How long semaglutide takes to work and how much weight people lose

How semaglutide works in the body

Semaglutide is a GLP-1 receptor agonist, the drug class the Wegovy label refers to when it says not to combine it with any other GLP-1 receptor agonist ^[1]. The label also states it slows how fast the stomach empties, which is why it can change how other pills are absorbed ^[1]. For a plain explanation of the hormone system involved, see how GLP-1 drugs work.

It is not a stimulant, and the label does not describe it as raising metabolism. Semaglutide as a molecule was first approved in the US in 2017 ^[1].

The timeline: when it starts working

No label sets a day when appetite changes. What the label does set is the dose path, because people do not start at the full dose:

• Wegovy injection: 0.25 mg weekly for weeks 1 to 4, 0.5 mg for weeks 5 to 8, 1 mg for weeks 9 to 12, 1.7 mg for weeks 13 to 16, then a maintenance dose from week 17 ^[1].
• Wegovy tablets: 1.5 mg daily for days 1 to 30, 4 mg for days 31 to 60, 9 mg for days 61 to 90, then 25 mg from day 91 ^[1].
• Ozempic (type 2 diabetes): 0.25 mg weekly for 4 weeks, then 0.5 mg, with increases after at least 4 weeks up to 2 mg ^[3].

Trial results were measured at the end of long studies, not week by week. STEP 1 reported results at 68 weeks ^[2]. Full dosing detail is on our semaglutide dosage page.

How much weight people lose on semaglutide

In STEP 1, adults with overweight or obesity on semaglutide 2.4 mg lost an average 14.9% of body weight at 68 weeks, vs 2.4% on placebo ^[2]. In the same trial, 86.4% lost at least 5%, 69.1% lost at least 10% and 50.5% lost at least 15%, compared with 31.5%, 12.0% and 4.9% on placebo ^[2].

In SURMOUNT-5, a head-to-head trial, people on semaglutide lost an average 13.7% at 72 weeks vs 20.2% on tirzepatide ^[4]. See Wegovy vs Zepbound for the full comparison.

Average weight change in semaglutide trials

Trial	Dose	Length	Semaglutide	Comparison
STEP 1 [2]	2.4 mg weekly	68 weeks	-14.9%	-2.4% placebo
OASIS 4 [5]	25 mg tablet daily	64 weeks	-13.6%	-2.4% placebo
SURMOUNT-5 [4]	Semaglutide vs tirzepatide	72 weeks	-13.7%	-20.2% tirzepatide

Why you might not be losing weight, or gaining

Not everyone responds the same. In STEP 1, about 1 in 7 people on semaglutide (13.6%) did not reach 5% weight loss ^[2]. Still on a low starter dose? You may not be at a maintenance dose yet, which on the Wegovy schedule is week 17 ^[1].

For adults on Wegovy who tolerate 2.4 mg for at least 4 weeks, the label allows a move to 7.2 mg weekly if more weight loss is clinically indicated ^[1]. That is a prescriber decision. The label does not address weight gain on semaglutide; if your weight is rising, bring your dose history and food and activity notes to your prescriber.

Do semaglutide pills work?

Wegovy tablets are FDA-approved for weight reduction in adults, and Novo Nordisk announced that approval on December 22, 2025 ^{[1] [5]}. In the OASIS 4 trial, adults on the 25 mg tablet lost an average 13.6% of body weight at 64 weeks vs 2.4% on placebo, counting everyone whether or not they stayed on treatment ^[5]. The label says its side effects were similar in type and frequency to the 2.4 mg injection ^[1]. Compare the two in Wegovy pill vs injection.

Ozempic's label covers type 2 diabetes, heart risk and kidney disease in diabetes; weight loss is not an approved use ^[3]. Rybelsus is another semaglutide medicine from Novo Nordisk ^[7]. We could not read its label for this update, so check that label for what it is approved to treat.

Does compounded semaglutide work?

No one can say from FDA data. Compounded semaglutide is not FDA-approved, and FDA does not review it for safety, effectiveness or quality ^[8]. The STEP 1 and SURMOUNT-5 results come from the branded drug. FDA also warns that some compounded products use semaglutide sodium or acetate salt forms, which are different active ingredients ^[8]. More in our compounded semaglutide guide.

How long it lasts and how long people stay on it

The label gives no clearance time in days. It does call semaglutide's half-life long, and for that reason tells people to stop at least 2 months before a planned pregnancy ^[1]. Wegovy is approved for long-term weight maintenance, and the label sets no end date ^[1]. When treatment stopped in the STEP 1 extension, people regained about two-thirds of the weight they had lost within a year ^[9].

Who can get it and what it costs

Wegovy is approved to reduce excess body weight and keep it off long term in adults and children 12 and older, and to lower the risk of major heart events in adults with heart disease and obesity or overweight ^[1]. A prescription is required. Wegovy pens cost $349 a month self-pay through NovoCare, checked October 17, 2026, with a $199 starter price for the first two fills of the lowest doses through December 31, 2026 ^[10]. See semaglutide cost for every channel and online semaglutide programs for prescribers.