When Does Wegovy Start to Work — and What Should You Notice First?

Week one: you've just injected your first dose, here's what's actually happening

Picture the scene: your Wegovy pen has come out of the fridge, you've done your first injection into your abdomen, and now you're wondering how long before anything shifts. The 0.25mg starting dose is low by design. Semaglutide begins binding to GLP-1 receptors in the gut and brain almost straight away, slowing how quickly your stomach empties and beginning to damp down the appetite signals that drive overeating. What you're unlikely to feel yet is a dramatic drop in hunger, but many people notice that meals feel slightly more filling, or that they stop eating a little sooner than usual. That's the medicine doing its early work. Nausea is the most commonly reported early experience, particularly in the first few days after an injection. It tends to be mild and settles within a day or two for most people. If you want a clearer picture of when Wegovy works and what that actually looks like in practice, it helps to read up before your first dose. The NHS medicines page for semaglutide has a practical rundown of what to watch for in the early weeks.

Weight on the scales at day seven? Probably not much different. That's fine. This phase is about your body adjusting, not transforming.

Weeks four to twelve: appetite suppression takes hold as the dose climbs

By the end of month one your prescriber will typically increase the dose to 0.5mg, then to 1.0mg around week eight or nine. This is where most people start to report a more noticeable shift in appetite, spontaneously eating less, losing interest in snacking, feeling satisfied much earlier in a meal. For many, this is also when the scales begin to move more consistently. It's worth keeping in mind that the degree of change varies considerably from person to person. Physiology, baseline weight, diet quality and how active someone is all play a role. Some people see a clear drop in body weight through this window; others find the change is subtler until a higher dose is reached. If you're curious about the broader question of when weight loss on Wegovy actually starts, the short answer is: often during this titration phase, but the pace is individual. Many people also find it useful to understand when Wegovy starts working at each stage of the dose schedule, so they know what to expect as the titration progresses. Understanding the likely timeline before you begin can help you set realistic expectations, our guide on the right time to start Wegovy covers the practical preparation side.

Months three to six: reaching maintenance dose and the steepest weight-loss phase

The standard maintenance dose for Wegovy has been 2.4mg weekly, reached after around four to five months of titration. This is where the clinical trial data becomes most relevant. The STEP 1 trial (a 68-week study whose results were published in the New England Journal of Medicine) recorded an average body-weight reduction of around 15% among participants taking semaglutide 2.4mg alongside lifestyle changes. That average sits across a wide range of individual outcomes. Some people lose considerably more; others less. The most rapid period of loss in the trial was typically between months three and twelve, once participants were established on their maintenance dose. From a practical standpoint, this is also the point at which lifestyle factors matter most. Wegovy reduces appetite; it doesn't override energy balance entirely. Protein intake, movement and sleep all influence how well the medicine's effect translates into sustained fat loss. If you're weighing up whether Wegovy is right for you alongside other options, you can explore the treatment approaches we offer to get a fuller picture.

Beyond six months: what sustains (and what slows) progress

Weight loss tends to plateau as the body adapts, usually between months nine and eighteen for most people on 2.4mg. This is normal physiology, not a sign the medicine has stopped working. For some patients, the MHRA-approved 7.2mg dose (a higher maintenance option approved in early 2026) may be appropriate; that's a clinical conversation, not something to adjust independently. If you're considering private treatment and want to understand what the process involves, including cost, Wegovy cost in the UK is worth reading before you start. On the question of when semaglutide starts to work in the longer term: the trial evidence is consistent that the medicine continues to maintain loss rather than just achieve it, which is why ongoing clinical oversight matters. Side effects generally ease after the first few weeks at any given dose, though some people experience them again briefly after each increase. If you're still deciding whether to go ahead, our Wegovy overview covers eligibility, the dose schedule and what the consultation process looks like. Treatment at nume is assessed personally by a GPhC-registered prescriber, not processed by software, your consultation goes to a real clinician the same day. If semaglutide sounds right for you, start your free consultation and let our clinical team give you a proper answer based on your full picture.