Written by Joshua Murdock, PharmD, BCBBS | Reviewed by Alyssa Billingsley, PharmD Updated on January 9, 2023
Key takeaways:
- Tirzepatide, the active ingredient in Mounjaro, is being studied in two phase 3 trials for weight loss. In one study, participants lost an average of 15% to 20% of their initial body weight.
- There are other promising weight loss treatments currently in the works. Oral semaglutide and CagriSema are in phase 3 clinical trials, and there are many more medications in phase 2 trials.
- Several medications are already FDA-approved for weight loss. Wegovy (semaglutide), Saxenda (liraglutide), and Contrave (naltrexone/bupropion) are common examples.
Mykola Sosiukin/iStock via Getty Images Plus
There’s not a body out there that’s better than your own. It’s the vehicle that takes you through life. And no matter what size, shape, or height it is, there are countless reasons to be proud of it.
Still, some internal or external factors may be driving you to try to lower your body weight. Perhaps, it’s wanting to improve your body image. Or maybe it’s related to a health issue your provider warned you about. Regardless, there are steps you can take to help you meet your health goals.
When possible, a healthy diet and exercise are ideal ways to lose body weight. But, if needed, medication is another way to help promote weight loss. While there are multiple weight loss medications already on the market, there are several promising treatments currently in clinical trials.Promotion disclosureinfo_outlined
What is the newest weight loss drug in development?
Among the weight loss medications now being studied in clinical trials, tirzepatide appears to be the furthest along.
Tirzepatide (Mounjaro) is a weekly injectable medication that’s currently approved to treat Type 2 diabetes in adults. But the manufacturer, Eli Lilly, is seeking its approval as a weight loss treatment as well. What’s more, the initial data appears positive.
In a recent phase 3 clinical trial, over 2,500 adults living with obesity or overweight lost about 15% to 20% of their starting body weight after taking tirzepatide for 16 months. Another phase 3 trial is expected to wrap up by April 2023. The FDA will review this data in an expedited manner, so there’s a chance tirzepatide could be approved for weight loss sometime in 2023.
Taking tirzepatide for weight loss is discussed in detail in this recent GoodRx Health article.
How does tirzepatide work for weight loss?
Tirzepatide mimics two hormones in your body: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). It’s the first medication that targets receptors (chemical binding sites) for both of these hormones. This helps you eat less and feel full for longer.
Tirzepatide works in a way that’s comparable to Wegovy, an injectable medication that’s currently approved for weight loss. But Wegovy’s active ingredient, semaglutide, only targets GLP-1 receptors, not GIP receptors.
What other weight loss drugs are being studied in clinical trials?
Tirzepatide aside, many other weight loss drugs are working their way through clinical trials. Some are enrolled in phase 3 studies, while others are in phase 2 studies. In general, successfully completing a phase 3 clinical trial is the last step before a medication can be submitted for FDA approval.
Oral semaglutide
Semaglutide is currently available in the form of three FDA-approved, brand-name products: Ozempic, Rybelsus, and Wegovy. Ozempic, an injectable medication, and Rybelsus, an oral tablet, are both approved to treat Type 2 diabetes. However, semaglutide in its oral form is now being studied for weight loss in a phase 3 study called OASIS 1.
Interim results from the OASIS 1 trial are yet to be released. But current evidence suggests that oral semaglutide may offer more weight loss benefits than medications like liraglutide.
The OASIS 1 trial is scheduled to run through May 2023. If all goes to plan, oral semaglutide may eventually become an injection-free alternative to Wegovy.
CagriSema
CagriSema is a combination treatment that combines two injectable medications (cagrilintide and semaglutide) into one therapy. Cagrilintide mimics a hormone called amylin, which helps you feel more full after meals. As mentioned above, semaglutide mimics GLP-1.
A phase 3 study of CagriSema in weight loss just started in November 2022. It’s scheduled to run until October 2026. We’ll learn more about the medication’s effectiveness as the trial goes on.
Ecnoglutide
Ecnoglutide (XW003) is a study medication that’s injected under the skin once weekly. It’s a GLP-1 agonist that’s thought to be a longer-lasting alternative to medications like liraglutide.
Interim results from a phase 2 study comparing ecnoglutide to liraglutide found that, after about 4 months, ecnoglutide helped people lose slightly more weight. The full study results should be available by mid-2023.
If injections aren’t for you, an oral version of ecnoglutide is currently being studied in a phase 1 trial.
Mazdutide
Mazdutide (IBI362) is a once-weekly, under-the-skin injection. It’s a GLP-1 agonist, similar to Wegovy and Saxenda. But it also promotes weight loss by mimicking a hormone called glucagon.
So far, results for a phase 2 study show that mazdutide promotes weight loss more than a placebo. After about 6 months, people receiving mazdutide lost about 8% to 13% more of their body weight than those given the placebo. This China-based study is scheduled to run until September 2023. What’s more, a phase 3 study for weight loss recently began in China.
Retatrutide
Retatrutide (LY3437943) is another study medication that’s injected under the skin once weekly. Like tirzepatide, it mimics GIP and GLP-1. But it also mimics glucagon.
Animal studies suggest that this three-prong approach could lead to more weight loss than with tirzepatide. Early data from a recent phase 2 trial in humans had similar findings. Eli Lilly, the manufacturer of retatrutide, estimates that the medication may help people lose up to 24% of their initial body weight after 48 weeks (11 months). A more advanced phase 3 study is set to launch in 2023.
ARD-101
ARD-101 is a twice-daily oral pill. It targets “bitter taste receptors” throughout your gut to help regulate your appetite. Despite being called a bitter taste receptor agonist, ARD-101 is not designed to affect your sense of taste.
ARD-101’s initial phase 2 obesity study is expected to be completed by December 2022. Two more phase 2 studies should be completed by May 2023.
NNC0165-1875
NNC0165-1875 (PYY 1875) is another once-weekly injection that’s given under the skin. It’s thought to lower your appetite by mimicking the gut hormone pancreatic peptide YY (PYY).
Because of the unique way it works, NNC0165-1875 is being studied as a possible add-on treatment to Wegovy. Its phase 2 trial was expected to conclude by November 2022, but results aren’t available yet.
Other medications
In addition to the above list, there are a few notable medications to keep in mind that are currently being studied as weight loss treatments:
- Orforglipron: Also being developed by Eli Lilly, orforglipron (LY3502970) is an oral medication that mimics GLP-1. Interim data from a phase 2 trial suggests that it may help people lose up to 15% of their body weight after 36 weeks (8 months). A phase 3 study is on deck for 2023.
- MBL949: A medication being developed by Novartis, MBL949’s phase 2 weight loss trial is scheduled to run through March 2023. Not much is known about how it works.
- Nabilone: Currently approved as an anti-nausea medication, this cannabis cousin is enrolled in a phase 2 weight loss trial that should be completed by May 2023.
What medications are already FDA-approved for weight loss?
As of November 2022, 10 medications are FDA-approved as weight loss treatments. Some are only meant for short-term use, while others can be used for weight management over time.
| Medication | Dosage form | How it works |
|---|---|---|
| Contrave (naltrexone/bupropion) | Tablet | Lowers appetite |
| Qsymia (phentermine/topiramate ER) | Capsule | Lowers appetite, helps you feel full |
| Orlistat (Alli, Xenical) | Capsule | Blocks fat absorption from your diet |
| Phentermine (Adipex-P, Lomaira)* | Tablet or capsule | Lowers appetite |
| Phendimetrazine* | Tablet or capsule | Lowers appetite |
| Diethylpropion* | Tablet | Lowers appetite |
| Benzphetamine* | Tablet | Lowers appetite |
| Wegovy (semaglutide) | Injection | Lowers appetite and food intake |
| Saxenda (liraglutide) | Injection | Lowers appetite and food intake |
| Imcivree (setmelanotide) | Injection | Used only to treat certain genetic conditions, lowers appetite, increases energy use |
*Only meant for short-term use
Are there medications that are used off-label for weight loss?
Yes, there are many medications that are prescribed off-label for weight loss. In most cases, they’re prescribed because they cause weight loss as a side effect. These are some top examples:
- Metformin
- Tirzepatide
- Trulicity (dulaglutide)
- Ozempic (semaglutide)
- Pramlintide (Symlin)
- Topiramate (Topamax)
- Bupropion (Wellbutrin SR, Wellbutrin XL)
- Zonisamide (Zonegran)
Note: You should never take medication for weight loss purposes without talking to your healthcare provider first. Many of these medications have risks and side effects to keep in mind.
GoodRx Health
What is the best weight loss drug?
The “best” weight loss drug for you depends on your preferences, body weight goals, and medical history. The amount of time you’re looking to take weight loss medication is also a factor, as is cost.
For instance, Wegovy is a popular once-weekly injectable option. It often helps people lose more weight over time than other weight loss medications. But Wegovy’s side effects, which include nausea and diarrhea, can be bothersome for some people.
Since weight loss medications have a lot of variability, it’s important to make an informed decision about which medication to try. Your healthcare provider can help you narrow down your options.
The bottom line
Making dietary and lifestyle changes is an important first step for long-term weight management. But sometimes a medication may be added to help you reach your goals. Wegovy (semaglutide), Saxenda (liraglutide), and Contrave (naltrexone/bupropion) are common choices. But there are several other options, both on the market and making their way through clinical studies — tirzepatide being perhaps the most promising.
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