October 16, 2023

Learn about obesity drugs and why they’re a game changer for weight loss and overall health.

The media has been buzzing with news about weight-loss medications sold under various brand names. You might be wondering how these medications work, why they’re a breakthrough for treating obesity, and what the common misconceptions are about obesity and obesity drugs.

“These are phenomenal, game-changing medications that have improved the health and wellness of so many patients,” said Dr. Erica Garner, an obesity medicine specialist with the Vanderbilt Weight Loss Center. “We’re helping so many patients take back their health — not only their metabolic health, but also their mental health and their cardiovascular health.”

Weight-loss medications and how they work

Obesity medications typically belong to a class of drugs known as glucagon-like peptide 1 receptor agonists, or GLP-1 RAs. The only medications approved by the Food and Drug Administration to treat obesity include semaglutide 2.4mg (branded as Wegovy) and liraglutide 3.0mg (branded as Saxenda). Other GLP-1 RAs, such as semaglutide (branded as Ozempic and Rybelsus), liraglutide (Victoza), tirzepatide (Mounjaro), and dulaglutide (Trulicity) are FDA-approved to treat Type 2 diabetes.

“However, we can prescribe them off-label use if appropriate,” Garner said. “Also, Mounjaro is expected to have expanded FDA approval for obesity, in addition to diabetes, later this year.”

“These drugs can cross the blood-brain barrier and cause a signal to our brain to tell us that we’re full.”

GLP-1 is an incretin hormone secreted by the intestines, and GLP-1 RA medications mimic this hormone. “The body releases several gut hormones that help to regulate blood sugar and slow down the rate of digestion and then induce a sense of satiety so that people naturally stop eating when their body has met its metabolic need,” Garner explained. “In some diseases, like diabetes and obesity, these hormones are not functioning properly.”

By mimicking the GLP-1 hormone, GLP-1 RAs help stimulate insulin release and help prevent the death of pancreatic cells responsible for that release. They also help prevent the liver from releasing glucagon, which can raise blood sugar. “Part of the mechanism of weight loss is helping to regulate blood sugar because that’s very closely related to weight regulation. But they also work on the brain,” Garner said.

We have receptors in the hypothalamus that help with weight regulation and energy balance. “These drugs can cross the blood-brain barrier and cause a signal to our brain to tell us that we’re full,” Garner said. Other beneficial effects are that GLP-1 RAs may help with cardiovascular health and reduce inflammation. They may also offer some neuroprotection. More studies are needed to investigate these additional benefits.

Why are medications for obesity important

“For a long time, obesity was a very misunderstood disease,” Garner explained. She described the outdated concept that weight loss is a simple formula of burning more calories than one takes in. That concept has been proven false in medical studies. “The body is much more complex than that,” she said. “While calories do matter, they’re just a piece of the puzzle — not the whole story.”

“For a long time, obesity was a very misunderstood disease. While calories do matter, they’re just a piece of the puzzle.”

The body has a set point of weight that it is trying to defend. “When someone reduces their caloric intake, their metabolism slows down, too, because the body is inappropriately regulating a weight that is too high for someone’s health, which leads to downstream health effects,” she said. That reduced metabolism is counterintuitive to weight loss.

The body is supposed to regulate weight, just as it regulates many things, such as temperature and blood pressure. When people without obesity eat a meal, they stop eating when their body tells them they’re full. Even if someone eats a bit more, the body eventually signals to the brain, via hormones, that it can’t take in any more food.

Obesity is a disease of dysregulation and abnormal hormone signaling,” Garner explained. “Treating the disease with these medications helps restore that signaling and it helps promote weight loss by lowering caloric intake. But their metabolism does not slow down — unlike what happens when people just consume a lower-calorie diet.”

One thing that happens when someone takes a GLP-1 medication is that their brain becomes less preoccupied with food and the person stops snacking. “What happens is liberating for patients,” Garner added.

How to talk to your doctor about weight-loss medications

Garner wants to encourage patients who are struggling with obesity to talk to their doctors about their options. Her suggestion is to say, “I would like to hear about the benefits and risks of weight-loss medications and to see if these are a good fit for me.”

A primary care doctor may then prescribe a medication or refer you to an obesity medicine specialist who can provide you with options, which vary from patient to patient, depending on many factors, including other health conditions.

“GLP-1 receptor analogs are the best medications on the market right now for obesity,” she added. So in the majority of my patients with obesity, which is defined as a BMI greater than or equal to 30, these are going to be, most likely, my first choice for medications based on efficacy and safety in most settings.”

Woman holds up tape measure in foreground. Thumbnail sized image.

Help with weight loss

The Vanderbilt Weight Loss Center provides comprehensive, personalized care to help patients achieve and maintain their weight loss goals. Vanderbilt’s board-certified doctors are specially trained and experienced in all aspects of weight loss, partnering with a team of nurses, dietitians, exercise physiologists and psychologists to tailor treatment plans to meet each patient’s unique needs and health goals.

Learn More