Post-hoc analysis shows up to 13% weight loss in adults 65 and older

A post-hoc analysis of the ATTAIN-1 and ATTAIN-2 trials found that adults aged 65 and older lost up to about 13% of their body weight on orforglipron, the once-daily oral GLP-1 medicine sold as Foundayo ^[1]. The analysis, later published in the journal Obesity Pillars, looked specifically at whether an oral GLP-1 drug works as well in older patients as it does in younger ones ^[1].

The two trials together randomized 616 participants aged 65 or older, and 613 of them received treatment: 118 on the 5.5 mg dose, 135 on 9 mg, 146 on 17.2 mg, and 214 on placebo ^[1]. In ATTAIN-1, which enrolled people with obesity or overweight but without diabetes, weight loss at 72 weeks was -7.9% on 5.5 mg, -11.3% on 9 mg, and -13.0% on 17.2 mg, compared with -1.6% for placebo, with all differences statistically significant ^[1]. In ATTAIN-2, which enrolled people with obesity or overweight and type 2 diabetes, the numbers were -7.5%, -8.3%, and -12.2% across the same three doses, compared with -2.3% for placebo, again all statistically significant ^[1]. The researchers reported that these results in participants 65 and older were similar to those seen in people under 65 ^[1].

Side effects in the older group were mostly gastrointestinal and generally mild to moderate, and the overall safety profile was described as consistent with other GLP-1 receptor agonists ^[1]. The analysis pooled safety data across both trials rather than reporting it separately by trial ^[1].

These numbers sit alongside Foundayo's broader trial results reported by Eli Lilly. In the full ATTAIN-1 trial of 3,127 adults, people who stayed on the highest 36 mg capsule dose (equivalent to the 17.2 mg tablet) lost an average of 27.3 pounds, or 12.4%, versus 2.2 pounds, or 0.9%, on placebo ^[2]. Foundayo was approved by the FDA on April 1, 2026, for adults with obesity, or with overweight plus at least one weight-related medical condition, to be used along with a reduced-calorie diet and more physical activity ^[2].

Why it matters for patients

Older adults have historically been underrepresented in obesity drug trials, so data specific to people 65 and older can help patients and doctors weigh whether a GLP-1 medicine is likely to work for them and what to expect. This analysis suggests that, at least over 72 weeks, age on its own did not appear to blunt the drug's effect on body weight, and the safety pattern looked similar to what younger participants experienced ^[1].

Foundayo carries a boxed warning about the risk of thyroid C-cell tumors, along with warnings for acute pancreatitis, severe gastrointestinal reactions, acute kidney injury from fluid loss, low blood sugar, serious allergic reactions, and other risks ^[2]. Common side effects reported in at least 5% of patients include nausea, constipation, diarrhea, vomiting, dyspepsia, abdominal pain, headache, bloating, fatigue, burping, acid reflux, gas, and hair loss ^[2]. The post-hoc analysis did not report separately whether these specific side effects occurred at different rates in people 65 and older versus younger patients, and that detail is not yet known from the sources reviewed here ^[1].

Because this is a post-hoc, or after-the-fact, subgroup look rather than a trial designed from the start to study older adults, the findings are considered supportive evidence rather than a stand-alone confirmation of efficacy in this age group ^[1].

What happens next

The subgroup findings were reported around May 22, 2026, and later appeared in Obesity Pillars ^[1]. Foundayo, approved April 1, 2026, continues to generate additional trial data, including results from ACHIEVE-4 on cardiovascular and overall safety reported April 16, 2026, and Phase 3 diabetes trial results reported June 8, 2026 ^[2]. No further trial specifically targeting older adults with obesity was described in the sources reviewed.