The most common question in my inbox is not about side effects, or cost, or muscle. It is some version of when is this supposed to start working — usually sent around day nineteen, usually by someone who has already weighed themselves eleven times.
Why the first month is deliberately slow
Wegovy starts at 0.25 mg weekly. That dose was not chosen to produce weight loss; it was chosen so your gut can adapt to slower gastric emptying before the dose climbs. Every four weeks the dose steps up — 0.25, 0.5, 1.0, 1.7, then 2.4 mg — which means the earliest anyone reaches the top of the ladder is about week seventeen.
Judging the drug in month one is judging it below the range at which it was studied.
There is also a pharmacokinetic reason the timeline feels laggy. Semaglutide has a half-life of roughly a week. After any dose change, blood levels take four to five weeks to reach a new steady state. So the effect you feel in week four is the previous month’s dose finally arriving in full.
What actually happens, week by week
Week 1–2: the quiet
The first thing most people notice has nothing to do with weight. Meals end earlier than expected. A portion that was normal last month becomes uncomfortable. Some people describe losing interest in food between meals — the constant background negotiation going quiet.
Roughly a third of people feel some nausea in this window. It usually arrives a day or two after the injection and fades over the following few days.
Week 3–4: the flat spot
This is where people panic. The scale has often moved very little, water weight has done something unhelpful, and week four is the first dose increase — which frequently brings a fresh round of nausea just as motivation is lowest.
Almost every discontinuation I have seen that the patient later regretted happened in this window.
Week 5–12: the slope
Once the dose is at 0.5 mg and then 1.0 mg, the scale generally starts to behave. A commonly quoted average is roughly one to two pounds per week during active escalation, but the spread around that average is very wide, and body composition, starting weight and sex all move it.
Month 4–12: the long part
This is where most of the total weight loss actually occurs. In STEP 1, the curve was still descending at week 68 and had only begun to flatten toward the end.
Month 12–18: the plateau
Weight loss slows and then stops. This is normal, expected, and the point at which the conversation should change from losing to maintaining — a conversation almost nobody has scheduled in advance.
~1 week
Time to first noticeable appetite change for most people
4–5 weeks
Time for blood levels to stabilise after each dose increase
Semaglutide half-life ≈ 7 days
68 weeks
Length of the pivotal trial — the curve had not fully flattened by the end
STEP 1, NEJM 2021
The comparison that ruins people
Somebody in your life will lose twenty pounds in eight weeks and tell you about it.
Individual response to this drug class varies more than almost any medication I prescribe. Two people, same starting weight, same dose, same adherence, will separate by twenty pounds over a year and neither of them did anything wrong. A meaningful minority of people are what the literature politely calls non-responders, and that is a biological fact about them rather than a moral one.
The only useful comparison is with your own trajectory eight weeks ago. Everyone else’s month one is noise.
Which presupposes that you have some record of eight weeks ago. Weight once a week on the same morning, appetite noted in two words, dose and date — that is enough to reveal a trend that daily weighing buries inside water fluctuation. I ask people to keep it in Zenday or something like it specifically for this stretch, because in month two a graph does the reassuring far better than I can over the phone.
When slow is actually a problem
There is a difference between “slower than I hoped” and “nothing is happening.”
Worth raising with your clinician:
- No appetite change at all by the time you have completed a month at 1.0 mg
- Less than about 5 percent of body weight lost after roughly three months at a therapeutic dose
- Side effects severe enough that you are stuck below an effective dose indefinitely
- Weight loss that stalls completely and early, well before the usual plateau window
Any of those is a reason to look at technique, storage, adherence, or whether a different agent suits you better. None of them is a reason to double a dose on your own.
The reframe that helps
Twelve to eighteen months is not a long time to treat a chronic condition. It only feels long because we are culturally trained to measure weight loss in weeks, on television, with a countdown.
Nobody asks how quickly their blood pressure medication is working on day nineteen.