How Much Weight Can You Lose on a GLP-1?

If you're weighing a GLP-1 medication, the first question is usually the most practical one: how much weight can you actually expect to lose? The honest answer is that results vary a lot by person, but clinical trials give us useful averages to set realistic expectations.

What the clinical trials show

GLP-1 and dual-agonist medications have been studied in large trials, and two results are widely cited as benchmarks.

• Semaglutide (Wegovy) produced roughly a 15% average reduction in body weight over about 68 weeks in the STEP 1 trial.
• Tirzepatide (Zepbound) produced roughly a 21% average reduction over about 72 weeks in the SURMOUNT-1 trial.

These are averages across many participants who also received lifestyle support. Some people lost noticeably more, and some lost less. The numbers describe a group, not a guarantee for any single individual.

A quick way to picture it

To translate percentages into real numbers, apply them to a starting weight:

• At 15%, a 220 lb starting weight is about a 33 lb reduction on average.
• At 21%, that same 220 lb starting weight is about a 46 lb reduction on average.

Again, treat these as rough midpoints. Your body, dose, and how long you stay on treatment all move the number.

What about Ozempic and Mounjaro?

This is a common point of confusion. Ozempic and Mounjaro are approved for type 2 diabetes, not weight loss, and are frequently used off-label for weight management.

• Ozempic contains semaglutide, the same active ingredient as Wegovy.
• Mounjaro contains tirzepatide, the same active ingredient as Zepbound.

Because the active ingredients overlap, people often ask how much weight they can lose "on Ozempic." A reasonable expectation is in the same neighborhood as the semaglutide trials, though the diabetes versions were studied on different endpoints and dosing schedules. If you're deciding between brands, our Ozempic vs Wegovy comparison breaks down how they differ in approval and use.

Factors that shape your personal result

Two people on the same medication can end up with very different outcomes. The biggest drivers include:

1. Dose and titration. Most of these medications are gradually increased over weeks or months. People who reach and tolerate a higher maintenance dose often see larger changes.
2. Duration. The trial averages reflect roughly 15 to 18 months of treatment. Results at 3 months are typically much smaller than the headline figures.
3. Consistency. Missed doses, supply interruptions, and stopping and restarting all affect the trajectory.
4. Lifestyle support. Trial participants received nutrition and activity guidance alongside the medication. The drug reduces appetite; it doesn't replace overall habits.
5. Individual biology. Age, starting weight, metabolism, and other health conditions all play a role.

Because tirzepatide-based options showed a higher average in trials, some people specifically compare it against semaglutide. Our Zepbound vs Wegovy comparison walks through the differences in more detail.

How quickly does weight come off?

Weight loss on these medications is usually gradual, not sudden. A typical pattern looks like:

• Early weeks: modest changes as the dose is still low during titration.
• Middle months: the steepest part of the curve for many people as the dose increases.
• Later months: the pace often slows and eventually plateaus near a new stable weight.

A plateau is normal and expected. It reflects your body settling at a new set point rather than the medication "stopping working."

Setting realistic expectations

A few grounding points as you plan:

• The averages above assume you stay on treatment for well over a year.
• Results are not linear, and comparing your week 6 to someone else's week 60 is misleading.
• Cost and access influence how consistently people can stay on a medication, which in turn affects results. Brand cash prices run about $1,000 per month, while manufacturer savings programs, telehealth, and compounded options can be lower. You can estimate your own out-of-pocket range with our cost calculator.
• Not sure which option fits your goals and budget? Our find my GLP-1 tool can help narrow the field.

The bottom line

On average, semaglutide-based treatment is associated with about a 15% body-weight reduction and tirzepatide-based treatment with about 21%, both measured over roughly a year and a half in clinical trials. Your own result could land above or below those figures depending on dose, duration, consistency, and your individual biology.

This is general information, not medical advice — talk to a licensed clinician before starting or changing any medication. A clinician can help you set a realistic target and choose the option that fits your health and goals.