Plateaus happen on medication too. If you are taking a GLP-1 medication and the scale has flattened, nothing in this chapter will surprise a physician — but it may surprise you, because the marketing around these medications rarely mentions the shape of the curve.

What the trials actually show

The large approval trials give us the honest picture, because they followed thousands of people for well over a year and published the averages.

In the STEP 1 trial, adults taking weekly semaglutide lost an average of 14.9 percent of their body weight over 68 weeks, against 2.4 percent with placebo. In SURMOUNT-1, adults on the highest dose of weekly tirzepatide lost an average of 20.9 percent over 72 weeks, against 3.1 percent with placebo.

Average weight-change curves from the approval trials: semaglutide reaches about minus 14.9 percent by week 68 and flattens; tirzepatide at the highest dose reaches about minus 20.9 percent by week 72 and flattens; placebo stays near minus 2 to 3 percent. A dashed continuation marks the STEP 1 extension, in which about two-thirds of lost weight returned within a year of stopping treatment and lifestyle support. — The plateau is in the trial data: both average curves flatten — and in STEP 1’s extension, stopping returned about two-thirds of the lost weight within a year.

Now look past the headline numbers to the shape. In both trials, average weight fell steeply through the early months, then the curve bent and flattened as the trials went on. The plateau is in the trial data. People taking these medications exactly as designed, inside carefully run studies, still arrived — as a group average — at a level place late in each trial’s follow-up. If you are on treatment and the scale has settled, you may simply have reached the same part of the curve; when that happens varies widely from person to person, and the trials report group endpoints, not individual timetables.

Averages are averages: individual responses spread widely around them, which is one more reason a flat month on your scale cannot be interpreted without context.

What happens when treatment stops

One more trial result belongs in this chapter, because plateau frustration is a common reason people quit treatment. When STEP 1 participants stopped semaglutide and the structured lifestyle support that came with it, they regained about two-thirds of their lost weight within the following year, on average.

Where a plateau on treatment leads

So a flat trend on medication is a fork with three honest paths, and all of them run through your prescriber. It can mean you have reached this treatment's equilibrium for your body — and the conversation becomes about maintenance, goals, and whether the current result already serves your health. It can mean the regimen has room to work that it is not getting — the audit from Chapter 3, especially treatment exposure, feeds directly into that visit. Or it can mean the plan itself deserves a medical review. What it never means is that you should adjust doses, stretch intervals, or stop on your own.

If you want the broader context on how physician-supervised GLP-1 care works, WellForm's GLP-1 overview explains the treatment category; this book stays with the plateau itself.

Chapter summary

What to take away

In STEP 1, semaglutide averaged 14.9 percent loss over 68 weeks versus 2.4 percent with placebo; in SURMOUNT-1, the highest tirzepatide dose averaged 20.9 percent over 72 weeks versus 3.1 percent.
Both trial curves flatten. A plateau on treatment is part of the documented shape, not proof of failure.
After stopping semaglutide and lifestyle support in STEP 1's extension, participants regained about two-thirds of lost weight within a year, on average.
A plateau on medication is a conversation with your prescriber — never a reason to self-adjust or quietly quit.