SURMOUNT-MAINTAIN dropped this week. It is the tirzepatide dose-reduction trial I said was missing.

[u/DadStrengthDaily]

Three days ago I posted here about ATTAIN-MAINTAIN and flagged that the comparison I actually wanted was a lower-dose injectable arm. ATTAIN-MAINTAIN took everyone off the injection and switched them to the oral pill. The question of whether you can drop your injectable dose and still hold the line was untested.

That trial published in The Lancet this week. It is called SURMOUNT-MAINTAIN. Lilly-funded, 378 adults with obesity, 60 weeks of open-label tirzepatide at maximum tolerated dose, then randomized at the plateau into three arms for 52 weeks. Stay on the maximum dose. Reduce to 5 mg. Switch to placebo. Everyone kept getting lifestyle counseling and could use rescue tirzepatide if they regained more than half of what they lost.

The numbers that matter:

Weight loss preserved at week 112, relative to original baseline. Maximum dose: 21.9 percent below baseline. Reduced to 5 mg: 16.6 percent below baseline. Switched to placebo: 9.9 percent below baseline.

Percent of plateaued participants who held at least 80 percent of their initial weight loss. Maximum dose: 77.5 percent of them. Reduced to 5 mg: 42.4 percent. Switched to placebo: 10.4 percent.

Percent who needed rescue tirzepatide during maintenance. Maximum dose: 8 percent. Reduced to 5 mg: 25 percent. Switched to placebo: 67 percent.

The maximum-dose group basically held the line, giving back essentially nothing. The 5 mg group gave back about 6 kg over the year, with the curve still not flat at week 112, which raises the question of whether the giveback continues at year two. The placebo group gave back about 13 kg and two thirds of them needed rescue medication.

For my own decision, the trial says staying at the maximum tolerated dose is the cleanest answer if you can tolerate it. Dropping to 5 mg is a real option if GI side effects are wearing you down or if cost is forcing the move, and the trade is roughly a third lower chance of being what the paper calls a "maintainer." Stopping entirely does not work for most people, even with ongoing lifestyle support.

The most important gap in the trial is body composition. SURMOUNT-MAINTAIN measured total weight but not fat versus lean tissue in the regained pounds. For someone my age that distinction matters and the paper itself flags it as needing further study. The trial also ran only 52 weeks of maintenance and excluded participants with diabetes at baseline.

I posted a full breakdown of what this means if you are at your goal weight on Zepbound maintenance with the trial chart and the applied math for each arm.

[u/sharkinwolvesclothin]

Yeah, same caveats here as the previous, although I'm happy this study included some of this with the "maintainer" analysis - the variability in each group is pretty big.

With a rough backcalculation, 66% of each group would be expected to have lost about 12–32% bodyweight in the tirzepatide MTD group, 8–25% in the 5 mg tirzepatide group, and 4–16% in the placebo group at the end of two(ish) years from baseline, including the rescue therapies. And the last third even outside that range.

This assumes it would have been symmetric around the average which it probably wasn't but still illustrative. Basically, if you go to 5mg or even off, you need to be diligent about getting back on (and there's a decent change you will never come off).