If you aren’t getting results on a GLP-1 weight-loss medication, Dr. Imaeda says the first step is to look at your diet.
“Sometimes people haven’t made meaningful dietary changes,” Dr. Imaeda says. “They may still be drinking soda or eating fast food, which can either make them feel sick or limit how well the medication works.”
Certain medical factors, such as thyroid disorders, can disrupt metabolism. She also evaluates blood sugar control, often measured by hemoglobin A1C, which reflects average glucose levels over several months. People with impaired glucose regulation, including those with diabetes, tend to lose less weight on these medications.
It’s also possible that another underlying condition, perhaps a less common one, could play a role. “Sometimes, despite doing everything right, a patient just doesn’t respond the way we’d hope,” she says.
And this isn’t unique to weight-loss medications—some patients may not respond to certain blood-pressure drugs, antidepressants, or cancer therapies. Biology is complex, and treatment responses can vary widely from person to person.
That variability shows up consistently in studies and among patients, says John Morton, MD, MPH, chief of Yale Medicine Bariatric and Minimally Invasive Surgery and a board-certified obesity medicine specialist.
“Across clinical trials, about 10% of patients see little to no weight loss with GLP-1 medication,” Dr. Morton says. “I avoid using terms like failure as it can imply a personal responsibility for weight loss when genetic, treatment-related, or environmental factors may be the cause of non-response,” he says.
In practice, he adds, those patients who don’t respond often have more advanced obesity, with a body mass index (BMI) above 40—a group that has been underrepresented in many GLP‑1 studies, where the average BMI has typically been in the mid‑30s. BMI is a measure of body weight relative to height, commonly used to assess obesity.
