What to Know About Zepbound, a Weight Loss Drug to Rival Wegovy (2024)

The Food and Drug Administration (FDA) on Wednesday approved Eli Lilly’s tirzepatide for treating obesity.

Tirzepatide, which is already marketed as Mounjaro for treating type 2 diabetes, will be sold under the brand name Zepbound for weight management.

Based on Lilly’s clinical trial results, Zepbound is the most effective weight management medication on the market. The approval of Zepbound could improve access for patients who have struggled to get a hold of obesity medications amid drug shortages.

“It adds another option to our toolbox for treatment of patients with obesity. This means we can better tailor treatment for the patient with the goal of maximizing benefits and minimizing potential for side effects,” Jamy Ard, MD, president-elect of The Obesity Society, told Verywell via an email.

Following Wegovy, Zepbound is the second drug in a new class of medications to be approved for treating obesity.

“It signals that there is going to be continued development in the space of obesity treatment, which means more therapeutic options in the future,” Ard said.

How Does Zepbound Work?

Zepbound is indicated for adults who have a body mass index (BMI) of 30 or greater, or those with a BMI of 27 who also have a weight-related condition, such as high blood pressure or heart disease. It’s an injection medicine that is self-administered under the skin once weekly.

Zepbound contains tirzepatide, which stimulates two hormone receptors: glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP).

Like semaglutide, the active ingredient in Ozempic and Wegovy that targets GLP-1 receptors, tirzepatide can slow down digestion and help people feel fuller for longer. Tirzepatide also targets GIP receptors, which can help boost metabolism and lead to better weight and blood sugar management than GLP-1 agonists alone.

In Lilly’s clinical trials, adults without diabetes who received the highest approved dosage of Zepbound lost 18% of their body weight on average compared to those who received a placebo. People with type 2 diabetes saw a 12% body weight reduction at the same dosage.

One in three study participants taking the highest dose of Zepbound lost more than 58 pounds, or about 25% of their body weight. That’s compared to about 1.5% of patients on placebo who lost the same amount.

Losing 5% to 10% of body weight is associated with improvements in heart health, sleep apnea, and liver disease. In Lilly’s trials, 85% of participants lost at least 5% of their body weight at the lowest dose.

For people with obesity, drugs like Zepbound and Wegovy can be effective when lifestyle modifications alone fail to help them lose weight.

“For decades, diet and exercise have been a go-to, but it’s not uncommon for a person to have tried 20 to 30 times to lose weight with this approach. Research now shows that the body may respond to a calorie-deficit diet by increasing hunger and reducing feelings of fullness, making weight loss more difficult,” Leonard Glass, senior vice president of global medical affairs at LillyDiabetes and Obesity, said in a statement.

What Are the Side Effects of Zepbound?

As with the other GLP-1-based drugs, Zepbound may come with gastrointestinal side effects, such as nausea, diarrhea, constipation, stomach pain, and indigestion. In some studies, patients experienced vomiting, diarrhea, and nausea when their dosage amount increased, but those effects subsided over time.

According to the FDA, the drug can cause thyroid C-cell tumors in rats, though it’s not clear if it causes such tumors in humans.

How Much Will Zepbound Cost?

Lilly said the list price will be $1,060, about 20% lower than the list price for competitor Wegovy. The actual price for most patients may be lower after insurance coverage and discounts are factored in.

Since the debut of GLP-1-based drugs, however, insurers have been reluctant to cover the cost of medications for obesity—a condition that some 70% of Americans live with.

“Unfortunately, I’m less optimistic about any significant movement on insurance coverage with this approval,” Ard said. “The only way I see that happening is if there is better pricing for these meds.”

The FDA said people who take Zepbound should also focus on a healthy lifestyle, such as eating a balanced, reduced-calorie diet and getting adequate exercise.

“These medications make the work of losing weight much easier, but the patient has to ensure that the quality of weight loss is ideal,” Ard said. “This means there is still a need to consume a high-quality dietary intake and maintain or initiate a physical activity plan.”

It’s also important to keep in mind that Zepbound is a long-term treatment, he added.

“Obesity is not cured with these medications—it is simply controlled,” Ard said. “Stopping treatment increases the chances that weight will increase to some higher level. That’s just the biology of how this works.”