Tirzepatide, marketed as Mounjaro for type 2 diabetes and Zepbound for weight loss, is a once-weekly injectable medication that has demonstrated impressive weight loss results in clinical trials. This article provides a comprehensive overview of Zepbound, including its dosage, expected weight loss at different doses, factors influencing weight loss, and potential side effects based on available clinical trial data.
How Tirzepatide Works for Weight Loss
Zepbound (tirzepatide) leads to weight loss by reducing hunger, quieting persistent food thoughts, and promoting a feeling of fullness faster. Tirzepatide mimics two hormones in the body, GLP-1 and GIP, which help regulate blood sugar levels and promote weight loss. These hormones stimulate insulin secretion, slow down the movement of food through the stomach, and reduce the production of glucagon by the liver.
Zepbound Dosage Guide
Zepbound is available as an injector pen for once-weekly subcutaneous injections. It comes in the following doses:
- 2. 5 mg
- 5 mg
- 6. 5 mg
- 10 mg
- 5 mg
- 15 mg
The 2.5 mg and 5 mg vials are also available as single-dose vials.
A typical Zepbound dosage chart involves a gradual increase in dosage to minimize side effects and allow the body to adjust to the medication. A sample dosage chart is as follows:
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- Weeks 1-4 (Month 1): 2.5 mg
- Weeks 5-8 (Month 2): 5 mg
- Weeks 9-12 (Month 3): 7.5 mg
- Weeks 13+ (Month 4+): 10 mg, 12.5 mg, or 15 mg maintenance dose
It is crucial to start with the 2.5 mg starter dose for four weeks to allow the body to adjust to the medication and minimize the risk of strong side effects. Dosage adjustments should only be made under medical supervision.
Expected Weight Loss on Tirzepatide by Dose
Clinical trials have demonstrated that tirzepatide leads to an average of 15-21% weight loss. In general, higher doses produce greater weight loss results.
On average, tirzepatide weight loss results in just over a year (72 weeks) are:
- 15% weight loss on 5 mg
- 19.5% weight loss on 10 mg
- 20.9% weight loss on 15 mg
For a 200-pound person, this works out to:
- 30 pounds on 5 mg
- 40 pounds on 10 mg
- 42 pounds on 15 mg
In comparison, people who did not take tirzepatide lost only 3.1% of their body weight (about 6 pounds for a 200-pound person).
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Weight Loss on 2.5 mg Zepbound
While tirzepatide begins working immediately, and you may see some initial weight loss on the 2.5 mg dose, it is hard to tell how much to expect since clinical trials do not measure weight loss on the 2.5 mg dose.
Weight Loss on 5 mg Zepbound
People on a 5 mg tirzepatide dose lost an average of about 15% of their body weight over a year, according to a tirzepatide study. This amounts to about 30 pounds for a 200-pound person. 7 out of 10 people on 5 mg tirzepatide experienced a weight loss of 10% or more.
Weight Loss on 10 mg Zepbound
In clinical trials, 9 in 10 people lost more than 5% of their body weight on 10 mg of tirzepatide. More than half lost 20% of their body weight or more. For a 200-pound person, that's about 40 pounds.
Weight Loss on 15 mg Zepbound
In trials, people lost the most weight on the 15 mg dose over a year. Over 90% lost 5% of their body weight or more. Over half of the participants on a 15 mg tirzepatide dose lost 20% of their body weight or more-a 40-pound weight loss for someone weighing 200 pounds in over a year.
Factors Influencing Weight Loss on Tirzepatide
Weight loss results while taking Zepbound depend on factors such as your:
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- individual response to the drug
- initial body weight and body fat percentage
- lifestyle habits
- dose of the medication
Weight loss on tirzepatide is linked to a balanced diet and regular physical activity. Even people in clinical trials had to follow a nutritious, balanced diet and maintain a 500-calorie deficit. They also had to get at least 20 minutes of moderate exercise a day.
Other healthy lifestyle habits that can support weight loss include:
- getting plenty of sleep
- eating adequate fiber
- staying hydrated
- reducing your intake of sugar and highly processed foods
- eating an array of fruits and vegetables
- eating plenty of lean protein
- reducing stress
What to Do If You're Not Losing Weight on Zepbound
While a majority of people on tirzepatide lost weight in clinical trials, a small group of people failed to lose much weight on the medication. Reasons for not losing weight on Zepbound may include:
- Diet and exercise: Ensure you are following a nutritious, balanced diet and maintaining a 500-calorie deficit, along with regular exercise.
- Need a different dose: Consider talking to your healthcare provider if your current tirzepatide dosage is right for you. Please do not adjust your dosage without medical supervision.
- Underlying hormone imbalances: If you're not losing weight on Zepbound, it could be due to other underlying issues. You could talk to your doctor about your concerns, and they may evaluate your thyroid hormones. In females, perimenopause and menopause can lead to weight gain.
Clinical Trial Evidence for Tirzepatide's Effectiveness
A comprehensive search was performed on various databases including PubMed, Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov from inception up to April 29, 2024, to identify randomized controlled trials (RCTs) that assessed the efficacy of once-weekly tirzepatide compared to a placebo in adults with or without T2D. The mean difference (MD) and risk ratio (RR) were calculated for continuous and dichotomous outcomes, respectively. Seven RCTs comprising 4795 individuals ranging from 12 to 72 weeks were identified. Compared to the placebo group, tirzepatide at doses of 5, 10, and 15 mg demonstrated significant dose-dependent weight loss. The mean difference (MD) in the percentage change in body weight (BW) was −8.07% (95% CI −11.01, −5.13; p < 0.00001), −10.79% (95% CI −13.86, −7.71; p < 0.00001), and −11.83% (95% CI −14.52, −9.14; p < 0.00001), respectively. Additionally, the MD in the absolute change in BW was −7.5 kg (95% CI −10.9, −4.1; p < 0.0001), −11.0 kg (95% CI −16.9, −5.2; p = 0.0002), and −11.5 kg (95% CI −16.2, −6.7; p < 0.00001), for the 5, 10, and 15 mg doses, respectively. All three doses of tirzepatide also significantly reduced body mass index and waist circumference. Furthermore, it led to a greater percentage of patients experiencing weight loss exceeding 5, 10, 15, 20, and 25%. Moreover, tirzepatide showed great success in reducing blood pressure, blood sugar levels, and lipid profiles.
Key Findings from the Meta-Analysis
- Weight Loss: Tirzepatide at doses of 5, 10, and 15 mg demonstrated significant dose-dependent weight loss compared to placebo.
- Achievement of Weight Loss Goals: A significantly greater proportion of participants in all tirzepatide dose groups achieved at least 5% weight reduction compared to placebo. Similar findings were observed for achieving weight loss of ≥10% and ≥15%.
- BMI and Waist Circumference: All tirzepatide doses were superior to placebo in terms of change in BMI and waist circumference from baseline.
- Blood Pressure: All tirzepatide doses significantly reduced systolic blood pressure (SBP) and diastolic blood pressure (DBP) compared to placebo.
- Blood Sugar Levels: All three tirzepatide doses were associated with a significant decrease in HbA1c and FPG levels compared to placebo.
- Lipid Profiles: Weekly tirzepatide administration showed a dose-dependent relationship with changes in fasting lipid profiles compared to placebo. All three doses of tirzepatide significantly decreased TC, LDL, VLDL, and triglycerides.
Safety and Side Effects
The most common side effects of Zepbound include nausea, diarrhea, vomiting, constipation, stomach (abdominal) pain, indigestion, injection site reactions, feeling tired, allergic reactions, belching, hair loss, and heartburn. The overall safety profile of tirzepatide in SURMOUNT-4 was similar to previously reported SURMOUNT and SURPASS trials. The most commonly reported adverse events in SURMOUNT-4 were gastrointestinal-related and generally mild to moderate in severity.
Warnings associated with Zepbound include:
- Possible thyroid tumors, including thyroid cancer
- Severe stomach problems
- Kidney problems (kidney failure)
- Gallbladder problems
- Inflammation of the pancreas (pancreatitis)
- Serious allergic reactions
- Low blood sugar (hypoglycemia)
- Changes in vision in patients with type 2 diabetes
- Depression or thoughts of suicide
It is important to discuss any concerns about side effects with your healthcare provider.
Zepbound and Sleep Apnea
Zepbound is also used for weight reduction in adults with obesity, or for severe obstructive sleep apnea in adults who are obese.