Mounjaro versus Wegovy: weight loss, side effects and choosing treatment

How do they help with weight loss?

You can understand them as signals that help the body adjust "whether it is hungry or not, and how much to eat." The ingredient of Mounjaro is tirzepatide, which acts on both GIP and GLP-1 receptors; the ingredient of Wegovy is semaglutide, which acts on the GLP-1 receptor. Both affect appetite and blood sugar, and may also cause the stomach to empty more slowly. What we are talking about here is a course of weekly injections.

How much worse is the weight loss effect? See direct comparison studies

SURMOUNT-5, published in the New England Journal of Medicine in 2025, randomized 751 obese adults without diabetes to compare weekly injections of tirzepatide with semaglutide. At 72 weeks, the mean weight loss was 20.2% versus 13.7%, a difference of 6.5 percentage points. This is a direct comparison from the same trial, which is more convincing than putting numbers from different studies together. [1]

Research figures cannot be directly regarded as personal expected effects

SURMOUNT-5 compared titration to the highest tolerated study dose of tirzepatide 10 or 15 mg weekly and semaglutide 1.7 or 2.4 mg weekly, combined with a diet and activity intervention. This is not an effect of a starting dose of several weeks and cannot be extrapolated to other doses or dosage forms that were not compared.

The study was funded by Eli Lilly and adopted an open-label design. Participants and the research team knew which drug to use; the average results are not guaranteed to be achieved by everyone, nor can they be directly used as predictions for patients with diabetes. [1]

Other important experiments also showed weight loss effects

SURMOUNT-1 (2022) included 2,539 study-eligible overweight or obese adults without diabetes. At 72 weeks, mean weight loss was 15.0%, 19.5%, and 20.9% in the tirzepatide 5, 10, and 15 mg weekly groups, respectively, and 3.1% in the placebo group. [2]

STEP 1 (2021) included 1,961 overweight or obese adults without diabetes; at 68 weeks, the average weight loss was 14.9% in the 2.4 mg weekly semaglutide group versus 2.4% in the placebo group. [3] Both studies were paired with lifestyle intervention, but the groups and designs were different, so 20.9% and 14.9% could not be directly used to compare the effects of the two drugs; the comparison between the two drugs still gave priority to SURMOUNT-5.

Why does BH Clinic choose Mounjaro as his main option?

At BH Clinic, Mounjaro will be evaluated first if he is assessed to be suitable for medical treatment and the primary goal is to pursue greater weight loss. This direction is supported by direct comparative trials, but the actual choice will also consider medical history, comorbidities, side effects, cost and long-term sustainability. Wegovy remains an effective treatment option and may be more appropriate in some cases.

Pursuing better results does not mean blindly increasing the dosage

We hope to improve weight and health as much as possible under the premise of safety, adequate nutrition and body adaptability. During the follow-up visit, we will look at weight trends, waist circumference, food intake, muscle strength and discomfort, and then decide whether to make adjustments. The absence of nausea does not mean that it is ineffective; the inability to eat, persistent vomiting, or obvious weakness are not the therapeutic effects that should be pursued.

The number of milligrams is different and the sizes cannot be compared directly.

The two medicines have different active ingredients. A larger milligram number does not mean a stronger effect. Confirm instructions again when changing medication, changing pen models or restarting after a break. Do not use both medicines together or calculate your own pen-click doses.

Remember to tell your doctor about your medical history first

If you or your family have medullary thyroid cancer, or if you have MEN2 (multiple endocrine neoplasia type 2), be sure to tell them. Any history of severe drug allergies, pancreatitis, gallbladder disease, or severe gastric emptying problems should also be stated. If you are pregnant, planning to become pregnant or breastfeeding, please discuss this before arranging treatment.