The Obesity Society (TOS), the leading scientific organization for the study and practice of obesity medicine, held Obesity Week, its annual international meeting, in Atlanta from Nov. 4-7, 2025. Even as an experienced obesity medicine clinician, I always return home from this conference saturated with new research findings, clinical practice pearls, and an expanded network of contacts from around the world. The field of obesity medicine is progressing at such a head-spinning speed that it is sometimes difficult to keep up. Among various tracks, attendees learned from experts in different domains, ranging from behavioral and lifestyle approaches to the molecular and cellular mechanisms of weight regulation, stigma and bias, public health policy, anti-obesity pharmacotherapy, and metabolic bariatric surgery. I noticed three prominent themes throughout ObesityWeek.
First, discussions surrounding efforts to better refine definitions of clinical obesity garnered some feisty questions and impassioned arguments. Although BMI has a direct relationship with body fat and has served as a surrogate for adiposity, the consensus is that it is an imperfect measure since it fails to inform us about body composition, fat distribution, or pathogenic consequences for an individual patient. Rather, BMI is best utilized to study large populations. It follows that we do not have great standards for specific races and ethnicities. In fact, merely using BMI for diagnostic or therapeutic decision-making may misalign limited resources and those with the highest risk to their health. It may underdiagnose or overdiagnose obesity as a disease state.
There are efforts to refine this definition, which includes a group of international experts spanning multiple disciplines who, almost a year ago, published the Lancet Commission for the Definition and Diagnostic Criteria of Clinical Obesity (the “Commission”). The Commission has developed a diagnostic algorithm to define obesity similarly to how other chronic diseases are stratified. The report is a worthwhile read and, briefly, recommends assessing for clinical obesity, defined by BMI with confirmation of excess adiposity, by direct measure, or — more realistically — in most clinics, with anthropometric measures such as waist circumference. The Commission also recommends that the next step is to assess clinically for adverse effects, including symptoms, biomarkers, psychosocial and functional impacts, or evidence of end-organ dysfunction. Among attendees, these recommendations clashed with challenges of implementation in the real world. Some commissioners, who were present at the meeting, emphasized that their report is just a first step towards further evolving and refining how we define clinical obesity.
The second theme, unsurprisingly, revolved around existing and emerging pharmacotherapies. There are dozens of molecules in various stages of development. Currently, two oral anti-obesity medications are under review by the FDA, and if approved, they could be available in the next few months. There were several presentations regarding their efficacy, safety, and tolerability. The first medication discussed was high-dose oral semaglutide, the same active pharmaceutical ingredient in subcutaneous Wegovy and Ozempic, and the currently available oral formulation, Rybelsus, for type 2 diabetes. Weight loss effectiveness seems to be quite similar to the injectable formulation. The second agent is orforglipron, a non-peptide small molecule, taken once a day. There were also many oral and poster presentations on other drugs in the pipeline, with mechanisms of action including GLP-1 (glucagon-like peptide 1) monotherapy and co-agonism with many other nutrient-stimulated hormone mimetics (GIP, glucagon, amylin); targeting specific receptors in the hypothalamus for more rare obesity conditions; cannabinoid receptor antagonists; centrally acting agents; and muscle preservation therapies. Coincidentally, the excitement for these expensive and often inaccessible therapies was augmented by the Trump administration’s synchronous negotiations with the big drugmakers to lower costs, the very same week as the conference.
Finally, as anti-obesity pharmacotherapy steals the spotlight from other obesity topics, we continue to think about how other modalities fit in. There were quite a few presentations on lifestyle interventions, but more specifically, how to think about nutrition, physical activity, and other behavioral strategies in the era of GLP1-based therapies. One presentation was titled, “Is lifestyle change dead in the age of highly effective obesity management medications?” While most obesity medicine clinicians would agree that lifestyle is still foundational and critical, the discussions tended to focus on the premise that it may not be as important for weight reduction, but more for health optimization.
And still other talks focused on bariatric surgery, specifically how to integrate bariatric interventions with anti-obesity medications. The message that came through from experts and key opinion leaders was that although surgical procedure volumes may decline with the advent of even more potent medications, metabolic bariatric surgery still has an important role to play for certain patients. Simply put, in many cases, individuals will need a very comprehensive approach, with surgical and medical therapies working in synergy.
All that said, we all look forward to much more research for optimizing screening, diagnosing and optimizing care for our patients with obesity and related complications. I’m excited for ObesityWeek 2026 in Washington, D.C., to hear about all the exciting updates forthcoming on all aspects of obesity care.
Dr. Grunvald has received consulting fees or honorarium from Novo Nordisk, Eli Lilly, Aardvark Therapeutics, and Metsera.
Image by GoodStudio / Shutterstock
