Weight Loss Injections Part 2: Mounjaro® (Tirzepatide)

by Brenda Hoehn on Aug 23, 2023

Weight Loss Injections Part 2: Mounjaro® (Tirzepatide)

Weight Loss Injections Part 2: Mounjaro® (Tirzepatide)


Mounjaro® is a once-a-week injection that the FDA approved to treat type 2 diabetes in May 2022.


The medication’s official website states that the drug regulates blood sugar and decreases food intake.

It also states that Mounjaro® is NOT a weight loss drug, despite its ability to reduce one’s body weight by as much as 20%, a statistic comparable to bariatric surgery results.

Protocol dictates that patients follow a dosing schedule with six different dosages, ranging from 2.5mg/0.5ml to 15mg/0.5ml.

Please view the brand’s official “Medication Guide” for more extensive information regarding patient use.


As mentioned in the first part of this series, GLP-1 and GIP are incretin hormones the body releases after a meal.

*Links to the rest of this series are available at the bottom of this page.

Tirzepatide (Mounjaro®) is unique because it is the first (and only) FDA-approved GLP-1 and GIP receptor agonist medication (a “twincertin”). The GLP-1 and GIP receptor agonist is a single molecule that targets the body’s receptors for naturally occurring GLP-1 and GIP hormones.

Mounjaro® mimics the incretin effect, albeit prolonging the period the incretin effect influences the body, enhancing the GLP-1 and GIP benefits regarding glycemic control and weight management.

Tirzepatide & Type 2 Diabetes

The “SURPASS-5 Randomized Clinical Trial” looks at the effects of tirzepatide on glycemic control by observing patients’ HbA1C at 5 mg, 10 mg, and 15 mg doses versus placebo before, during, and at the end of 40 weeks.

The overall average baseline HbA1C level at the start of the trial was 8.31%.

Researchers used data collected at 40 weeks to calculate the percentage of patients from each group with an average HbA1C below 7%, 6.5%, and 5.7%.

The overall average percentage of patients from all tirzepatide groups compared to the placebo group is as follows:

  • HbA1C levels below 7%
    • Tirzepatide – 94.8%
    • Placebo – 33.9%
  • HbA1C levels below 6.5%
    • Tirzepatide – 89%
    • Placebo – 17%
  • HbA1C levels below 5.7%
    • Tirzepatide – 45.4%
    • Placebo – 2.5%

For more detailed graphics and interpretations of the data in this trial, please view its “Supplemental eAppendix.”

Tirzepatide & Weight Loss

A 2022 trial tests the efficacy of tirzepatide in treating obesity in patients by observing and comparing three tirzepatide groups (5 mg, 10 mg, and 15 mg) and a placebo group with once-weekly medication administration for 72 weeks.

The significant baseline measurements encompassing all patients include the following:

  • Average Body Weight – 231 lbs
  • Average BMI – 38.0
  • Patients with a BMI>30 (%) – 94.5%

The average percentage of lost body weight at week 72 was:

  • Tirzepatide
    • 5 mg: -16% (35.5 lbs.)
    • 10 mg: -21.4% (48.9 lbs.)
    • 15 mg: -22.5% (52 lbs.)
  • Placebo: -2.4% (5.3 lbs)

Overall, the overall ending average body weight of the tirzepatide patients compared to the placebo patients was:

  • Tirzepatide – 185.5 lbs
    • Baseline – 231 lbs
  • Placebo – 225.8 lbs
    • Baseline – 231lbs

For additional statistics, graphics, and supplemental information on the trial’s parameters, please view its “Supplementary Appendix.”

Side Effects

The most common tirzepatide side effects are gastrointestinal in nature, such as:

Serious side effects:

  • Thyroid Tumors
  • Allergic Reaction
  • Gallbladder Disease:
  • Pancreatitis
  • Kidney Damage
  • Liver Damage
  • Fainting
  • Dizziness

Additional side effects:

  • Decreased Appetite
  • Back Pain
  • Arthralgia (Stiff Joints)
  • Hypoglycemia
  • Hyperglycemia
  • Injection Site: Rash or Redness

Please follow the link for the Mounjaro® “Medication Guide” (available at the top of the blog) for more information specific to the brand.

Our “Weight Loss Injections” Series Contributor

ProCare Health would like to recognize award-winning Dietitian and Nutritionist Katie Chapmon as a contributor to this comprehensive series on the various medications bariatric patients may want to discuss with their doctors.

With over ten years of hands-on clinical experience in bariatric surgery and weight management, Chapmon’s wealth of educational and reliable information is valuable for the patients that use our resources to navigate pre-and post-bariatric surgery life.

ProCare Health’s “Weight Loss Injections” Series

So far, we’ve covered the information provided in this blog post and an overview filled with insightful information on the health conditions the medications in this series treat.

The following two parts of this series will cover semaglutide’s and liraglutide’s efficacy for type 2 diabetes and weight management.

To view the other blogs in this series, you may use the following links:

For more informational bariatric resources and premium bariatric vitamins and supplements, please visit