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 are common misconceptions 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.”
What are these weight-loss medications?
Obesity medications typically belong to a class of drugs known as glucagon-like peptide 1 receptor agonists, or GLP-1 RAs. This class of drugs now includes dual agonists for GLP-1/GIP. (GIP stands for glucose-dependent insulinotropic polypeptide.)
The medications approved by the Food and Drug Administration to treat obesity include:
- Semaglutide, branded as Wegovy
- Tirzepatide, branded as Zepbound
- Liraglutide, branded as Saxenda
Other GLP-1 RAs are approved by the FDA to treat Type 2 diabetes. Examples of these medicines are: semaglutide (branded as Ozempic and Rybelsus); liraglutide (branded as Victoza); tirzepatide (branded as Mounjaro); and dulaglutide (branded as Trulicity).
“Over the last couple years, data from trials have demonstrated additional health benefits from these medications, which have resulted in expanded FDA approvals,” Garner said.
The additional health benefits these drugs can provide include reducing the risk of heart and vascular disease; obstructive sleep apnea; and metabolic dysfunction-associated steatohepatitis (a serious type of fatty liver disease), Garner said.
“These drugs can cross the blood-brain barrier and cause a signal to our brain to tell us that we’re full.”
How these weight-loss medications work
GLP-1 and GIP are incretin hormones. That means they are peptides in the gut. (Peptides are short bits of amino acids, which in turn build proteins.) The body produces incretin hormones after you eat, to prompt the pancreas to make insulin, which lowers blood sugar.
These weight-loss medications mimic these natural hormones, but with a stronger effect.
“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 these gut hormones, GLP-1 and GLP-1/GIP RAs encourage the body to release insulin. The drugs also help prevent the death of cells in the pancreas that are responsible for that insulin 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,” Garner said. “But they also work on the brain.”
We have receptors in the hypothalamus, part of the brain. These receptors 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 include reducing inflammation and reducing major problems with the heart. They may also offer help protect nerve cells from damage. More studies are needed to understand these additional benefits.
Why medications for obesity are 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 counterproductive in 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 or GLP-1/GIP RA 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 encourages people who are struggling with obesity to talk to their doctors about 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 person to person depending on many factors, including other health conditions.
“GLP-1 or GLP-1/GIP RA are the best medications on the market right now for obesity,” Garner 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.”
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.
