How does Zepbound work for weight loss?

Zepbound, the newest FDA-approved weight-management medication, has been shown to be highly effective for weight loss. Here’s everything you need to know.
Published June 2, 2023 | Updated May 10, 2024
Zepbound for Weight LossZepbound for Weight Loss

In this article:

1/ Zepbound (tirzepatide) basics

2/ How Zepbound works

3/ Zepbound side effects

4/ Efficacy for weight loss

5/ Length of treatment

6/ Dosage details

7/ Key lifestyle changes

8/ The bottom line

This content is for informational purposes only and does not constitute medical advice, diagnosis or treatment. It should not be regarded as a substitute for guidance from your healthcare provider.

First came liraglutide, then semaglutide. Now, tirzepatide—known by the brand name Zepbound—is another GLP-1 (glucagon-like peptide-1 agonist) drug FDA-approved for obesity. But while it may be the third, it’s also the first of its kind in the GLP-1 class of drugs. It works by mimicking two types of hormones instead of just one. So what does that mean when it comes to weight loss? Let’s catch you up on the details.

What is Zepbound (tirzepatide)?

Zepbound is the brand name for tirzepatide, a type of GLP-1 drug that’s administered weekly via self-injection for weight loss. Research in the New England Journal of Medicine shows that people living with obesity and without diabetes who took the drug for weight loss in combination with healthy lifestyle practices lost an average of 21% of their total body weight in just over a year.

Zepbound for weight loss: How does it work?

What makes tirzepatide unique is that it doesn’t just target the gut hormone known as GLP-1. It also targets another gut hormone, something called gastric inhibitory polypeptide (GIP), which functions in a similar way as GLP-1, says Dr. Dexter G. Turnquest, M.D., bariatric medical director at Houston Methodist Willowbrook Hospital in Houston, Texas.

By mimicking the effects of both GLP-1 and GIP, Zepbound doubles down on their workload in the body. It tells your brain and your gut you’re satisfied, so “you get fuller with less food,” says Dr. Stephanie Ortiz Page, D.O., medical director for the Metabolic and Medical Weight Loss Center at Nuvance Health in Wilton, Connecticut,, which is one of the ways it works for weight loss.

Importantly, Zepbound (like other GLP-1s) continues to work even as you lose weight. Normally, the body responds to weight loss by increasing appetite in order to get you back to your set point or original weight, explains Dr. Rutuja Patel, D.O., director for medical weight loss at Northwestern Medicine Central DuPage Hospital in Winfield, Illinois. By improving metabolic functions and appetite control long-term, weight-management medications like Zepbound can address the biological underpinning of obesity and help people maintain their weight-loss momentum.

Is Zepbound (tirzepatide) FDA-approved?

Another version of tirzepatide, Mounjaro, has been FDA-approved for the treatment of type 2 diabetes since May 2022. Zepbound was fast-tracked for approval by the FDA for obesity, which it received in late 2023. As with other weight-management medications, it is recommended for someone with a BMI over 30—or between 27-29.9 if you have an obesity-related condition like high blood pressure, diabetes, or high cholesterol.

What to know about Zepbound (tirzepatide) side effects

Like other GLP-1s, tirzepatide can come with side effects—though they don’t affect everyone, and they’re typically mild to moderate. You may feel them more when you first start or go up in dosage, but they’ll likely taper as your body gets accustomed to the medication, says Patel. The manufacturer’s site provides a full list of potential side effects, but the most common are GI issues, which isn’t all that surprising considering the drug targets gut hormones, says Ortiz Page. This includes:

  • Nausea
  • Diarrhea
  • Constipation
  • Bloating
  • Vomiting
  • Heartburn

There can also be other serious side effects. Zepbound and other GLP-1s may cause gallbladder inflammation and gallstones, as well as hypoglycemia (low blood sugar). Pancreatitis—an inflammation of the pancreas—is also possible. “That's acute, severe abdominal pain with nausea and vomiting,” says Patel. You would know it’s pancreatitis (instead of run-of-the-mill nausea) because you’d have pain in addition to queasiness. If that happens, call your provider immediately, says Patel. Also, if you have a history of pancreatitis, your provider may decide that GLP-1s aren’t the best medication for you.

Other conditions that may exclude GLP-1s like tirzepatide from your options? A personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 1. Early studies on prescription weight-loss drugs found that some rats developed thyroid cancer while on it, though the evidence in humans shows no increased risk.

“We would also be more cautious with those patients who have underlying GI conditions,” notes Ortiz Page. This includes gastroesophageal reflux or slow digestion (gastroparesis). “They may have a harder time tolerating the medication, so we’d monitor them more closely.”

5 ways to manage those GI side effects

Nausea won’t last forever, but that’s cold comfort for anyone actively dealing with it as a result of medication. While your body gets used to the drug or the new dose, consider these tips.

  1. Consume smaller, more frequent meals. A tip that says to eat less to lose weight? Groundbreaking. But bear with us here. GLP-1 drugs like Zepbound slow down digestion; as a result, food sits in your stomach a little longer, which may cause queasiness. Making portions a little smaller can help you handle it.

  2. Eat more mindfully. By eating more slowly and savoring each bite, says Ortiz Page, you give your GLP-1 and GIP hormones more time to respond, so you’ll feel full without overeating. “Once you start eating past that, you can trigger severe nausea, maybe even vomiting,” she explains.

  3. Work with your clinician on finding the right dose for you. Your healthcare provider may decide to lower the dose or wait to increase the dose until after your symptoms go away, Patel says. Give your body time to adjust and it may repay you with minimal effects.

  4. Avoid overly acidic foods. They can trigger acid reflux, says Ortiz Page. Exactly which acidic foods cause heartburn may vary from person to person, so it’s good to track what you eat (a cornerstone of the WeightWatchers program) so you can identify and avoid them. Some common culprits: hot salsa, orange juice, and even raw onion. As always, please consult your healthcare provider before making dietary changes.

  5. Take an anti-nausea medication. If recommended by your healthcare provider, consider taking an anti-nausea medication, which can help settle your stomach short-term until you get adjusted to your dose. But, says Ortiz Page, “if you need [anti-nausea meds] every day for a month, then this may not be the right dose for you—or the right medication.”

How much weight can you lose with Zepbound (tirzepatide)?

In one study published in The New England Journal of Medicine, researchers followed 2539 people living with obesity. Those on the lowest dose (5 mg) of tirzepatide had lost an average of 15% of their body weight after one year and three months. Those on the highest dose (15 mg) lost an average of roughly 21%. Additionally, those taking tirzepatide versus placebo also improved their overall health—lowering blood sugar, blood pressure, cholesterol, and triglyceride levels. Participants in the study also met regularly with a dietitian or other healthcare professional and were encouraged to eat a healthy, balanced diet and work out for at least 150 minutes a week.

How you respond to the medication depends on a few factors, including genetics, underlying health conditions, your lifestyle, and even where you tend to store body fat, says Ortiz Page. “Some people may start losing two or three pounds a week just on the starter dose at 2.5 mg. Some people lose one pound a week. And some people lose no weight,” she notes.

How long should you take Zepbound (tirzepatide)?

Obesity is a chronic disease, which means it requires continual treatment. “This is a lifelong drug,” says Patel. “When we start these meds, [part of the] discussion is that you’re going to need them for the long term.”

If you stop taking a GLP-1, odds are your weight will increase. Your body will start to secrete hormones that increase hunger and decrease fullness after eating. “When this tug of war happens, then people are going to start seeing weight gain,” says Patel.

If you switch from your provider’s prescription to a so-called Zepbound (tirzepatide) dupe, your results could suffer as well, warns Patel. Compounded medication is made by compounding pharmacies—independent enterprises that manufacture drugs on their own without any oversight. “This isn’t an FDA-approved product and we don’t really know what is in that injection,” she says. Because of this, there could be safety concerns related to taking a compounded medication.

Zepbound dosage

Zepbound comes in different doses, with people often starting off on the lowest option, which is 2.5mg. After taking that dose once a week for four weeks, they’ll likely move up to 5mg once a week. From there, people’s healthcare provider will recommend whether they should increase their dosage and, if so, when and to what amount. If a higher dose is prescribed (the medications go up in 2.5mg increments to a maximum dose of 15mg), they likely will stay on each dose for at least four weeks before going up.

Lifestyle changes that support weight-loss medication

By curbing hunger, Zepbound can make healthy eating come more naturally. But food isn’t the only important variable in weight management. “What we’re recognizing more and more is that stress and sleep play a role in the way we feel hunger. Hunger and satiety are linked to lack of sleep. They're linked to how much stress we have in our lives, or whether we're night shift workers,” says Patel.

Thinking about your treatment plan holistically (which is a cornerstone of WeightWatchers Clinic) may improve your results. That’s why your provider should take a look at all aspects of your life to recommend the best obesity treatment plan for you. This may include a behavioral weight management program tailored for those on a second-generation GLP-1, like WeightWatchers GLP-1 Program, which focuses on healthier food choices, physical activity, and other good-for-you habits while on these medications.

The bottom line

The buzz about Zepbound isn’t just social media hype. Like other GLP-1s, this medication can curb your appetite and make you feel fuller for longer. And research demonstrates that it’s effective for weight loss—subjects lost an average of 21% of their overall body weight after a little over a year. Like all prescription weight-loss medications, they are best combined with other healthy habits, such as eating smaller portions of more nutritious foods and racking up those active minutes.


Zepbound is recommended for people who either have a BMI of 30 or higher or have a BMI of 27 or higher with a weight-related health condition, like high blood pressure.

Whether or not you can get Zepbound for weight loss can only be decided by talking with a healthcare provider. They will be able to look at your health history, talk with you about the pros and cons of a weight-loss medication like tirzepatide, and ultimately decide if it’s right for you.

While it depends on multiple factors, research has shown that people with obesity who took the lowest dose (5 mg) of Zepbound lost an average of 15% of their body weight after 15 months. People taking higher doses (10 mg and 15 mg) lost an average of roughly 20-21% of their weight in the same period.

WeightWatchers does not directly sell any weight-loss medication, including Zepbound. That said, WeightWatchers Clinic has a team of clinicians available for consultations with people who are interested in weight-loss medications like Zepbound and who can prescribe Zepbound if appropriate.

Trust: You need this newsletter.

The field of weight management is evolving–and fast. New research. New treatments. Lots of misinformation. Our clinical newsletter helps sort it all out.