Reviews/GLP-1 Receptor Agonists/Semaglutide 2.4 mg achieves 15% body weight loss
Metabolic · GLP1-MET-04 · v2
Borderline: within 4 points of the Established/Likely boundary, so a re-grade could land either side.
Several large, blinded, high-quality trials of semaglutide 2.4 mg weekly in people with obesity but not diabetes landed very close to the same number: around 14.9% to 16.0% average weight loss [9][3][6][4]. A real-world study of people who stayed on the drug for a year found similar results, about 14.5% to 14.8% [16]. The figure is notably smaller in people who also have type 2 diabetes, about 9.6% [2], and in a long-term heart-disease population, about 10.2% over four years [18]. The panel read 'patients with obesity' as the standard obesity-without-diabetes group, where the roughly 15% figure is well supported. It noted the lower numbers in other groups as a limit on scope rather than a reason to reject the claim.
Four double-blind phase-3 RCTs in obesity without diabetes converge on the target figure: -14.9% [9], -16.0% [3], -15.2% at 104 weeks [6], and -15.8% [4], with a STEP 1 extension subset reporting 17.3% [5]. A real-world US cohort restricted to one-year persisters reported -14.5% at 52 weeks and -14.8% at 68 weeks [16]. In type 2 diabetes the estimated mean change was -9.6% [2], and in the long-term cardiovascular cohort -10.2% at 208 weeks [18]. A head-to-head trial using max-tolerated (1.7 or 2.4 mg) semaglutide reported -13.7% [11]. The contested point: The division is over how broadly 'patients with obesity' is read: the ~15% figure holds in the obesity-without-diabetes trial population but falls to -9.6% in type 2 diabetes [2] and -10.2% in the long-term CVD cohort [18]. A secondary question is how much of the pivotal figure depends on intensive behavioral therapy [3] versus the cleaner drug-plus-lifestyle estimate of -14.9% [9].
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One reviewer's only job is to attack the finding. The challenges below were weighed before the grade was set.
The ~15% figure holds for obesity WITHOUT diabetes; in the type 2 diabetes population it is only -9.6% [2] and in the long-term established-CVD cohort only -10.2% at 4 years [18]. A reading of 'patients with obesity' that includes these groups overstates the effect.
All STEP RCTs supplying the ~15% figure [1-6,9] share one sponsor (Novo Nordisk); independent corroboration rests on real-world cohorts where survivorship inflates the number (SCOPE's -14.8% is measured only in patients who remained on treatment a full year [16]).
Where it remains uncertain. The figure drops to -9.6% in type 2 diabetes [2] and -10.2% over four years in the cardiovascular cohort [18], so a population reading that includes these groups overstates the effect.
Aleatory
Reported means sit alongside wide responder distributions; e.g. STEP 1 shows 50.5% versus others not reaching ≥15% loss [9], so individual outcomes vary around the mean.
Epistemic
The corpus does not fix whether 'patients with obesity' includes type 2 diabetes, where the figure is -9.6% [2], or long-term CVD cohorts at -10.2% [18].
Inferential
SCOPE's -14.5% to -14.8% is measured only in patients who remained on treatment for a full year [16], so it may overstate the average starter's result.
The load-bearing papers from a corpus of 21, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Scope caveat: in type 2 diabetes the loss is ~9.6%, below the 15% figure.
“Estimated change in mean bodyweight from baseline to week 68 was -9·6% (SE 0·4) with semaglutide 2·4 mg vs -3·4% (0·4) with placebo”
Panel auditInternal validity: high · scope of inference: Adults with overweight/obesity and type 2 diabetes on background glucose-lowering therapy.Key limitations: type 2 diabetes population · not the obesity claim's population
STEP 3: -16.0% with intensive behavioral therapy, at upper edge of ~15%.
“At week 68, the estimated mean body weight change from baseline was -16.0% for semaglutide vs -5.7% for placebo”
Panel auditInternal validity: high · scope of inference: Adults with overweight plus comorbidity or obesity, without diabetes, receiving 30 behavioral-counseling visits plus initial low-calorie diet.Key limitations: intensive behavioral therapy may augment effect · US-only sites
STEP 8: -15.8% in obesity without diabetes, independent replication.
“The mean weight change from baseline was -15.8% with semaglutide vs -6.4% with liraglutide”
Panel auditInternal validity: high · scope of inference: Adults with overweight/obesity without diabetes; some unable to tolerate 2.4 mg received 1.7 mg.Key limitations: open-label active comparison · small semaglutide arm · dose reduction to 1.7 mg permitted
STEP 1 extension subset: on-treatment loss at or above 15%.
“From week 0 to week 68, mean weight loss was 17.3% (SD: 9.3%) with semaglutide and 2.0% (SD: 6.1%) with placebo”
Panel auditInternal validity: medium · scope of inference: A geographic subset of STEP 1 completers with BMI ≥30 (or ≥27 with comorbidity) without diabetes.Key limitations: exploratory subset · completers only · not a formal significance test of the 17.3% figure
4 of 21 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
Convergent, methodologically strong, multi-trial primary evidence places the mean loss at 14.9-16.0% in the target obesity population, matching 'approximately 15%'.
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
Real-world estimate including non-persisters. The real-world figure is restricted to one-year persisters [16], so survivorship may inflate it relative to all starters. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: An intention-to-treat real-world cohort reporting mean weight change across all initiators regardless of discontinuation.
Open question: Does mean weight loss with semaglutide 2.4 mg reach ~15% across all obese patients, or only in those without type 2 diabetes or established cardiovascular disease? Why it is still open: The corpus reports -9.6% in type 2 diabetes [2] and -10.2% in the SELECT CVD cohort [18], against ~15% in the obesity-without-diabetes trials [9][3][6][4].
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 21 Oct 2026 · protocol v0.19