Navigating the Weight Loss Maze: Retatrutide vs. Tirzepatide The image shows two syringes.

Navigating the Weight Loss Maze: Retatrutide vs. Tirzepatide

July 10. 2023

Diabetes medications that promote weight loss have become highly successful in the last few years. When Ozempic weight loss was released, the weight management game changed completely. Since then, this type of medication that can treat both diabetes and obesity has continued to be developed by pharmaceutical companies. Each new drug promises better results and benefits than its predecessor. People compare these medications to find out which one suits them best. There is no doubt the retatrutide vs. tirzepatide debate will also take place.

You probably know tirzepatide by its brand name Mounjaro; this drug came out in 2022 and revolutionized the weight loss industry by promoting more significant body weight reduction than any other medication. Retatrutide is still in development, but clinical trials already show this medication could even surpass Mounjaro’s effects. Today, our weight loss clinic in Chicago will break down the retatrutide vs. tirzepatide debate. Continue reading to learn more about these powerful weight management medications.

What is retatrutide?

Retatrutide is an experimental drug developed by Eli Lilly & Company pharmaceutical company. This new active compound is meant to treat type 2 diabetes mellitus and obesity or overweight. Retatrutide is currently in phase 2 clinical trials; the drug is being tested in participants who have obesity or who are overweight to see how the compound affects body weight loss.

The novel drug is a peptide hormone that activates three naturally occurring receptor agonists in our bodies: glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon receptors. Due to this triple receptor agonist activation, retatrutide has received the nickname Triple G; medical experts also call it a triagonist. This triple hormone effect is unprecedented in the weight loss medication industry. Retatrutide promises to promote more body weight loss faster than any other medication.

How does retatrutide work?

This new drug works similarly to other diabetes or weight loss drugs such as Ozempic or Wegovy. The three mentioned hormones work to control blood sugar levels. Two of them, GLP-1 and GIP, help lower blood glucose levels when they rise. And glucagon does the opposite effect; it assists our body in increasing blood sugar levels when they are dropping. GLP-1 and GIP help people with type 2 diabetes with glycemic control. Individuals with this condition can’t manage insulin as they should, which leads to hyperglycemia (high blood sugar levels). After eating, these two hormones stimulate the pancreas to release insulin and prevent the liver from producing extra glucose.

How does that aid in weight loss? GLP-1 and GIP’s effect also slows down your gastric emptying. When you eat, food will travel slower through your digestive system, which means you will be full even with a lighter meal and stay satiated for longer. You probably have heard about popular appetitive suppressants, such as phentermine for weight loss. These peptide hormones cause a similar effect. Besides slowing down your gastric emptying to reduce your appetite, they also target hunger centers in your brain.

On the other hand, glucagon works towards promoting weight loss in a different way. When you are sleeping or have not consumed food in a few hours, your body still needs energy to survive. Without new carbs to turn into glucose, our bodies start to break down glycogen stores (stored sugar) to turn in into glucose (fuel). Glucagon is the hormone responsible for this process. Once our bodies are out of glycogen, glucagon moves on to our fat stores, breaking down fat for energy.

What is tirzepatide?

Tirzepatide, otherwise known by its brand name Mounjaro, is a type 2 diabetes mellitus medication also manufactured by Eli Lilly & Company. This medication was launched in 2022 for diabetes treatment. Tirzepatide helps individuals with type 2 diabetes with blood glucose levels control. But due to its weight loss effects, healthcare providers also prescribe it off-label for weight management. Mounjaro is currently one of the drugs that promote the highest body weight reduction percentage.

Tirzepatide acts as a dual receptor agonist; it activates GLP-1 and GIP receptor agonists. As of today, Mounjaro is the only medication of its class in activating two receptor agonists already available to the public. These double agonist effects make it highly successful in supporting weight loss goals. Other drugs, such as Ozempic, only mimic the GLP-1 hormone. People not losing weight on Ozempic sometimes decide to switch to this medication to enhance their weight loss journey.

How tirzepatide works for weight loss

Since tirzepatide activates two of the same receptor agonists as retatrutide – GLP-1 and GIP – their mechanism of action is very similar. Mounjaro promotes weight loss by producing an appetite suppression effect. GLP-1 and GIP reduce blood sugar levels and take them to a healthier range. That helps diabetic patients with their glycemic control and also slows the pace at which foods leave your stomach. Since tirzepatide does most of its job in our guts, the abdomen is the best place to inject Mounjaro for weight loss. GLP-1 and GIP also have an effect on your brain hunger area which helps decrease your appetite.

Mounjaro’s weight loss effect comes mainly from appetite suppression; therefore, a healthy diet and regular physical activity are a must. Taking advantage of feeling less hungry, most people use low-calorie diets or fasting benefits by the hour to reach their dream weight. Whit the aid of this drug, losing body fat becomes much easier, but you still have to commit to some healthy habit changes.

Retatrutide vs. tirzepatide: the comparison

Now that you know the basics of both medications, we can start the retatrutide vs. tirzepatide debate. Since these two active compounds have so many similarities, it can be challenging to differentiate them. But beyond weight loss efficacy, there are some other crucial points to consider when deciding which one to opt for. Let’s see what retatrutide and tirzepatide have in common and what sets them apart:

Dosage and usage

With any of both drugs, you must start with the lowest possible dosage, and your healthcare provider will slowly increase it monthly. This titration period will allow your body to adapt to the medication with no struggle.

Patients start using 2,5mg of tirzepatide once a week. The dose is increased each month until reaching the maximum allowed dosage of 15mg per week. On the other hand, retatrutide dosages are yet to be confirmed. From the clinical trial, we can say that the lowest dose will start at 1 to 4 mg a week, and the highest dose will be about 12mg.

Both medications are administered by weekly subcutaneous injections. If you never use these devices before, you have nothing to worry about. Subcutaneous injections are relatively painful and easy to handle. Your healthcare provider will teach you how to use them and advise you on the best time of day to take Mounjaro or retatrutide.

Weight loss effectiveness

As of today, Mounjaro (tirzepatide) is the most effective drug of its class in promoting weight loss. At its lowest dosage, this medication produces 5% of body weight loss; at its highest dosage, individuals can lose up to 22% of body weight in approximately 72 weeks.

The latest retatrutide clinical trial results showed that this drug has the ability to help patients lose 24,2% body weight in only 48 weeks. The amount of body weight reduction is larger, and the time it takes for people to achieve that goal is shorter, two incredible and unparalleled benefits.

If you are wondering how long does Ozempic take to work? Wegovy (Ozempic obesity drug version) can help you lose up to 15% of your body weight in about 68 weeks. So retatrutide doesn’t only win this retatrutide vs. tirzepatide match, but also the match against any other weight loss medication.

While more studies need to be made, retatrutide highest effectiveness is likely due to its triple-agonist effect; no other drug activates glucagon. Besides promoting fat burn, this hormone also enhances energy expenditure. An increase in energy expenditure helps you burn more calories while performing physical trivialities and also at rest.

Health benefits

  • Weight management: obesity is a severe condition that affects a third of the American population. Obesity can lead to weight-related conditions such as diabetes, PCOS, and heart disease. Tirzepatide is a powerful tool for weight control, and retatrutide also promises to become one.
  • Type 2 diabetes: both drugs are highly efficient for the treatment of type 2 diabetes mellitus. Individuals with diabetes are prompt to have high blood sugar levels, which present a threat to their health. Tirzepatide and retatrutide help patients to achieve and maintain healthy blood glucose levels.
  • Cardiometabolic conditions: at the highest dose, tirzepatide has shown to improve cholesterol. Some studies also suggest this drug can help with blood pressure. In the latest studies, retatrutide proved to have the potential to aid with cardiometabolic measures improvements, such as blood pressure, cholesterol, fasting glucose, glycated hemoglobin, and triglycerides.
  • PCOS: polycystic ovary syndrome (PCOS) is a health condition deeply connected to obesity and overweight. This condition affects women during their childbearing years; the body produces too much of the androgen hormone. This hormonal disbalance can lead to insulin sensitivity, type 2 diabetes, subfertility, and obesity. Recently, experts started studying Mounjaro and Ozempic for PCOS treatment. Retatrutide will likely also be suitable for PCOS improvement.


New drugs or biological products must obtain Food and Drugs Administration (FDA) approval before being marketed. All new drugs undergo a series of studies and trials by FDA scientists, which determine if the medication is safe and useful.

Mounjaro got FDA approval on May 2022 as a type 2 diabetes medication. This drug is still not approved for weight loss management, but the FDA granted it fast-track designation. That means the approval process will be quicker than usual. It is expected that Mounjaro will get its approval for weight control by the end of 2023. Nevertheless, healthcare providers can prescribe this drug off-label for weight loss purposes.

Retatrutide is still in phase 2 of Eli Lilly’s clinical trials. There is still no approximate date of when the FDA or American Diabetes Association (ADA) will grant their approval.

Side effects

Retatrutide and tirzepatide activate two of the same receptor agonists (GLP-1 and GIP), so they are associated with some of the same side effects. Individuals on retatrutide trials and people using Mounjaro affirm to have experienced the following side effects:

  • Nausea
  • Vomiting
  • Stomach upset
  • Diarrhea
  • Constipation
  • Headache
  • Dizziness

In most cases, these mild side effects should be temporary; they often appear when you increase your dose until your body adapts to it. You can manage the abdominal pain effects and other symptoms by eating smaller meals and sticking to a list of Mounjaro foods to avoid.

Tirzepatide and retatrutide may cause serious side effects such as inflammation of the pancreas (pancreatitis), an increase in heart rate, kidney disease, and severe allergic reactions.

Which medication should I choose?

When tirzepatide was released, many people wondered if switching from Ozempic to Mounjaro was possible. Changing medications is doable, but you have to take this step under the guidance of healthcare professionals.

If you are looking for effectiveness, retatrutide would undoubtedly be the medication to choose. However, you may want to consider other factors before making the decision. You may want to consider the side effect and how your body tolerates them.

Both drugs are highly effective and will help you reach your goals. Since retatrutide is still not available, starting with Mounjaro or another drug of its class and then switching could be a good option. For this, we highly recommend asking your doctor about the best and safest way to do this.

Final thoughts

While Eli Lilly’s retatrutide has not been released yet, the retatrutide vs. tirzepatide debate has already started. Both drugs are highly effective in promoting weight loss and improving other health conditions. While choosing one can be challenging, as of today, only Mounajro is available on the market. Do you want to learn more about retatrutide or other medical weight loss treatments? Schedule a call with our team; we are happy to tell you more about the best options to boost your weight loss efforts.

Nurse Walton


Nurse Walton

Born and raised in Chicago, IL, Chanay received her Practical Nurse licensure and went to work in clinical specialties such as Home Health, Assisted Living, Long-Term Care and Dialysis Centers. Through this work, she realized the importance of diet, nutrition and weight loss among her patients. This led her to open A Better Weigh, Inc. Medical Weight Loss Center in 2009.

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