Why semaglutide can seem to stop working — and what the evidence says

What the STEP trial data actually show about long-term results

The STEP 1 trial followed adults with obesity over 68 weeks at the 2.4mg weekly dose. Average weight reduction reached roughly 15% of body weight, with the steepest losses in the first six months. After that, the curve flattened. This is not a quirk of semaglutide: it is a feature of how the body defends its weight over time.

When fat mass falls, the body lowers its resting energy expenditure and adjusts circulating appetite hormones to resist further loss. Leptin drops, ghrelin rises, and the metabolic brake tightens. If you want a fuller picture of how the active ingredient works, our semaglutide page explains the drug's pharmacology and what the evidence says about its use (you can read more about that mechanism on our semaglutide mechanism page) but the drug is now working against a stronger headwind. The plateau you see is your physiology, not the medicine losing potency.

Understanding this distinction matters because the practical response is different. If the medicine itself had stopped working, stopping it would make no difference to your trajectory. In reality, Wegovy's long-term weight-maintenance data show that most people regain weight when semaglutide is discontinued, which confirms it is still active, the body's setpoint has simply found a new balance with the drug on board.

Factors that can make a plateau arrive earlier than expected

Not every plateau is purely physiological. Several practical factors shorten the window of active weight loss, and a prescriber reviewing your case will usually work through these before concluding the medicine has been maximised.

Dose level matters. Semaglutide is titrated gradually, and some people reach their maintenance dose before the full appetite-suppression effect has built. If you are still on a lower rung of the titration schedule, there may be meaningful response left at a higher dose, that is a clinical assessment, not a self-adjustment.

Injection technique is another overlooked variable. Injecting into scar tissue from repeated use of the same site reduces absorption. A quick check takes under a minute: look at your last three injection sites and ask whether you have been rotating consistently between abdomen, thigh and upper arm. If not, that alone can restore consistency. Storage temperature is similar, a pen that has been left out for longer than the patient information leaflet permits may deliver less active medicine than expected.

Lifestyle drift also plays a role. The appetite suppression that semaglutide provides can mask a gradual creep in calorie intake as weight loss motivation fades. This is not a willpower failure; it is a well-documented behavioural pattern that clinical programmes account for. The NHS patient information on semaglutide notes that the medicine works alongside a reduced-calorie diet and increased activity, not instead of them.

When a plateau might signal something else

Occasionally a plateau reflects a medical variable worth investigating. Thyroid function, insulin resistance, certain medications and significant life stressors all influence the rate at which weight changes. None of these make semaglutide ineffective in itself, but they can shift the balance enough to stall progress.

If you have been on a stable maintenance dose for three months or more with no measurable change, a review with your prescriber is the right step. At nume, our clinical team reviews repeat orders before every dispatch, it is not a tick-box; it is an opportunity to catch exactly this kind of situation. A prescriber may consider whether the current dose remains appropriate, whether the titration schedule should continue, or whether any other clinical factor needs addressing.

For a broader look at what to do practically when progress stalls, our page on managing a semaglutide plateau covers the options in detail. People sometimes ask whether Wegovy stops working after a while, and that page addresses the question directly, including what the evidence says about long-term response. There is also useful context in NICE's appraisal of semaglutide for weight management, TA875, which notes that continuing treatment should be reviewed if less than 5% weight loss is achieved after six months on the maintenance dose, a threshold that gives a concrete benchmark for these conversations.

If you are weighing up whether semaglutide is still the right treatment for your situation, starting a free consultation is the most direct route to a personalised answer. Many people also find it helpful to read about when Wegovy starts working, particularly if they are early in treatment and trying to set realistic expectations. Our treatment consultation page walks through how that works.