Nobody lost weight on monthly dosing. Everyone in the study spent 21 weeks on weekly injections first, and the monthly part only tested whether they could hold on to what they had already lost.
On September 22, 2026, Viking Therapeutics released topline results from a maintenance study of VK2735, its injectable GLP-1/GIP drug.1 The headline travelling with it is that monthly dosing maintained up to 90% of weight loss, and every-other-week dosing up to 97%.
Those figures are real and they are percentages of a percentage. The column they come from is headed "Mean percentage of Week 21 weight loss maintained at Week 33", so 90% means nine tenths of a loss already achieved, not nine tenths of anything on the scale.1
One figure from the same tables did not travel with the headline. Placebo maintained 61%.
Figures as of October 12, 2026, taken from the two Viking Therapeutics releases cited below. This is a topline announcement, so the numbers may change when a full publication appears.
What did the study actually do?
Twenty-one weeks of weekly injections, then twelve weeks of something less frequent.
The trial, identified by the company as VK2735-102, enrolled approximately 180 adults with a BMI of 30 or above and otherwise healthy.1 It ran in two parts.
The induction phase gave everyone weekly subcutaneous VK2735 or placebo for 21 weeks, with doses titrated upward to final levels of 15.0, 17.5, 20.0 or 22.5 mg. Weight loss across the VK2735 cohorts came in around 16% to 19%, against roughly 0% on placebo, and the company describes the loss as progressive with no plateau.1
The maintenance phase then ran 12 weeks, from Week 21 to Week 33. Participants moved to every-other-week injections, sometimes called biweekly or every two weeks, or to monthly injections, or to placebo.1
Every person in every maintenance arm therefore arrived having already lost around a sixth to a fifth of their body weight, on weekly injections at high doses. Every maintenance figure below should be read against that starting point.
Does this show monthly dosing causes weight loss?
The study was not designed to measure that, and it did not. No arm began on monthly dosing.
The question a reader has when they see "once a month" is whether they could start on a monthly injection and lose weight. This study cannot answer that, because no arm did it. Monthly dosing began at Week 21 for people who were already down 16% to 19%.
Those are different claims with different evidence behind them:
- Losing weight on monthly dosing from the start. Untested here. No arm began monthly.
- Holding on to weight already lost, after a weekly run-in. This is what was tested, over 12 weeks.
A drug that holds a result in place and a drug that produces the result are not interchangeable, and a maintenance study is designed around the first.
What were the actual numbers?
Every maintenance figure below is expressed as the share of Week 21 loss still held at Week 33.
| Maintenance regimen | Weekly induction dose | Share of Week 21 loss maintained |
|---|---|---|
| Every other week, 10.0 mg | 17.5 mg | 97% |
| Every other week, 7.5 mg | 15.0 mg | 90% |
| Monthly, 17.5 mg | 17.5 mg | 90% |
| Monthly, 20.0 mg | 20.0 mg | 86% |
| Monthly, 22.5 mg | 22.5 mg | 85% |
| Monthly, 15.0 mg | 17.5 mg | 84% |
| Every other week, 5.0 mg | 17.5 mg | 83% |
| Monthly, 10.0 mg | 17.5 mg | 82% |
| Placebo | various | 61% |
All figures from the company release of September 22, 2026.1 The combined every-other-week group was 37 people, the combined monthly group 65 in the efficacy table, and placebo 27.1
Placebo held 61%. People who stopped the drug entirely still kept that much of what they had lost, across the same 12 weeks. So the gap between doing nothing and the best monthly regimen is 29 percentage points of retained loss, not 90. The company reports the comparisons as statistically significant, at p<0.0001 for the every-other-week group and p=0.0002 for the monthly group.1
That placebo figure is also a reminder of how short 12 weeks is. Weight regain after stopping these drugs is well documented over longer periods, and a three-month window catches the early part of a curve rather than where it settles.
What happened to people who stayed on weekly?
They carried on losing weight, and the maintenance framing leaves that out of the picture.
A separate exploratory cohort of 13 people continued on 17.5 mg weekly through the maintenance period. At Week 33 they showed "mean weight loss of 21.7% from baseline", against a 0.3% weight gain on placebo.1
Set that beside the induction figures of 16% to 19% at Week 21 and the shape becomes clear. Staying weekly carried on working. Every reduced-frequency arm gave something back.
So monthly dosing here produced a managed decline from a peak instead of a plateau at it. Whether that trade suits a given person is a real question, and a different one from what the headline percentage implies.
How does this compare with the maintenance trials that have published?
Two have, for semaglutide and tirzepatide, and both reported a different number from the one Viking reported.
The run-in-then-randomise design is not unusual. It is how the two published maintenance trials in this class were built, so VK2735-102 is following an established template.
| Trial | Lead-in | Weight lost in lead-in | Period after randomisation | On continued drug | On placebo |
|---|---|---|---|---|---|
| STEP 4, semaglutide, the Wegovy molecule3 | 20 weeks to 2.4 mg weekly | 10.6% | 48 weeks | −7.9% | +6.9% |
| SURMOUNT-4, tirzepatide, the Zepbound and Mounjaro molecule4 | 36 weeks at 10 or 15 mg weekly | 20.9% | 52 weeks | −5.5% | +14.0% |
| VK2735-1021 | 21 weeks to 15.0 to 22.5 mg weekly | 16% to 19% | 12 weeks | 82% to 97% of loss held | 61% of loss held |
Three differences stand out, and none of them is about which drug was used.
- The bottom row is in different units from the two above it. STEP 4's primary endpoint was "percent change in body weight from week 20 to week 68", and SURMOUNT-4 reported percent weight change from week 36 to week 88.34 Both are absolute changes on the scale, while Viking reported the share of earlier loss still held. The two cannot be set against each other without the underlying absolute numbers, and those were not published.
- Both published trials ran four times longer after randomisation. Forty-eight weeks and 52 weeks, against 12.
- In both, placebo did not hold at 61%. It climbed. People who switched to placebo in STEP 4 put on 6.9% of body weight over 48 weeks, against a 10.6% loss in the run-in.3 In SURMOUNT-4 they put on 14.0% over 52 weeks, against a 20.9% loss.4 A 12-week window catches the shallow start of that curve, and that is part of why 61% looks reassuring.
Continued dosing kept working in both trials. Semaglutide came in at −7.9% and tirzepatide at −5.5% from randomisation, the same direction as Viking's exploratory cohort that stayed on weekly and reached 21.7% from baseline.1
There is an authorship overlap worth recording. Louis Aronne is the first author of SURMOUNT-4 and is also the physician quoted in Viking's release, where he is disclosed as a paid consultant to the company.14
Is this a published study?
It is a company press release of topline results, with no publication behind it.
There is no peer-reviewed publication, no conference presentation and no posted results. The release does not give a ClinicalTrials.gov identifier for the study, naming it only as the VK2735-102 maintenance study.1 Our compound page's line that VK2735 has registered trials with none posting results still holds, because a topline announcement from a sponsor is not posted results.
The physician quoted in the release, Dr Louis Aronne, is described in the release's own footnote as "a paid consultant to Viking Therapeutics, Inc."1 The disclosure is there in the release, and it matters when the quote gets reused elsewhere as independent endorsement.
What do the company's own two releases disagree about?
They disagree about the schedule and about the status of the weight numbers.
When Viking announced enrolment was complete on January 8, 2026, it described the same trial differently in two ways.
The induction period was 19 weeks, not 21. The January release says participants receive "initial weekly subcutaneous doses of VK2735 or placebo for 19 weeks" and describes weight change "from Week 19 to the end of the study at Week 31".2 The September release describes 21 weeks of induction and a study ending at Week 33. The company does not explain the two-week shift, and a protocol change partway through a trial is an ordinary thing that is ordinarily disclosed.
The weight figures are exploratory endpoints. The January release lists the study objectives as evaluating "the safety, tolerability, and pharmacokinetic profile" of VK2735, and names body weight change from baseline and from Week 19 to Week 31 as exploratory endpoints.2
That reframes the readout. The percentages now circulating as the result of this study are, by the sponsor's own earlier description, exploratory endpoints from a trial whose stated objectives were safety, tolerability and pharmacokinetics. Exploratory endpoints are not nothing. They are also not what a trial was powered to answer, and they carry no multiplicity control, so they are normally reported as observations instead of findings.
What about the pill?
The oral arms were planned from the start and have not reported, so none of this covers the pill.
The January release describes maintenance regimens that include "daily oral dosing, weekly oral dosing, or placebo" alongside the injectable arms.2 The September topline reports only subcutaneous every-other-week and monthly results, and the company says it "plans to explore oral maintenance dosing regimens in an upcoming part 2 to the current study".1
Whether a tablet could hold weight loss in place is still an open question, and anything describing this readout as covering oral dosing is describing a study that has not reported.
How were the side effects?
Reported as unremarkable during maintenance, over 12 weeks.
On the side effects people ask about, the company describes gastrointestinal adverse events during maintenance, covering nausea, vomiting, diarrhoea and constipation, as not meaningfully different from placebo.1 Treatment-emergent adverse events ran 52% on placebo, 38% across the combined every-other-week group and 49% across the combined monthly group.
Discontinuations for adverse events during maintenance were one person in the combined every-other-week group, one in the 10 mg every-other-week arm and one in the combined monthly group. During induction, one subject discontinued for an adverse event.1
Both of those figures come with conditions. A maintenance phase inherits a population that already tolerated 21 weeks of weekly dosing, so anyone who could not take the drug had largely left before this phase began. And a 12-week window at reduced frequency is short for tolerability questions.
What does this change about buying it?
Nothing at all. VK2735 is approved nowhere, and there is no legal route to it outside a trial.
Our compound page already carries that, and the new results do not alter it. What they do change is the dose range in circulation: this study titrated to final weekly doses of 15.0 to 22.5 mg. That sits above the range the earlier Phase 2 work established and above what our own compound page currently lists.
A research-labelled vial carries no assurance that its contents match any dose in any of these tables, and nothing in a topline press release makes an unapproved compound safer to inject.
Two things this readout says nothing about. It reports no body composition data, so whether the weight held during maintenance was fat or lean tissue is unknown, and our guide to what happens after significant weight loss covers why that question matters. And it offers no comparison with retatrutide or any other compound in this class, because no head-to-head trial exists.
Common questions
Can you take VK2735 once a month?
In the maintenance study, monthly injections held 82% to 90% of weight already lost over a 12-week period, after 21 weeks of weekly injections first. Nobody in the study started on monthly dosing, so there is no evidence here about losing weight on a monthly schedule from the beginning.
How much weight did people lose on VK2735?
In the induction phase of this study, around 16% to 19% of body weight over 21 weeks of weekly injections at final doses of 15.0 to 22.5 mg, against roughly 0% on placebo. An exploratory cohort that stayed on 17.5 mg weekly reached 21.7% from baseline at Week 33.
What does "maintained 90% of weight loss" mean?
It means nine tenths of the weight lost by Week 21 was still off at Week 33. It does not mean 90% of body weight, and it is not an absolute weight change. The company reported maintenance as a percentage of Week 21 loss and did not publish an end-of-study absolute weight change for each maintenance arm.
How did placebo do in the maintenance phase?
Placebo maintained 61% of the Week 21 weight loss over the same 12 weeks. That is the comparator the headline percentages should be read against.
Is monthly dosing as good as weekly?
Not in this study. Every reduced-frequency arm gave back some of the Week 21 loss, while an exploratory cohort that continued weekly dosing kept losing and reached 21.7% from baseline at Week 33.
How does this compare with STEP 4 and SURMOUNT-4?
Those two are the published maintenance trials for semaglutide and tirzepatide, and both reported a different measure. STEP 4 gave percent change in body weight from week 20 to week 68, at −7.9% on continued semaglutide against +6.9% on placebo. SURMOUNT-4 gave −5.5% on continued tirzepatide against +14.0% on placebo from week 36 to week 88. Viking reported the share of earlier loss still held rather than an absolute change, so the numbers cannot be lined up directly. Both published trials also ran four times longer after randomisation, 48 and 52 weeks against 12.
Does weight come back if you stop?
In the two published maintenance trials it did. Switching to placebo in STEP 4 produced a 6.9% gain in body weight over 48 weeks, against a 10.6% loss in the run-in. In SURMOUNT-4 it produced a 14.0% gain over 52 weeks, against a 20.9% loss. In the VK2735 study, placebo held 61% of the Week 21 loss across 12 weeks. That is a much shorter window and an earlier part of the same curve.
Has this been published or peer reviewed?
No. It is a topline press release from the sponsor, issued September 22, 2026. There is no publication, no conference presentation, no posted results, and the release gives no ClinicalTrials.gov identifier for the study.
Was weight loss the primary endpoint?
The company's own January 2026 release describes the study objectives as safety, tolerability and pharmacokinetics, and lists body weight change as an exploratory endpoint. The September release leads with the weight figures.
Why do the two Viking releases give different week numbers?
The January release describes 19 weeks of induction and a study ending at Week 31. The September release describes 21 weeks and Week 33. The company has not explained the difference.
Does this apply to the VK2735 pill?
No. The oral maintenance arms were part of the planned design and were not reported in this readout. The company says it plans to explore oral maintenance regimens in a part 2.
Is VK2735 FDA approved, and when could it be available?
It has no approval from the FDA or any other regulator, and there is no legal route to it outside a trial. This maintenance study is not a registrational trial, and the company says it plans a part 2 to explore oral maintenance regimens, so it is not the study an approval would rest on. Where the wider Phase 3 programme stands is on our VK2735 compound page.
Can I buy VK2735?
It is not approved anywhere and there is no legal route to obtain it outside a trial. Research-labelled vials sold online are not the product tested in this study and carry no assurance of identity or content.
Did they measure muscle or lean mass?
The readout reports no body composition data, so whether the weight held during the maintenance phase was fat or lean tissue is not addressed. Lean tissue made up a substantial share of the weight lost in published trials of this drug class, and our guide on what happens after significant weight loss covers that.
How long did the maintenance phase run?
Twelve weeks, from Week 21 to Week 33. Questions about whether these regimens hold weight off over a year are not addressed by a three-month window.
Sources
- Viking Therapeutics. Viking Therapeutics Announces Positive Top-Line Results from Maintenance Study of GLP-1/GIP Agonist VK2735 Demonstrating the Promise of Multiple Maintenance Dosing Regimens. Press release, 22 September 2026. ir.vikingtherapeutics.com.
- Viking Therapeutics. Viking Therapeutics Announces Completion of Enrollment in Maintenance Dosing Clinical Trial of VK2735 in Obesity. Press release, 8 January 2026. ir.vikingtherapeutics.com.
- Rubino D, Abrahamsson N, Davies M, et al. Effect of continued weekly subcutaneous semaglutide vs placebo on weight loss maintenance in adults with overweight or obesity: the STEP 4 randomized clinical trial. JAMA 2021;325(14):1414-1425. doi:10.1001/jama.2021.3224. PMID 33755728.
- Aronne LJ, Sattar N, Horn DB, et al. Continued treatment with tirzepatide for maintenance of weight reduction in adults with obesity: the SURMOUNT-4 randomized clinical trial. JAMA 2024;331(1):38-48. doi:10.1001/jama.2023.24945. PMID 38078870.
Citing this page. Peptide Decoding. Can VK2735 Be Taken Once a Month? What the Maintenance Study Actually Tested. VK2735 figures from Viking Therapeutics topline press release of September 22, 2026 and enrolment release of January 8, 2026; comparator figures from STEP 4, JAMA 2021, and SURMOUNT-4, JAMA 2024. https://peptidedecoding.com/news/vk2735-monthly-maintenance