The conversation around weight-loss medications can make it sound as though the only question is whether a prescription works. A new clinical guideline from the American College of Physicians takes a more careful view.
The guideline, published in the Annals of Internal Medicine, recommends semaglutide and tirzepatide as first-line options when eligible adults begin medication treatment for weight management, but not as stand-alone fixes. ACP says these medications should be used with lifestyle modifications, including improved nutrition and physical activity, and decisions should account for benefits, harms, cost, access, availability, health conditions, personal goals and patient preferences.
The new guidance applies to nonpregnant adults with obesity, defined in the guideline as a body mass index of 30 or higher, and to adults with overweight, defined as a BMI of 27 to less than 30, who also have at least one related condition such as type 2 diabetes, high blood pressure, dyslipidemia, obstructive sleep apnea or cardiovascular disease.
For adults with obesity, ACP recommends semaglutide and tirzepatide as first-line options when starting medication treatment with lifestyle modifications. The guideline lists phentermine-topiramate as a second-line treatment, liraglutide as a third-line treatment and naltrexone-bupropion as a fourth-line treatment.
For adults with overweight and at least one related health condition, ACP recommends semaglutide or tirzepatide as first-line options and liraglutide as a second-line treatment, again with lifestyle modifications.
The guideline is not a new trial testing these medications in one experiment. It is a clinical guideline based on evidence reviews of available research on medication benefits, harms and cost-effectiveness. ACP also designated it as a “living guideline,” meaning the recommendations are expected to be updated as new evidence becomes available.
That matters because obesity medications are changing quickly. GLP-1-based medications and related therapies have reshaped the weight-management landscape, but the practical questions around them are still evolving. How long should someone stay on medication? What happens if they stop? How should nutrition be adjusted when appetite drops? How should patients and clinicians weigh cost, insurance coverage and side effects?
ACP’s guidance does not answer every question, but it does make clear that medication choice should not be based only on pounds lost. The group says clinicians and patients should discuss possible harms, contraindications and warnings, as well as life expectancy, comorbidities and individual values.
The guideline also calls attention to a less flashy but important issue: rapid or significant weight loss can have unintended effects. ACP says clinicians should counsel patients about possible nutritional deficiencies and loss of muscle and bone density, especially in older adults.
That does not mean people should avoid these medications when they are appropriate. It means weight loss should not be treated as the only measure of success. Preserving strength, getting enough essential nutrients and maintaining long-term health are part of the picture, too.
BMI is also only part of the decision. While ACP uses BMI categories to define who the guideline applies to, BMI does not capture everything about a person’s health, body composition or risk. The guidance still points back to individualized decision-making between patients and clinicians.
Financial support for the development of the ACP guideline came exclusively from the American College of Physicians operating budget. ACP reported that financial and intellectual disclosures were declared, discussed and managed. Two Clinical Guidelines Committee members were recused from authorship and voting because of conflicts of interest.