By Marnie Kunz, NASM-certified trainer, USATF- RRCA-certified running coach

Peptides for weight loss are becoming increasingly popular, with drugs like Wegovy and Ozempic taking the weight loss industry by storm. But what are peptides exactly, and how can they help with weight loss? This guide will go over how peptides work and the different types of peptides and offer insights from doctors, researchers, and patients on the benefits and risks of using peptides for weight loss.

Peptides are short chains of amino acids that play different roles in your body, including regulating metabolism, stimulating growth hormone production, and suppressing appetite. Some peptides have been effective for weight loss and are becoming increasingly popular as a treatment for obesity and weight-related issues.

What Are Peptides?

Peptides are naturally occurring substances in the human body that make up proteins. They are strings of amino acids linked together by peptide bonds. A peptide's sequence of amino acids determines its unique structure and function. Peptides can be classified based on their size and structure, including:

Oligopeptides are short chains of amino acids, typically less than 20 amino acids in length.
Polypeptides are longer chains of amino acids, ranging from 20 to 100 amino acids in length.
Proteins are large, complex molecules composed of multiple polypeptide chains.

How Do Peptides Work?

Peptides have different functions depending on the type of peptide. Peptides that are popular in the weight loss industry can perform a variety of roles, including reducing appetite, slowing digestion, increasing insulin production, regulating blood sugar, increasing metabolism, and stimulating growth hormone release.

Can Peptides Help with Weight Loss?

Peptides for weight loss can be effective, according to researchers. Glucagon-like peptide-1 (GLP-1) agonists are increasingly popular for weight loss because they reduce appetite and promote fullness. GLP-1 agonist class of medications are often used for the treatment of type 2 diabetes and obesity since they help regulate blood sugar.

According to the Mayo Clinic, the drugs stimulate your body to produce more insulin when blood sugar levels rise (such as after eating). The extra insulin helps lower blood sugar levels. GLP-1 medications slow digestion, assisting people to feel full more quickly when eating and stay satiated longer. This helps with weight loss.

Types of Peptides for Weight Loss

The below peptides have helped people lose weight and fall under the category of GLP-1 agonists. These drugs can curb appetite and increase feelings of fullness when eating.

Semaglutide

Common Brands: Wegovy, Ozempic
Treatment: Weekly injections
Common Side Effects: Nausea, diarrhea, vomiting, and constipation
Less Common Side Effects: Gastroparesis (stomach paralysis), pancreatitis, gallbladder disease, and worsening of diabetic retinopathy

Semaglutide medications are behind the boom in weight loss drugs as they have been proven in studies to help people lose weight. Semaglutide for weight loss is most commonly sold under the brand names Ozempic and Wegovy.

“Ozempic and Wegovy are the same drug, semaglutide,” says Dr. Aleem Kanji, a board-certified endocrinologist and obesity medicine specialist in Houston.

Ozempic vs. Wegovy for Weight Loss

The difference between the two drugs is that Ozempic is FDA-approved for treating diabetes, and Wegovy is approved as a weight loss treatment for obesity. Wegovy is, therefore, the drug of choice for weight loss. Wegovy is usually injected once a week for weight loss treatments.

You may wonder how much weight people lose with these popular forms of semaglutide. The amount of weight loss people experience with these drugs can vary depending on the individual and other health factors.

“The STEP 1 trial is the best data to answer how much weight can be lost with once weekly injectable semaglutide,” Kanji says. “At the end of 68 weeks in the trial, individuals in the semaglutide group lost an average of 14.9% of their body weight, compared with 2.4% in the control group.”

The reported 15 percent average weight loss has caused a lot of excitement among researchers and patients, as many weight loss drugs are linked with smaller weight loss percentages.

Side Effects of Semaglutide

Researchers generally report mild side effects in people who take semaglutide for weight loss, and the side effects can diminish over time. However, there are cases of severe side effects, including stomach paralysis and pancreatitis.

“Common side effects with semaglutide include nausea, vomiting, diarrhea, abdominal pain, constipation, and headaches,” Kanji says. “Strategies for reducing or managing side effects include a slow titration, adequate hydration, and use of medication for symptom control as needed.”

It’s important to work with your doctor and determine if you’re a good candidate for these peptides for weight loss. If you experience any severe or uncomfortable side effects, seek medical care.

“Less common but serious adverse effects seen in the clinical trials are pancreatitis (inflammation of the pancreas), gallbladder disease (such as gallstones), and worsening of diabetic retinopathy,” Kanji says.

Indeed, a recent study found that there can be less common but severe side effects of semaglutide, including stomach paralysis, bowel obstruction, and pancreatitis.

Patient Experiences with Semaglutide

Patients report a range of experiences with semaglutide, ranging from successful weight loss to serious medical complications. Mish Perez is a NYC runner with diabetes who was prescribed Ozempic. She experienced no side effects and lost some weight while on the drug for a little over a year.

“I actually did really well on it,” Perez says. “I did not have any side effects. It actually helped me lose a little bit of weight. About 2 years ago, while on Ozempic, I was a size 2 in pants. Now I’m between 4 and 6.”

Perez says she changed medications and stopped taking Ozempic because she needed a different drug to regulate her blood sugar levels better.

Alexis Hope Krase is a Brooklyn mom who was an early adopter of Ozempic for weight loss. Krase says, “It nearly ruined my life.”

“There wasn’t a ton of knowledge about side effects then,” Krase says. “I basically had a fertility doctor who wanted me to lose weight quickly and suggested that I take the drug. I kind of blindly agreed to do so because I was desperate to get pregnant. The short of it is I developed a side effect called gastroparesis - stomach paralysis.”

This severe side effect gave Krase ongoing vomiting spells, and she was unable to keep her food down while taking Ozempic.

“I couldn’t keep food down,” she says. “I was uncomfortable 24/7. It persisted far beyond when I stopped the medication. It took months to get a diagnosis because, at the time, nobody knew that it was a common side effect. I was vomiting daily. I could only eat liquid foods. It was awful. Luckily, it slowly reversed over time, which is not the case for many.”

Krase is not alone, as more patients report stomach paralysis and uncontrolled vomiting from GLP-1 agonist drugs. Despite people’s experiences, the FDA has not included the side effects on labels. More comprehensive studies on the link between the drug’s delaying food digestion and stomach paralysis need to be done.

Liraglutide

Common Brand: Saxenda
Treatment: Daily injections
Common Side Effects: Mild or moderate nausea and diarrhea
Less Common Side Effects: Gastroparesis (stomach paralysis), pancreatitis, gallbladder disease, and worsening of diabetic retinopathy

Liraglutide is another form of GLP-1 agonist that is used for weight loss. As with semaglutide, liraglutide curbs appetite. Saxenda is a liraglutide approved by the FDA for ongoing weight management. According to the FDA guidelines, Saxenda is approved for adults with a BMI of 30 or higher or a BMI of 27 or higher who have at least one weight-related condition.

In contrast with Wegovy, which is given weekly, Saxenda is usually given as a daily injection for weight loss. According to a study of liraglutide, 63.2 percent of patients lost at least 5 percent of their body weight when taking the drug, and 33.1 percent lost more than 10 percent of their body weight.

Some experts recommend semaglutide over liraglutide as the costs of liraglutide can be high. According to researchers, the price needed to lose 1% of body weight with liraglutide is estimated at $3,256 compared with $1,845 with semaglutide.

Tirzepatide

Common Brand: Mounjaro, Zepbound
Treatment: Weekly injections
Common Side Effects: Gastrointestinal upset, nausea, vomiting, diarrhea, and constipation

Tirzepatide is another GLP-1 that can help with losing weight. Mounjaro is prescribed for diabetes treatment but is sometimes used off-label for weight loss (similar to Ozempic). Zepbound, on the other hand, is a brand of tirzepatide that is FDA approved for weight loss.

According to researchers, tirzepatide can lead to “substantial weight loss” when used regularly. Zepbound is FDA-approved for people with a BMI of 30 or higher or for people who are overweight with a related health condition, such as high cholesterol, high blood pressure, or diabetes.

Tirzepatide is usually administered with a weekly injection. Common side effects include gastrointestinal problems such as nausea, vomiting, diarrhea, and constipation.

Pros and Cons of Peptides for Weight Loss

Pros

Peptide drugs offer effective weight loss for many people.
Losing weight can reduce your risk of health conditions such as type 2 diabetes, high cholesterol, and cardiovascular disease.
For people who are overweight with co-existing conditions, peptides can help treat related conditions such as type 2 diabetes.
Peptides are a non-surgical form of weight loss treatment.

Cons

Cost can be a barrier for many people to access peptides for weight loss. Medicare and many insurance plans do not cover weight loss or obesity management drugs.
Gastrointestinal upset is a common side effect of these weight loss medications. Symptoms may subside over time, but some do not decrease and can be severe. Talk to your doctor if you have ongoing or severe side effects.
Only some people who use peptide drugs for weight loss will lose weight. Although the majority of people lose weight, some people do not experience weight loss, according to experts. Individual lifestyle and exercise habits, as well as the body’s response to drugs, can affect someone’s results.

Choosing the Best Weight Loss Program for You

Peptides are a form of amino acid chains that are found naturally in the body. Some peptides have been proven to cause weight loss by reducing appetite and increasing feelings of fullness. If you are overweight or obese and would like to try weight loss medication, talk to your doctor about the best options for you. Your health status, pre-existing conditions, and lifestyle can all play a role in weight loss, and your doctor will consider these when planning your weight loss treatment.

“I don’t have one drug I recommend overall for people as anti-obesity medication should be individualized based on a person’s medical history, preferences, concerns, and the medication’s cost/insurance coverage,” Dr. Kanji says.

Talk to your doctor if you’re considering using peptides for weight loss. Healthy eating and regular exercise are crucial to losing and maintaining a healthy weight and should be an integral part of any weight loss program.

If you need a realistic and healthy weight loss fitness plan, head to the Runstreet Training Center.

Marnie Kunz is a NASM-certified trainer and USATF- and RRCA-certified running coach based in Brooklyn, NY. Marnie likes helping people get and stay active to enjoy a better quality of life. When she’s not doing fitness things, Marnie enjoys exploring with her dog, a mischievous rescue Akita.

Peptides For Weight Loss: Types, Benefits, and Risks