Weight loss in your first week on Wegovy: what really happens

Step 1, your first injection: what the starting dose is actually for

Wegovy (semaglutide) is a GLP-1 receptor agonist. It works by mimicking a gut hormone that signals fullness, slows how quickly the stomach empties, and reduces appetite signals in the brain. The full Wegovy treatment pathway is a staged escalation: 0.25mg, then 0.5mg, then 1mg, then 1.7mg, and finally 2.4mg as the standard maintenance dose, with roughly four weeks between each step.

Week one sits at 0.25mg. At that level, most people notice only a mild reduction in hunger, if anything at all. That's intentional. The dose is calibrated to reduce the likelihood of nausea and digestive discomfort rather than to produce maximum appetite suppression. Think of it as your system finding its footing before the real work begins.

For many people, storing the pen in the fridge door becomes the first ritual, a small, steady reminder that this is a long-term commitment, not a quick intervention. The NHS overview of semaglutide confirms this staged approach and describes what to expect at each phase of treatment.

Step 2, what the scale does (and why it's misleading this early)

If you do see the number drop in week one, it's most likely fluid. Eating less, particularly fewer refined carbohydrates, causes the body to release stored glycogen, which carries water with it. That early shift on the scale is real weight, but it isn't the metabolic fat loss that Wegovy is designed to support over time.

Equally, some people see no change at all, or even a small increase, in the first seven days. This is entirely normal and carries no information about how well Wegovy will work for you long-term. The clinical trial data that supported Wegovy's approval showed an average weight reduction of around 15% over 68 weeks at the 2.4mg maintenance dose, a figure published in the STEP 1 trial in the New England Journal of Medicine. Week one is not a meaningful sample of that trajectory, and if you want to understand what that longer journey typically looks like, the wegovy resultater page brings together the kind of real-world outcomes that give a more grounded sense of what to expect.

If you're curious about what longer follow-up actually looks like, the timeline of how long Wegovy takes to work covers the typical arc from first injection to sustained results.

Step 3, side effects in the first week: what's common, what passes, what to watch for

The first week is when GI symptoms are most likely to appear. Nausea is the most reported, followed by loose stools, constipation, indigestion and a reduced desire to eat anything at all. For most people these are mild to moderate and settle within a few days. They tend to return, briefly, after each dose increase, so understanding this pattern early helps set realistic expectations for the months ahead.

Staying hydrated matters. If vomiting or diarrhoea is persistent enough to affect fluid intake, that's worth flagging to your prescriber promptly. Separately, the MHRA issued updated guidance in January 2026 on GLP-1 medicines and acute pancreatitis: severe, persistent stomach pain that radiates toward the back is a symptom that warrants urgent medical attention, not a wait-and-see approach. You can report any suspected side effects via the MHRA Yellow Card scheme.

On the question of what's normal versus what needs attention, our FAQs section covers the most common first-week questions our prescribers hear. And if you're looking at what results people typically see in the first few weeks, that page gives a fuller picture of the early trajectory.

What to carry into week two and beyond

Week one ends and little may have visibly changed. That's fine. The dose titration schedule means that meaningful appetite reduction typically builds from weeks four to eight onward, as the dose steps up. People who track their experience (appetite cues, energy levels, how portions feel) often find the early weeks more informative than the scale alone.

If week two brings continued low appetite suppression and you're wondering whether anything is working, that specific concern has its own answer. The short version: patience at this stage is clinically appropriate, not a sign of treatment failure.

Wegovy is a prescription-only medicine, and suitability depends on a full clinical assessment, BMI, weight-related health conditions, medical history and current medicines all factor in. A prescriber, not a checklist, makes that judgement. If you're considering whether private treatment is the right path, the free consultation at nume is reviewed the same day by a GPhC-registered prescriber, a real clinician, not software. There's no subscription, no auto-renewal and no hidden fees. If you'd like a broader sense of the weight-loss treatments available, that page covers the landscape. And for context on how private treatment is priced, the Wegovy cost and access page gives an honest breakdown.