaglutide) tablets, prescribing information. Novo Nordisk.
- Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021;384(11):989-1002.
- Friedrichsen M, et al. The effect of semaglutide 2.4 mg once weekly on energy intake, appetite, control of eating, and gastric emptying in adults with obesity. Diabetes Obes Metab. 2021;23(3):754-762.