By Dr. Asnat Raziel, bariatric surgeon specializing in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal, Tel Aviv
Lilly at ObesityWeek: what to expect in Washington
What will Lilly present at ObesityWeek? The American obesity congress runs in Washington from November 14 to 17. Therefore, Lilly is showing several important studies there. The main theme is a question almost every patient asks me. What happens to your weight once the weight-loss phase ends? Lilly will also present body composition data for the Foundayo pill. There is lab research on a new amylin drug, too.
I went through the congress program and the published poster list. Lilly has not yet issued a press release for the meeting. So this article draws on the official program and the original studies. I previously reviewed what Novo Nordisk will present at the congress.
Lilly at ObesityWeek: keeping the weight off in SURMOUNT-MAINTAIN
Two posters at the congress come from the SURMOUNT-MAINTAIN trial. It looked at life after more than a year on tirzepatide. Tirzepatide is the active ingredient in Mounjaro (the US brand for obesity is Zepbound).
First of all, the trial enrolled 441 adults with obesity. First, everyone took tirzepatide at the highest dose they tolerated for 60 weeks. Next, the researchers randomly split 378 participants into three groups. One group stayed on the same dose, one stepped down to 5 mg, and one switched to placebo. After that, each group continued for another year.
What the researchers found
Here are the full results in The Lancet. After about two years, people on the full dose had lost 21.9% of their body weight on average. Those on the reduced dose had lost 16.6%. In contrast, people who moved to placebo kept a loss of only 9.9%. In other words, much of the weight came back after stopping treatment.
The researchers also allowed rescue treatment. It was for anyone who regained over half of the lost weight. Of the placebo group, 67% needed it. That compares with 25% on the reduced dose and 8% on the full dose.
What Lilly will show at ObesityWeek
One poster looks at body composition. How much fat and how much lean mass did people lose? In addition, a second poster counts how many people reached clinical goals. Examples are blood pressure and blood sugar targets. Both matter, because success means more than kilograms.
Lilly at ObesityWeek: switching from an injection to a pill
I often hear this question in clinic. Can you move from a weekly injection to a daily pill without regaining weight? Foundayo is a GLP-1 pill whose active ingredient is orforglipron. You can take it at any time of day, with or without food.
The ATTAIN-MAINTAIN trial asked exactly this. It enrolled 376 people who had finished Wegovy or tirzepatide injections. Then they switched to Foundayo or placebo for one year. The figures come from Lilly’s announcement. People who switched from Wegovy kept 82.4% of their weight loss. In other words, they regained 0.9 kg on average. Similarly, those who switched from tirzepatide kept 78.0% and regained an average of 5.0 kg. By contrast, the placebo group had already regained about 9 kg after 24 weeks.
A poster at the congress covers eating control and food cravings after the switch. Put simply, does the pill keep the internal noise around food quiet?
Lilly at ObesityWeek: body composition on Foundayo
Moreover, another poster analyzes body composition in ATTAIN-1, the large phase 3 trial of Foundayo. It enrolled 3,127 adults with obesity and without diabetes. The results appeared in NEJM. After 72 weeks, weight loss on the highest dose was 11.2%, versus 2.1% on placebo. On the highest dose, 36.0% of patients lost 15% or more of their weight.
Now, the new question is where the lost weight came from. Ideally, good weight loss is mostly fat, while keeping as much muscle as possible. That is why, even on medication, I recommend strength training and enough protein.
Lilly at ObesityWeek: the amylin drug eloralintide
Eloralintide is an investigational drug that acts on the amylin receptor. Specifically, amylin is a hormone that boosts the feeling of fullness. No regulator has approved it, and it is now in phase 3 trials.
In a phase 2 trial published in The Lancet, 263 adults took part. After 48 weeks, weight loss reached up to 20% on the highest dose. By contrast, on placebo it was 0.4%. The most common side effects were nausea and fatigue.
Finally, Lilly will also show two lab studies at the congress. First, one looks at how the drug reduces eating without causing a feeling of illness. The second looks at what happens when researchers add it to tirzepatide. However, these are animal studies, so they cannot yet tell us much about people.
Lilly’s educational sessions at the congress
Besides the posters, Lilly is holding four professional sessions for physicians:
- A session on treatment with Foundayo – Sunday, November 15, in the morning.
- A multidisciplinary roundtable on one patient seen from many angles – Sunday evening.
- Weight bias and stigma in pediatric care – Monday morning, November 16.
- A session on tirzepatide injection – Monday at midday.
Above all, I was especially glad to see a session on stigma in children. After all, respectful care is part of the treatment itself.
What we don’t know yet
The oral research presentations are under embargo until the congress opens on November 14. So Lilly may show new data, for example on retatrutide. No regulator has approved this investigational drug. Meanwhile, I will update as results come out.
Bottom line
The main message of Lilly at ObesityWeek is clear. In short, obesity is a chronic disease, and its treatment is long term. For example, people who stop the medication usually regain much of the weight. Still, a lower dose or a pill may offer a good middle path. In the end, make this decision together with your doctor.
This article is general information and is not personal medical advice. Make any treatment decision with your treating physician.
References
ObesityWeek 2026: Corporate Supported Symposia
ObesityWeek 2026: Posters by Title
Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment
Eli Lilly funded the studies.
