Semaglutide weight loss results: what clinical trials actually found

Step 1: the slow build through titration (weeks 1–16)

Semaglutide does not arrive at full therapeutic strength on day one. The licensed schedule starts at 0.25mg weekly, stepping up roughly every four weeks through 0.5mg, 1.0mg and 1.7mg before reaching the 2.4mg maintenance dose. The early weeks are primarily about your body adjusting: appetite changes begin to register, but the scale is unlikely to move dramatically. Most people find noticeable progress arrives somewhere between weeks 8 and 16, once the dose has climbed past the halfway point of titration.

If you are curious about the earliest weeks specifically, our one-week results page sets realistic expectations for that initial period, and the four-week picture covers what the first full month of treatment typically looks like. Titration pace and whether you move to a higher dose are clinical decisions; your prescriber will review your response before any step up.

Step 2: the evidence base behind the 15% figure

The 15% average weight reduction from STEP 1 is a population mean across 1,961 adults with obesity who had no type 2 diabetes. Individual results spread around that average: some participants lost considerably more, others less. Roughly one third lost more than 20% of body weight. The NHS medicines page for semaglutide acknowledges this range and explains that results depend on consistent use alongside a calorie-reduced diet and increased physical activity.

The MHRA approved a dedicated single-dose 7.2mg pen in April 2026. In its supporting trials, participants reached around 20.7% average weight loss over 72 weeks, a figure that narrows the gap with the highest tirzepatide dose. It is worth noting that 7.2mg is the maximum and is reached after a full titration sequence; it is not a starting point. For a broader look at how Wegovy results compare with what the clinical record shows across different timeframes, the Wegovy weight loss results page covers that evidence in more depth.

Step 3: the factors that move results up or down

Researchers and clinicians are clear that semaglutide works as part of a package. The STEP 1 participants received dietary counselling alongside the injection; those in the placebo arm who received the same support still lost around 2.4% on average, which tells you something about the medicine's specific contribution. In practice, the people who see the strongest results tend to reach and sustain the maintenance dose, maintain adequate protein intake to preserve muscle mass, keep up some form of regular activity, and stay on treatment long enough for the medicine to work, typically at least six months before drawing conclusions.

Starting BMI, age, and whether any metabolic conditions are present all influence how the body responds. There is no reliable way to predict in advance exactly how much weight a specific individual will lose. That honest uncertainty is part of why treatment is clinician-led rather than a straightforward purchase.

What happens when semaglutide is stopped

The evidence on discontinuation is consistent and worth knowing before you start: weight tends to return, partially, after stopping. A follow-up study to STEP 1 found that one year after participants stopped semaglutide, around two thirds of the weight lost had been regained. This is not a failure of the medicine; it reflects the biology of appetite regulation, which returns towards its baseline once the drug is no longer present, and our page on how long semaglutide takes to clear the body explains the pharmacology behind that process.

This reality shapes how prescribers approach duration conversations, and why it matters to have ongoing clinical oversight rather than ordering a single pen and deciding for yourself. Our page on how long Wegovy takes to work addresses both the ramp-up and the longer arc of treatment. If you are thinking about whether semaglutide is the right fit (or how private treatment is priced) the Wegovy cost page lays out what a legitimate prescription service includes. When you feel ready to talk to someone clinical rather than read more articles, starting a free consultation is the next step. A named prescriber reads your answers the same day; no algorithm makes the call.