As GLP-1 use for weight loss rises sharply across the United States, endocrinologist Dr. Rocio Salas-Whalen explains the science, side effects and medical considerations behind the treatment
MasterClass has launched a new course focusing on GLP-1 medications and weight management. “Understanding GLP-1s and Weight Loss” is taught by endocrinologist and obesity medicine specialist Dr. Rocio Salas-Whalen, who has more than 16 years of experience treating patients with GLP-1 therapies and was among the early adopters of these medications in the United States.
Rather than focusing solely on weight loss, the course examines what happens before, during and after GLP-1 treatment. Salas-Whalen explains the biological mechanisms that influence body weight, common side effects of the medications and the measures patients can take to preserve muscle and improve their metabolic health while losing weight.
GLP-1 use rises sharply across the US
The course arrives as GLP-1 medications move rapidly into mainstream use. According to a Gallup survey conducted in June 2026, 11 percent of US adults are now taking a GLP-1 medication for weight loss, compared with just 3 percent two years earlier.
Awareness has grown even faster. According to the figures cited by MasterClass, 91 percent of Americans now recognize GLP-1 medications by name.
Salas-Whalen says the drugs can have a major impact when used appropriately, but argues that many patients begin treatment without a comprehensive plan for what comes next. The course therefore focuses not only on losing weight but also on which health indicators patients should follow during treatment.
Side effects, muscle loss and dosage
Among the practical issues covered are nausea and fatigue, two common side effects associated with GLP-1 therapy. Salas-Whalen also addresses concerns that may accompany significant weight loss, including hair loss.
Another focus is the biology of weight gain. The course examines the roles of genetics, hormones, environmental influences and other biological factors, explaining why body-weight regulation is considerably more complex than a question of willpower alone.
Preserving muscle during weight loss is also addressed. Salas-Whalen presents the framework she uses with her own patients, including protein intake and strength training.
The course additionally explains the principles physicians consider when assessing dosage increases, treatment response and tolerability. The aim is to give patients a better understanding of these decisions and help them discuss their treatment with their healthcare provider.
“A GLP-1 is not a supplement”
“A GLP-1 is not a supplement or the diet du jour,” Salas-Whalen said. “It’s a prescription medication treating a chronic condition, and for the first time in history, we have medications designed not just to help people reach their goals, but to help them maintain them.”
She also stresses the importance of professional medical guidance. “The experience and guidance of the clinician prescribing these medications matter enormously.”
According to Salas-Whalen, fewer than 11,500 physicians in the United States specialize in obesity medicine. She designed the course to give patients the knowledge she wants her own patients to have so they can understand their treatment, ask better questions and advocate for themselves.
“An informed patient is an empowered patient,” she said.
Course available through MasterClass
“Understanding GLP-1s and Weight Loss” is now available exclusively through MasterClass. The course is included in the platform’s annual membership, which provides subscribers with access to classes from more than 200 instructors.
Image Credit: © AI generated illustration with material courtesy of MasterClass
