The number depends on which guideline your prescriber uses. A phase 3b trial in China and Taiwan enrolled adults at a BMI of 24 to under 28 [1]. That band required a weight-related condition, and a second ran 28 to under 30. Weight fell 12.1% against 2.2% on placebo over 44 weeks. East Asian guidelines set the cut-points lower because risk rises at lower BMI there. A cut-off is a convention adopted by a committee. It is not a line where a body changes. Nothing on this page tells you that you qualify.
Every intake form asks for a height and a weight. Behind it sits a number that decides whether anything is offered. That number is not a fact about bodies. It is a guideline, and guidelines differ. It is a different kind of gate from the state lists sellers publish, and it works the same way.
A trial run at lower numbers
STEP 12 enrolled adults across 19 sites in mainland China and Taiwan [1]. It used locally defined BMI thresholds. Entry was 24 to under 28 with at least one weight-related condition. The second band was 28 to under 30, with or without type 2 diabetes. Of 242 participants, 161 received semaglutide 2.4 mg weekly and 81 placebo. The trial ran 44 weeks alongside lifestyle intervention. Half were women and 19.4% had type 2 diabetes.
Those entry criteria sit below where the well-known trials began. The rationale is not novel. East Asian guidelines set overweight and obesity cut-points lower, because cardiometabolic risk rises at lower BMI in these populations. The trial was designed around the local definition rather than the American one.
What it found
Body weight fell 12.1% on semaglutide against 2.2% on placebo. The estimated treatment difference was 9.9 percentage points, 95% CI −11.8 to −8.0, p<0.0001. The proportion reaching at least 5% weight loss was 80.5% against 24.4%, an odds ratio of 14.8, 95% CI 7.4 to 29.6.
Adverse events were reported by 141 of 161 participants on the drug, 87.6%, and 61 of 81 on placebo, 75.3%. Both figures are high. The difference between them is smaller than the drug figure alone suggests. That is the reason to ask what the placebo arm reported.
What the threshold does after you clear it
Meeting the number is not the same as being coded for it. A decade-long analysis looked at 42,243 hospitalized adults with a measured BMI of 30 or above and no prior obesity code [2]. Obesity appeared in the discharge summary for 10.6% of them. Each additional BMI unit raised the odds of being coded by 17%. The threshold behaves as a gradient rather than a gate. Documented patients had 3.44 times the odds of a GLP-1 prescription. That is an association, not a cause, and the full reading is in measured in everyone, written down in one in ten.
Below the threshold entirely
One study went under it. A target trial emulation took adults with type 2 diabetes and a BMI below 27, the group the weight trials exclude [3]. Against DPP-4 inhibitors, all-cause mortality was 39% lower, hazard ratio 0.61, 95% CI 0.52 to 0.71. Against SGLT2 inhibitors it did not differ: 0.89, 95% CI 0.76 to 1.05. The authors say the mortality figure likely reflects residual confounding. Coded heart failure was lower across all three comparisons, which was their most consistent result. The reading is in the authors who doubt their own hazard ratio.
How it compares
The 12.1% reduction is smaller than the headline figures from the large Western trials. The comparison is not straightforward. This cohort started at a lower BMI, so there was less weight available to lose. The trial also ran 44 weeks rather than 68. Percentage weight loss behaves differently depending on where you start. That is one reason expected-loss estimates should never be read as a promise.
What travels is the shape. Both co-primary endpoints separated clearly from placebo. That is consistent with what the wider trial evidence shows. A drug that worked only where it was first tested would be the surprising result. This is not that.
Why a single trial in one region matters here
Most readers meet this drug through trials run in the United States and Europe. The generalization outward is usually assumed rather than demonstrated. Trials like this one test the assumption. They arrive years later and attract a fraction of the attention.
The published evidence is also narrower than the marketing implies at any moment. That is the gap separating a famous trial from the literature behind it. The trial was funded by Novo Nordisk, which makes the drug.