Two abstracts at the European Congress on Obesity 2026 in Istanbul ↗ (May 12-15) are filling a clinical gap that has shadowed obesity-drug prescribing for the past three years. A Padova-led pooled analysis of semaglutide ↗ 2.4 mg in 358 adults aged 65 or older from the STEP 1, 3, 4, 5, 8, and 9 trials reports 15.4 percent mean body-weight loss vs 5.1 percent on placebo over the trial follow-up window. A Lilly-led post-hoc subgroup analysis of orforglipron (Foundayo) pools 616 adults aged 65 and older from the ATTAIN-1 and ATTAIN-2 Phase 3 programs, the small-molecule oral GLP-1 receptor agonist's first proper read on the same population. Both peptide and pill obesity drugs are getting their first systematic geriatric efficacy and safety profile in the same week.
Why the gap exists. The pivotal Phase 3 obesity trials of the past decade skewed younger. STEP and SURMOUNT enrolled adults from 18 upward, with median ages typically in the mid-to-late 40s and modest representation of patients over 65. Regulators approved semaglutide 2.4 mg, tirzepatide ↗, and now orforglipron based on those trial populations, with prescribing labels that do not restrict use in older adults but also do not anchor it. Clinicians have prescribed the drugs to patients over 65 since the launches, drawing inferences from the pooled populations and from individual patient response. The data those clinicians have wanted, the proper geriatric subgroup analysis with weight-loss magnitude and safety signal separated from the broader trial population, has lagged behind the prescribing reality. ECO 2026 is the venue at which the lag is closing.
The Padova numbers. The semaglutide 65+ analysis covers 358 adults (248 on 2.4 mg, 110 on placebo), mean age 69, 72 percent women. Weight loss was 15.4 percent on semaglutide vs 5.1 percent on placebo. The clinically meaningful weight-loss thresholds tracked together. 46.8 percent of semaglutide users hit at least 15 percent weight loss vs 6.4 percent on placebo. 28.6 percent reached at least 20 percent weight loss vs 2.7 percent. Waist circumference fell 14.3 cm on semaglutide vs 6.0 cm on placebo. 27 percent of semaglutide-treated patients reached a healthy BMI (below 27) by the end of follow-up vs 5.5 percent on placebo. The efficacy looks essentially the same as in the broader STEP populations, with the geriatric subgroup not showing the diminished response some clinicians had worried about. Serious adverse events occurred in 19.0 percent of semaglutide-treated patients vs 12.7 percent on placebo, an absolute difference of 6.3 percentage points consistent with the broader STEP safety profile. The investigator team is led by Prof. Luca Busetto at the University of Padova.
The Lilly orforglipron pool. Lilly's ECO 2026 post-hoc analysis covers 616 randomized adults aged 65 and older drawn from ATTAIN-1 and ATTAIN-2 (118 on 6 mg, 135 on 12 mg, 146 on 36 mg orforglipron, 214 placebo), spanning patients with and without type 2 diabetes. The specific efficacy numbers will land with the poster presentation; the design pool is the largest geriatric pool of a GLP-1 oral pill ever assembled. Lead author Dr. Deborah Horn at UTHealth Houston McGovern Medical School. The analysis matters for two reasons beyond filling the data gap. First, orforglipron is the first oral GLP-1 product that does not require fasting, water restriction, or SNAC absorption enhancement, which makes the polypharmacy and adherence considerations relevant to geriatric prescribing materially different from the injectable peptides. Second, the same Phase 3 program (ATTAIN) covers both obesity and T2D indications, so the geriatric subgroup carries cross-indication efficacy and tolerability signal in a way few other recent trials have.
What the data already tell you. The semaglutide numbers are the headline. 15.4 percent average weight loss is essentially indistinguishable from the broader STEP 1 efficacy in younger adults (STEP 1 reported 14.9 percent at 68 weeks in a mostly-under-65 population). The number that matters for prescribers is the absence of a meaningful efficacy decrement in older adults. The geriatric population has not been responding less well to incretin therapy than the broader trial pool; it has simply been understudied. The Padova analysis closes that question for semaglutide 2.4 mg. The Lilly orforglipron pool, when its efficacy numbers come out at ECO, will close the analogous question for the first non-peptide oral product in the class.
The safety side has one nuance worth holding. 19.0 percent SAEs on semaglutide vs 12.7 percent on placebo is a meaningfully elevated rate, consistent with the broader STEP pool. The number is not surprising in a population with substantially more baseline cardiovascular and other comorbid disease than the typical Phase 3 obesity-trial enrollee. The decision relevant to clinicians is whether the 10.3-percentage-point absolute weight-loss benefit and 21.5-percentage-point increment in the proportion reaching 20 percent weight loss is worth the 6.3-percentage-point absolute increase in SAE risk in a given patient. That is a calculation the broader literature on obesity-mortality association already supports for most over-65 patients with baseline BMI above 30, but the trial-level number now anchors that conversation explicitly.
The platform read. The platform's GLP-1 receptor corner already hosts the agonist scaffolds that anchor the obesity drug class, and the geriatric efficacy data does not change the molecular design questions the platform cares about. What it does change is the boundary condition on the addressable patient population. Adults over 65 represent roughly 17 percent of the US population, an outsize fraction of patients with obesity-related comorbid disease, and the population whose prescribing has been most constrained by the missing trial data. The two ECO analyses move that population from extrapolation territory to evidence-based prescribing territory, which is the gating step before broader geriatric reimbursement decisions and revised society guidelines come online.
What this is not. A new safety alarm, and not a recommendation to expand prescribing without considering baseline frailty and polypharmacy. The SAE rate is higher in older patients than in younger ones in absolute terms, and the clinical decision still depends on individual baseline risk. What it is is the first clean evidence anchor for prescribing decisions in a population that has been managed on inference for three years. The geriatric obesity-drug data gap is finally closing, and both halves of the GLP-1 product class, peptide and small-molecule, are getting their first proper read in the same week.