In the ever evolving field of weight management, two recently marketed drugs have captured significant attention: Wegovy (semaglutide) and Zepbound (tirzepatide). While originally designed to address type 2 diabetes, both medications demonstrated impressive results in overweight individuals who do not have type 2 diabetes. This post will explore what current clinical trial data tells us about their efficacy in weight loss and their side effect profiles.
Weight Loss Outcomes
Both Wegovy and Zepbound were studied extensively in non‑diabetic populations. The pivotal STEP trials evaluated Wegovy’s effectiveness over approximately 68 weeks, while the SURMOUNT‑1 trial assessed the impact of Zepbound over a similar period. Although these results come from separate studies, looking at the trends can help understand how these treatments compare.
The table below summarizes the observed weight loss at various time points:
| Time Point |
Wegovy (Semaglutide 2.4 mg) |
Zepbound (Tirzepatide, highest effective dose) |
| Week 16 |
~8% reduction in body weight |
~10% reduction in body weight |
| Week 32 |
~11% reduction in body weight |
~14% reduction in body weight |
| Week 52 |
~13–14% reduction in body weight |
~17% reduction in body weight |
| Final Endpoint |
~15% reduction at ~68 weeks |
~20% reduction at ~72 weeks |
Interpreting the Data
As shown in the table above, both medications promote significant weight loss throughout the study periods.
- Wegovy: Patients typically experience a steady reduction in body weight, reaching around a 15% decrease by the end of the treatment period.
- Zepbound: With tirzepatide, the weight loss effect is dose‑dependent, with the highest doses offering approximately a 20% reduction, indicating a potentially more robust performance in terms of weight reduction.
These differences may help guide individualized treatment choices for patients who want to achieve greater weight loss over similar time frames.
Our experience at BeLite shows that a significant number of patients achieve what can only be called “amazing” weight loss, such as a person with a BMI of 35 losing to a BMI of 23.
Gastrointestinal Side Effects
While both drugs are effective at weight loss, their gastrointestinal (GI) side effects also play a crucial role in treatment tolerability. Here’s how the two compare based on the clinical trials noted above:
| Adverse Event |
Wegovy (Semaglutide 2.4 mg) |
Zepbound (Tirzepatide, Obesity Population) |
| Any GI adverse event |
~40–45% |
~50–60% |
| Nausea |
~20–30% |
~25–35% |
| Diarrhea |
~10–20% |
~15–25% |
| Vomiting |
~5–15% |
~10–20% |
| Discontinuation due to GI AEs |
~3–5% |
~5–7% |
Balancing Efficacy and Tolerability
The tables above highlight a common theme in weight management therapies using these injectable medications: achieving optimal weight loss comes with an increased incidence of GI side effects.
We note that many patients acclimate to the medications and the the GI side effects diminish or stop.
- Wegovy: Patients typically experience GI events that are mostly mild to moderate, with the majority reporting nausea as the primary complaint. The discontinuation rate due to such side effects tends to be low. As noted, we observe at BeLite that many patients have no GI side effects, or that they tend to fade with time.
- Zepbound: Tirzepatide’s weight loss benefits are accompanied by a slightly higher incidence of GI events. The dose‑dependency suggests that while higher doses may yield greater weight loss (up to ~20%), they are also more likely to cause side effects like nausea, diarrhea, and vomiting.
Its important to realize that the reported percent of patients with particular side effects are averages with a wide margin of error – so they do not predict what any one individual will experience.
Clinicians must weigh these factors when discussing treatment options with patients. In practice, the choice between these therapies will depend on individual preferences, tolerance, and overall health profiles.
Final Considerations
Both Wegovy and Zepbound represent significant advances in the treatment of obesity in non‑diabetic patients. While Zepbound may offer, on average, a greater percentage of weight loss, it also comes with a higher rate of gastrointestinal side effects compared to Wegovy. For many patients, the decision will boil down to personal tolerance for side effects versus the desire for rapid or more substantial weight loss.
Ultimately, these therapies provide new hope and options for patients struggling with obesity. As always, treatment decisions should be made in close consultation with healthcare professionals, experienced with treating obesity with medications, who can tailor options to the unique needs of each patient. The Medical Providers at BELITE are experts at weight loss medications and have helped thousands of patients achieve their weight loss goals.
Disclaimer: The data presented in this blog post are approximations derived from published clinical trial summaries. They are intended for informational purposes only and should not be considered medical advice. Please consult a healthcare professional for guidance tailored to your personal health condition.
BeLite can help patients translate emerging obesity-medicine evidence into an individualized plan that considers efficacy, tolerability, nutrition, muscle preservation, long-term maintenance, and access.BeLite Medical Center has provided physician-supervised medical weight management in Fairfax, Virginia since 1995. Our clinic offers in-person medical supervision — with the ability to adjust medications and monitor your progress in real time — that fully virtual services cannot match.Booking appointments is simple with our online scheduling portal, available 24/7. You can also call or text us at (703) 359-9200, or email belitemed@gmail.com. We offer free consultations for new patients — if you choose not to enroll, there is no charge. We serve patients across Virginia, Maryland, Washington D.C., the DMV area, Pennsylvania, and West Virginia. Patients do not sign treatment contracts and can stop coming at any time
Medical Disclaimer
This blog post is provided for informational purposes only and does not constitute medical advice, diagnosis, or treatment. It is not intended to substitute for consultation with a licensed healthcare provider. Readers should not use this information to diagnose or treat a medical or health condition without consulting an appropriately qualified healthcare professional. Any reliance on the information in this blog is at the readers own risk. Individual weight loss results vary based on personal health status and adherence to medical advice. No doctor-patient relationship is created by accessing or reading this content.
Reviewed by Richard Rothman, MD, PhD — Medical Director, BeLite Medical Center.
About Richard B Rothman MD, PhD, Medical Director, BeLite Medical Center
Dr. Rothman is the Medical Director of BeLite Medical Center, which has been helping patients lose weight in the Northern Virginia area since 1996. Board certified in Psychiatry, Dr. Rothman earned his M.D. and Ph.D. in Pharmacology from the University of Virginia in 1982.
