GLP-1 weight-loss timeline: what to expect month by month

GLP-1 medicines work gradually. Doses start low and rise in steps, so your body can adjust, and weight loss builds over months. Knowing the usual rhythm helps you stay patient in the early weeks, and spot when something needs a conversation with your clinician.

Weeks 1–4: getting used to it

You'll start on the lowest dose. For tirzepatide that's typically 2.5 mg a week; for semaglutide, 0.25 mg. This starting dose is mainly about tolerance, not maximum effect. Many people notice their appetite quiets within the first days or weeks, and portions feel smaller.

This is also when side effects like nausea, fullness and constipation are most likely. Eating slowly, stopping when you're satisfied, avoiding large greasy meals and drinking plenty of water help.

Months 2–4: stepping up

Your clinician will usually raise the dose every four weeks or so, based on how you feel. Side effects can flare for a few days after each increase, then settle. Weight loss tends to become more visible in this stretch.

Months 4–12: the steady middle

Most of the weight loss in the big trials happened over the first year. In SURMOUNT-1, weight loss with brand-name tirzepatide continued for about 60 weeks before leveling off. In STEP 1, semaglutide's effect leveled off around week 60 as well.

This is the phase where habits do a lot of the work: protein at every meal, strength training two or three times a week, and sleep. These protect muscle and make the results easier to keep.

After a year: maintenance

Obesity is a long-term condition, and stopping medication usually means some weight returns. In the STEP 1 extension, people regained about two-thirds of the weight they had lost within a year of stopping semaglutide. In SURMOUNT-4, people who switched to placebo after 36 weeks regained a significant share, while those who continued tirzepatide kept losing.

That doesn't mean everyone needs medication forever. It means maintenance deserves a plan: your clinician may keep you on a dose, lower it, or taper slowly while you lean harder on habits.