Peptides for Weight Loss: What You Need to Know

What Peptides May Promote Weight Loss & How Do They Work?

Prescription peptides are currently FDA-approved to promote weight loss, improve blood sugar control, and/or protect certain patients from cardiovascular events. There are many different peptide medications available and they can be oral drugs like Rybelsus, or injections, like Wegovy, Mounjaro, and Saxenda. Each medication has only one or two intended uses with specific doses. Your doctor will help decide which option is right for you depending on the goals of your treatment.¹

Peptides work in multiple ways in the body to achieve intended results. One way peptides work is through appetite suppression. Peptides also delay gastric emptying time, which can cause a person to feel full sooner and for longer leading to less calorie intake. Over time, appetite suppression and reduced caloric intake may lead to weight loss. Another way peptides work is through improved insulin sensitivity leading to lower levels of glucose in the blood. Peptides have been shown to reduce risks of cardiovascular events but the way this works is not fully understood.^2,3,4,5

Common Types of Prescription Peptides for Weight Loss

There are many peptides currently available by prescription and they vary by name according to each drug’s intended use. There are three brand names for semaglutide: Wegovy (FDA-approved injection for weight loss), Ozempic (FDA-approved injection for diabetes), and Rybelsus (FDA-approved oral tablet for diabetes).

There are two brand names for tirzepatide: Mounjaro (FDA-approved injection for diabetes) and Zepbound (FDA-approved injection for weight loss). Finally there are two brand names for liraglutide: Saxenda (FDA-approved injection for weight loss) and Victoza (FDA-approved injection for diabetes). The decision to choose one over the others will be based on each patient, drug availability, intended uses, and potential price.

• Semaglutide: Semaglutide is currently available as an injection under the name Wegovy (for weight loss) or Ozempic (for type 2 diabetes). Both versions are also indicated for protection of the heart against serious heart issues in certain people. They are administered once weekly and the dose will increase over time until the intended maintenance dose is achieved.^2,3 Semaglutide is also available as an oral tablet called Rybelsus (for type 2 diabetes) and it is not indicated to protect the heart. It is usually taken by mouth once a day.
• Tirzepatide: Tirzepatide is currently available as an injection under the name Zepbound (for weight loss) or Mounjaro (for type 2 diabetes). Neither versions are approved for protection of the heart. They are both administered once weekly and the dose will increase over time until the intended maintenance dose is achieved.^4,5
• Liraglutide: It is currently available as an injection under the name Saxenda (for weight loss) or Victoza (for type 2 diabetes). Only Victoza is indicated for protection of the heart against serious heart issues. Liraglutide is unique as it is administered once daily and the dose will increase over time until the intended maintenance dose is achieved.^6,7

Semaglutide (Wegovy, Ozempic, & Rybelsus)

Semaglutide is available as a prescription injection (Wegovy and Ozempic) or oral pill (Rybelsus). Wegovy is FDA-approved to promote weight loss and maintain weight as well as reduce the risk of major cardiovascular events in certain people. Ozempic is FDA-approved to treat type 2 diabetes and reduce the risk of major cardiovascular events in certain people. Rybelsus is only FDA-approved to treat type 2 diabetes. While Ozempic is sometimes used off label for weight loss, this usage may prevent it from being covered by insurance.^2,3

• How semaglutide works: Semaglutide works through appetite suppression and delayed gastric emptying time, which can cause a person to feel full sooner and for longer leading to less calorie intake. The drug also improves insulin sensitivity and lower levels of glucose in the blood.
• Effectiveness of semaglutide: Multiple studies showed that after more than a year, patients taking Wegovy weekly as prescribed, lost significantly more weight than those given a placebo.² Studies of Ozempic’s effect on blood glucose (A1c) levels, have shown that Ozempic significantly lowers blood glucose compared to placebo and better than many other available diabetes treatments.³
• Side effects of semaglutide:* The most common side effects when taking any form of semaglutide include nausea, vomiting, diarrhea, abdominal pain, and constipation. These effects usually are worse when starting or changing doses and should be monitored if they do not resolve on their own. There is also risk of more serious side effects like thyroid tumors, inflammation of the pancreas, and dangerously low blood glucose levels.^2,3
• What else you should know about semaglutide: Semaglutide should never be combined with any other peptide. Extra caution should be used when any peptide is combined with another antidiabetic drug, especially insulin or insulin secretagogues. Talk with your doctor or pharmacist before you begin treatment to review all other medications you take.^2,3

*All medications, including weight loss medications, can cause side effects which can be mild or serious. This is not a comprehensive list of all possible side effects. You should talk with your doctor about any questions you have and to understand the potential side effects and benefits of any medication.

Tirzepatide (Zepbound & Mounjaro)

Tirzepatide is available as a prescription injection under the names Mounjaro and Zepbound. Zepbound is FDA-approved to promote weight loss and maintain weight. Mounjaro is FDA-approved to treat type 2 diabetes. Neither version of tirzepatide is FDA-approved to reduce the risk of major cardiovascular events. While Mounjaro is sometimes used off label for weight loss, this use may prevent it from being covered by insurance.^4,5

• How tirzepatide works: Tirzepatide works through appetite suppression and delayed gastric emptying time, which can cause a person to feel full sooner and for longer leading to less calorie intake. The drug also improves insulin sensitivity and lowers levels of glucose in the blood. Tirzepatide has a unique structure that causes the drug to last longer in the body and potentially causes even more appetite suppression than other peptides.^4.5
• Effectiveness of tirzepatide: Two studies showed that after more than a year, patients taking Zepbound weekly at prescribed doses, lost significantly more weight than those given a placebo. Studies demonstrated that most patients lost at least 5% of body weight and many lost more than 15% of their body weight.³ Five studies of Mounjaro’s effect on blood glucose (A1c) levels, showed that it significantly lowers blood glucose compared to placebo when used alone or in combination with metformin.⁴
• Side effects of tirzepatide:* The most common side effects when taking tirzepatide medications include nausea, vomiting, diarrhea, dyspepsia, abdominal pain, and constipation. These effects usually are worse when starting or changing doses and should be monitored if they do not resolve on their own. There is also risk of more serious side effects like thyroid tumors, inflammation of the pancreas, and dangerously low blood glucose levels.^4,5
• What else you should know about tirzepatide: Tirzepatide should never be combined with any other peptide. Extra caution should be used when any peptide is combined with another antidiabetic drug, especially insulin or insulin secretagogues. Talk with your doctor or pharmacist before you begin treatment to review all other medications you take.^4,5

*All medications, including weight loss medications, can cause side effects which can be mild or serious. This is not a comprehensive list of all possible side effects. You should talk with your doctor about any questions you have and to understand the potential side effects and benefits of any medication.

Liraglutide (Saxenda & Victoza)

Liraglutide is available as a prescription injection under the names Saxenda and Victoza. Saxenda is FDA-approved to promote weight loss and maintain weight. A unique aspect of Saxenda is that it is the only peptide for weight loss that is injected once daily instead of once weekly. Victoza is FDA-approved to treat type 2 diabetes and reduce the risk of major cardiovascular events in certain people. While Victoza is sometimes used off label for weight loss, this use may prevent it from being covered by insurance.^6,7

• How liraglutide works: Liraglutide works through appetite suppression and delayed gastric emptying time, which can cause a person to feel full sooner and for longer leading to less calorie intake. The drug also improves insulin sensitivity which leads to lower levels of glucose in the blood.^6,7
• Effectiveness of liraglutide: Studies of Saxenda used for weight loss taking place over a year showed that about half of patients lost more than 5 %of their body weight. While this is significant and shows it can be effective, Saxenda is considered to be less effective than tirzepatide.^5,9
• Side effects of liraglutide:* The most common side effects when taking Liraglutide include nausea, vomiting, diarrhea, indigestion, abdominal pain, fatigue, and constipation. These effects usually are worse when starting or changing doses and should be monitored if they do not resolve on their own. There is also risk of more serious side effects like thyroid tumors, inflammation of the pancreas, and dangerously low blood glucose levels.^6,7
• What else you should know about liraglutide: Saxenda is injected once each day instead of once per week. This could be a determining factor in selecting a peptide medication for weight loss, especially if you have trouble with injections. This will also require additional injection pen needles to be prescribed or purchased at a pharmacy.⁷

*All medications, including weight loss medications, can cause side effects which can be mild or serious. This is not a comprehensive list of all possible side effects. You should talk with your doctor about any questions you have and to understand the potential side effects and benefits of any medication.

Is Compounded Semaglutide an Option for Weight Loss?

The FDA does not recommend using compounded semaglutide for weight loss, due to the safety risks of non FDA-approved products. The FDA has received reports of facilities using different versions of semaglutide that are not the same active ingredient and may not be safe or effective. While legally semaglutide can be compounded by an authorized and licensed pharmacy or outsourcing facility, there have been many reports of adverse events from compounded semaglutide use.⁸

Compounded semaglutide may seem like a good option due to price or availability, but you should proceed with extreme caution. Unauthorized versions of semaglutide can be dangerous and ineffective. If you do plan to seek out compounded semaglutide, be sure to have a valid prescription from your prescriber and utilize a fully licensed and authorized pharmacy. Be sure to ask the pharmacy specific questions, if the pharmacy is legitimate they will have no problem answering your questions.

Are Over-the-Counter Peptides for Weight Loss Available?

While over-the-counter products claiming to contain peptides for weight loss are available and marketed, they are not approved by the FDA and should be avoided. Dietary supplements do not need to prove safety or effectiveness to the FDA before being sold. This can put patients at risk of harm by taking products that can be harmful or ineffective.⁹

An alternative to over-the-counter peptides may be the use of certain supplements that affect peptide levels in the body. A study from 2021 found that some herbal based products can influence the body’s own GLP release. The herbal supplements studied were berberine, tea, curcumin, cinnamon, and gardenia. Talk to your healthcare team if you are thinking of taking any supplements in addition to your current medications.¹⁰

Who Are Weight Loss Peptides For?

Each approved peptide product for weight loss has a different set of parameters for use including age, BMI, weight, and other diseases. There are also specific conditions that will prevent a person from being able to use a peptide for weight loss. Selecting the correct weight loss peptide for each patient is an in depth process that requires health evaluations and a detailed review of a patient’s health history. Importantly, peptides for weight loss should never be used in patients who have type 1 diabetes.¹

The age range for use will also vary between branded products of the same peptide, based on the condition that is being treated. For instance, Wegovy is for weight loss and can be used by patients 12 years and up but Ozempic is used to improve glycemic control in patients with type 2 diabetes and is only approved for adults 18 years and older.^2,3 Both Mounjaro and Zepbound are only approved for use by adult patients 18 and older.^4,5 Saxenda is approved for use in patients 12 years and older who meet certain weight and BMI requirements and Victoza can be used in patients as young as 10 years old.^6,7

What Are the Criteria for Peptides for Weight Loss?

Each peptide for weight loss has specific criteria for use, based on BMI, age, body weight, comorbid diseases.¹ Your prescriber will help determine the proper medication to be used based on your specific health status and history. Wegovy and Zepbound do not have any weight restrictions, but require a patient to be either clinically obese or clinically overweight with one weight-related condition.^2,5

Saxenda is similar to its peptide counterparts, but when used in children 12 and older, requires a body weight of 60 kg (about 130 lbs) or higher.⁶ Your prescriber will help you understand which peptide is best for you and should take the time to explain their decision process with you.

Who Should Not Take Peptides for Weight Loss

Some patients should not use peptides for weight loss due to safety reasons.¹ This includes patients who:

• Are pregnant
• Are allergic to any GLP-1 agonists
• Are diagnosed with type 1 diabetes.
• Have a personal or family history of thyroid cancer
• Have a history of pancreatitis

You should talk with your healthcare provider about your entire medical history and any other medications you are taking. They will determine if weight loss medications are safe for you to take.

Can You Take Peptides for Weight Loss While Pregnant or Breastfeeding?

You should not use peptides for weight loss if you are pregnant or breastfeeding. In addition, you should stop using any peptide for weight loss at least 2 months before planning to become pregnant.^1,2 Studies in animals have shown that taking a peptide for weight loss can lead to fetal risk and death. Taking any medication during pregnancy is a decision that should be made with your health care team as it can put a fetus at risk.

Mounjaro specifically may reduce the effectiveness of hormonal contraceptives due to delayed gastric emptying time. It is recommended to use a non-oral contraceptive method or add a barrier method during and for 1 month after dose increases.⁴ Since all peptides for weight loss work in a similar way, this caution can reasonably be applied to all peptides for weight loss. Talk with your prescriber about options if you take hormonal birth control and plan to start taking a peptide for weight loss.

How Much Weight Can You Lose With Peptides?

Each person taking a peptide for weight loss will respond differently to the medication and experience varying outcomes. The amount of weight lost by a patient can be affected by a person’s starting weight, length of time taking a peptide, diet and exercise routine, and response to the medication and dose. To gather a general idea of potential weight loss, each medication provides data from studies used to prove the medication’s ability to cause weight loss.

Wegovy studies demonstrated that between 67% and 85% of patients lost more than 5% body weight after 68 weeks and between 25% and 50% of patients lost more than 15% body weight after 68 weeks.² Zepbound studies demonstrated that between 80% and 90% of patients lost more than 5% body weight after 72 weeks and between 40% and 70% of patients lost more than 15% body weight after 72 weeks.⁵

Saxenda studies demonstrated that between 45% and 60% of patients lost more than 5% body weight after 56 weeks and between 22% and 34% of patients lost more than 10% body weight after 56 weeks.⁶ These studies do not guarantee results and each person’s weight loss may vary.

How Long Do You Have to Take Peptides for Weight Loss?

Studies of peptides for weight loss show that to achieve weight loss between 5% and 20%, the peptide should be taken for about a year. Weight loss will begin within a month of taking the medication.^2,5,6 Taking care to administer your dose on time and as prescribed, can help ensure your treatment works as well as possible. Skipping or missing doses is not ideal, since sometimes you will need to start back at a lower dose.

What Happens After You Stop Taking Peptides for Weight Loss?

A continuous study exploring what happens when you stop taking a peptide has shown that up to two thirds of patients regain the lost weight after stopping Saxenda.¹¹ If you would like to stop taking peptides for weight loss, work with your prescriber to identify a safe and effective way to stop the medication.

If you plan to use the medication long term, attend routine follow-up appointments with your prescriber. Long-term use has not yet been studied and monitoring for serious complications like pancreatitis and certain cancers is essential.

Do You Need a Prescription for Peptides for Weight Loss?

Currently all injectable peptides for weight loss require a prescription from a licensed prescriber. Significant weight loss should be monitored by a qualified healthcare professional to ensure safety. Using a peptide for weight loss comes with significant risk and you should be able to contact your prescriber if anything happens. Injectable peptides for weight loss advertised without a prescription should not be used as they are not approved by the FDA.⁸

If you are utilizing a telehealth provider, be sure they can prescribe in your state. If you decide to seek out a compounded version of an injectable peptide for weight loss, you will still need a prescription.⁸

Peptides for Weights Loss in Combination With Lifestyle Changes

All peptides for weight loss are meant to be combined with a reduced calorie diet and increased physical activity. Studies conducted with each medication were done with patients who were also restricting calories and increasing physical activity.^2,3,4,5,6,7 These lifestyle changes can help to achieve intended weight loss results.

If you are unsure about how to make lifestyle changes or could benefit from professional help, ask your provider about consulting a dietician. Dieticians are licensed and can help build a sustainable plan for lifestyle changes. Change can be challenging and having the right support can help make transitions easier.

How Much Do Peptides for Weight Cost?

Injectable peptides for weight loss can be very expensive and are not always covered by insurance. Without insurance, these medications can cost thousands of dollars per month. Even with insurance coverage, copays can be hundreds or thousands of dollars depending on your plan and out of pocket responsibility.

Understanding the price of your medication is important to ensuring you will be able to continue taking the medication. Be sure to understand your insurance coverage and seek help from your pharmacy if you do not understand the price of your medication. In some cases there are coupons and copay assistance programs that can help reduce the cost.

Questions to Ask Your Healthcare Provider About Peptides for Weight Loss

Beginning treatment with a peptide for weight loss is a decision that should be made with your healthcare team. Take time to understand your treatment, the risks of treatment, and what to do if things do not go as planned. Be sure to ask about cost, discuss your health history, and understand how often you will be required to come for follow up appointments. Also be sure to ask someone from your healthcare team or your pharmacist to demonstrate proper injection technique if you have never used an injection medication.

Questions to ask your care team about peptides for weight loss include:

• How safe are peptides for weight loss?
• I have trouble with injections, are there other options?
• What should I do if my pharmacy cannot get my medication?
• How much will my medication cost?
• Is one brand of peptide better than the others?
• Why am I being prescribed this specific peptide for weight loss?
• Will I be prescribed any other medications in addition to my injectable peptide?
• How often will my dose change?
• What should I do if I want to stop using my medication?
• How long will it take for me to adjust to taking a peptide for weight loss?
• Am I at risk for more serious symptoms if I am already taking other medications?
• Will a peptide for weight loss allow me to lose weight and keep it off long-term?
• What should I do if I want to become pregnant?

How to Know if Prescription Peptides for Weight Loss Are Right for You

Determining if prescription peptides for weight loss are right for you will depend on your unique health status and health history. Work with your doctor to understand the best options for you. Understand that not everyone is a candidate for peptides for weight loss and safety should always be the top priority. The first step is to have an in-depth conversation with your health care team. Deciding to use a peptide for weight loss is a large decision that will affect your health and daily life, and should not be rushed.