GLP-1 Medications for Weight Loss Compared: Zepbound, Wegovy, Mounjaro, and Ozempic

I hear the same four names in my office almost every week, usually in the same confused order: “Isn’t Ozempic the same as Wegovy? Is Mounjaro just a generic version of Zepbound? Which one should I be on?” Patients arrive having read about all four online, sometimes convinced they’re four separate drugs, sometimes convinced they’re all interchangeable. Neither is quite right, and untangling it is one of the most useful conversations I have with patients considering medical weight loss.

As a board-certified Internal Medicine physician in Plano, TX, I prescribe and manage these medications directly. Here’s the full picture: what each drug actually is, what it’s approved for, what the trials showed, and where coverage stands right now.

Same Molecule, Different Name, Different Job

This is the single most important thing to understand before comparing any efficacy numbers, because two of these “four” medications are really the same medication marketed twice.

Semaglutide: Ozempic and Wegovy

Semaglutide is one drug. Ozempic and Wegovy are both semaglutide, from the same manufacturer, but they’re approved for different uses at different doses. Ozempic is FDA-approved for type 2 diabetes, dosed up to 2mg. Wegovy is FDA-approved for chronic weight management, dosed at 2.4mg. Same molecule, different approved use, different top dose.

Tirzepatide: Mounjaro and Zepbound

The same pattern holds for tirzepatide. Mounjaro is FDA-approved for type 2 diabetes. Zepbound is FDA-approved for chronic weight management. They’re the same active drug marketed under two names for two different indications.

Why does this matter beyond terminology? Because a medication’s FDA-approved indication determines which trials it was actually studied in, and that determines what I can honestly tell you to expect from it. That’s the next piece.

What the Weight-Loss-Approved Medications Showed in Trials

Zepbound and Wegovy are the two medications actually studied and approved with weight loss as the primary goal, so they’re the two I can compare most directly.

In the SURMOUNT-1 trial, tirzepatide (Zepbound) produced average weight loss over 72 weeks of 15.0% at the 5mg dose, 19.5% at 10mg, and 20.9% at 15mg, compared with 3.1% on placebo (Jastreboff et al., NEJM 2022).

In the STEP-1 trial, semaglutide 2.4mg (Wegovy) produced average weight loss of 14.9% over 68 weeks, compared with 2.4% on placebo, and 86.4% of patients on semaglutide lost at least 5% of their body weight (Wilding et al., NEJM 2021).

A more recent trial, SURMOUNT-5, compared the two medications head-to-head in the same study population: over 72 weeks, tirzepatide produced 20.2% average weight loss versus 13.7% for semaglutide.

I go much deeper into how I actually use these two head-to-head, including who tends to do better on which one, in Tirzepatide vs. Semaglutide: Which Weight Loss Medication Is Right for You? This post is about the bigger landscape.

Why I Can’t Put Mounjaro and Ozempic on the Same Chart

This is where patients get tripped up, and where I have to be careful, because Mounjaro and Ozempic simply weren’t studied as weight-loss drugs.

Mounjaro’s approval rests on the SURPASS program, a set of trials built around blood sugar control in type 2 diabetes. Weight loss was a secondary finding there, not the primary goal, and the amount varied across the trials depending on the specific trial and dose.

Ozempic’s approval rests on the SUSTAIN program, also built around blood sugar control. Those trials reported weight change in kilograms, not percent, and the amount varied across the program. I can’t convert that into a percentage for you, and I won’t line it up next to the Wegovy or Zepbound numbers above, because SUSTAIN measured a different population (people with type 2 diabetes) against a different primary endpoint (blood sugar, with weight as secondary) than STEP-1 and SURMOUNT-1 did. Comparing them directly would be comparing two different questions, not two answers to the same one.

If you’re specifically weighing whether GLP-1 therapy makes sense for you, GLP-1 Weight Loss in Plano, TX: What You Need to Know covers who qualifies and what the process looks like.

Side Effects: What These Medications Can Cause

All four medications share a similar side effect profile, since they work on overlapping hormone pathways.

Common side effects include nausea, diarrhea, vomiting, constipation, abdominal pain, dyspepsia, fatigue, burping, GERD, and injection-site reactions. These are most noticeable early in treatment or after a dose increase, which is a major reason I titrate doses slowly.

Serious risks worth understanding:

A boxed warning for thyroid C-cell tumors, including medullary thyroid carcinoma, based on findings in rodent studies. I want to be precise here: whether this risk applies to humans has not been confirmed, and I’m not going to overstate it. What is clear is that these medications are contraindicated in anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2, and I screen for that history before prescribing.
Pancreatitis
Gallbladder disease — in the Wegovy trials, cholelithiasis (gallstones) occurred in 1.6% of patients versus 0.7% on placebo.
Kidney injury, usually secondary to dehydration from GI side effects like vomiting and diarrhea, which is another reason I check labs and monitor hydration.

Insurance and Medicare Coverage

Coverage is the question I get asked most, and it’s also the one that changes fastest, so I’d rather be straightforward about where things stand than promise something I can’t guarantee.

Coverage commonly hinges on diagnosis: obesity, a BMI of 30 or higher, or a BMI of 27 or higher with a related condition like high blood pressure or high cholesterol, or prediabetes. The American Diabetes Association defines prediabetes as an HbA1c of 5.7% to 6.4%; an HbA1c of 6.5% or higher is in the diabetes range.

The type 2 diabetes-indicated medications, Ozempic and Mounjaro, have long been covered under Medicare Part D for blood sugar control. Wegovy’s cardiovascular risk-reduction indication, approved by the FDA in March 2024, opened Part D coverage for Wegovy specifically for that use. And a new CMS demonstration program, the Medicare GLP-1 Bridge, began on July 1, 2026 and runs through December 31, 2027, extending weight-loss coverage to certain beneficiaries who meet specific BMI and comorbidity criteria. One detail matters here: the Bridge covers a specific list of medications for weight loss — Wegovy, the KwikPen formulation of Zepbound, and Foundayo — and does not cover Ozempic or Mounjaro for that purpose.

That program is new, the rules are still settling, and coverage in general depends entirely on your specific plan, not just your diagnosis. This is why we ask patients to verify their benefits and coverage with their insurance before asking the physician to start the medication, rather than quoting a number in a blog post that may not hold up once your plan actually processes a claim. I’m not going to promise coverage or a cost to anyone here. I’ll tell you, honestly, what your plan says once we check.

For a deeper walkthrough, read Is GLP-1 Weight Loss Medication Covered by Insurance in Texas?

How I Approach This at My Practice

Whichever medication ends up being right for you, the trial numbers above describe groups of study participants, not you individually. Your own results depend on your starting weight, your health history, and how consistently the treatment fits your life.

When a patient and I sit down to choose between these medications, I’m working through:

Your diagnosis and history — diabetes, prediabetes, cardiovascular risk, and anything that would make one option safer or unsafe for you
What you’re actually approved and eligible for, not just what’s trending online
Baseline labs, so we know your kidney, liver, and thyroid status before we start
A dosing plan that starts low and moves up gradually
Ongoing monitoring, with repeat labs and adjustments as you progress

This is also never medication alone. Sustainable weight loss requires a plan built around the prescription, which is exactly what our medical weight management program is designed for.

Getting the right medication starts with an honest look at your history, your goals, and what your plan will actually cover. Schedule a consultation and we’ll sort out the right path together.

Sophia Rahman MD is located at 1212 Coit Rd, Suite 105, Plano, TX 75075. Accepting new patients in Plano, Frisco, McKinney, Allen, Murphy, and the surrounding Collin County area.