By: Lainey Younkin, MS, RD

If you’re on a weight loss journey, you’ve probably heard about peptides. But what are the best fat burning peptides? Are they the same as GLP-1 medications? What does the science say about peptides and weight loss? And, most importantly, do they work?

In this post, we explain what peptides are, what the science really says about their effectiveness, and the best peptides for fat burning.

What Are Peptides?

Peptides are short chains of amino acids that act as building blocks for proteins in your body. While proteins contain 50+ amino acids, peptides contain fewer (typically 2-50 amino acids). Your body naturally creates peptides for various functions, including hormone regulation, muscle growth, and metabolism. 

Synthetic peptides are made in a lab and mimic the properties of natural peptides. For example, collagen peptides are used in protein powders and supplements for hair, skin, and joint health. 

Glucagon-like peptide-1 receptor agonists (GLP-1 agonists), such as semaglutide and tirzepatide, are synthetic peptides used in injectable weight loss medications that mimic the effects of natural GLP-1 in the body, like regulating blood sugar and reducing appetite. 

This article focuses on the best peptides for weight loss and fat burning.

How Do Fat Burning Peptides Work?

Peptides marketed for fat loss, including GLP-1 medications, typically work through one or more of these mechanisms:

1. Slowing gastric (stomach) emptying – GLP-1 medications slow digestion and the release of food from your stomach, which means you feel full longer. 
2. Increasing satiety (fullness) – GLP-1 agonists send signals to the brain that increase the feeling of fullness. 
3. Stimulating release of insulin – GLP-1 medications stimulate the release of insulin from the pancreas, which lowers blood sugar.
4. Increasing growth hormone production – Some fat burning peptides stimulate your pituitary gland to release more growth hormone, which can help with fat metabolism.
5. Boosting metabolism – Certain peptides may increase your metabolic rate, helping you burn more calories throughout the day.
6. Preserving lean muscle – Some peptides help maintain muscle mass while losing fat, which is crucial for a healthy metabolism.
7. Improving insulin sensitivity – Some fat burning peptides improve insulin function, which can help regulate blood sugar and reduce fat storage.

The Best Fat Burning Peptides

The three most effective fat burning peptides, which have been approved by The Food and Drug Administration (FDA), are the GLP-1 agonists: semaglutide, liraglutide, and tirzepatide. 

1. Semaglutide (Wegovy®, Ozempic®, Rybelsus®)

• Brand names: Marketed as Wegovy® for weight management, Ozempic® for type 2 diabetes, and Rybelsus® for type 2 diabetes.

• How it works: Weekly injection that mimics GLP-1 to reduce hunger, increase feelings of fullness, and slow digestion.
• Approval:
  • Wegovy® – FDA-approved for obesity (BMI ≥30) in combination with reduced-calorie diet and physical activity for long-term weight management. It is also approved for those who are overweight (BMI ≥27) with at least one weight-related comorbid condition (e.g. high blood pressure, type 2 diabetes, or dyslipidemia). Wegovy® is also FDA-approved for children over the aged 12 and older with an initial BMI at or above the 95th percentile for their age and sex.
  • Ozempic® – FDA-approved in combination with diet and exercise to improve blood sugar control in adults with type 2 diabetes. May also reduce risk of cardiovascular disease in people with or without diabetes. 
  • Rybelsus® – FDA-approved in conjunction with diet and exercise for enhancing glycemic control in adults with type 2 diabetes.
• Effectiveness: Clinical trials show an average weight loss of 15-17% of body weight after 68 weeks when combined with lifestyle changes.

2. Liraglutide (Saxenda®, Victoza®)

• Brand names: Marketed as Saxenda® for weight management and Victoza® for type 2 diabetes.
• How it works: Daily injection that works similarly to semaglutide but with a shorter half-life, requiring more frequent dosing.
• Approval:
  • Saxenda® – FDA-approved for weight management for adults with obesity (BMI ≥30) or who are overweight (BMI ≥27) and have a weight related comorbid condition. Also approved for children aged 12 and older who are obese.
  • Victoza® – FDA-approved in conjunction with diet and exercise to improve blood sugar control in adults with type 2 diabetes, as well as children aged 10 and older. Also approved to reduce risk of cardiovascular events in adults with type 2 diabetes and heart disease.
• Effectiveness: Clinical trials show an average weight loss of 5-7% of body weight after 56 weeks when combined with lifestyle changes.

3. Tirzepatide (Mounjaro®, Zepbound®)

• Brand names: Marketed as Mounjaro® for type 2 diabetes and Zepbound® for weight management
• How it works: Weekly injection that uniquely targets both GLP-1 and GIP (glucose-dependent insulinotropic polypeptide) receptors, offering a dual approach to appetite regulation and metabolism
• Approval: FDA-approved for adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition
  • Mounjaro® – FDA-approved along with diet and exercise for blood sugar control in adults with type 2 diabetes.
  • Zepbound® – FDA-approved for weight management in adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition (e.g. high blood pressure, type 2 diabetes, or high cholesterol) in addition to a reduced calorie diet and exercise.  
• Effectiveness: Clinical trials show an average weight loss of 16-22.5% of body weight after 72 weeks when combined with lifestyle changes, making it the most effective FDA-approved medication for weight loss to date.

Other Fat Burning Peptides

1. CJC-1295/Ipamorelin

What it is: A combination of two peptides that stimulate the release of growth hormone (GH). CJC-1295 also stimulates the secretion of insulin-like growth factor. 

How it’s claimed to work: Growth hormone declines with age and is associated with a decrease in lean body mass and increase in fat tissue. By increasing growth hormone levels, CJC-1295/Ipamorelin claims to enhance fat metabolism while preserving lean muscle. 

Research status: While research shows that these peptides do increase growth hormone, there’s limited research on if this affects fat metabolism or muscle mass. Most research is in lab settings or animal models. It’s also important to note that these peptides interact with many medications.

2. Tesamorelin

What it is: A synthetic growth hormone-releasing hormone (GHRH) analog.

How it’s claimed to work: Stimulates the production of growth hormone, which may help reduce visceral fat (the dangerous fat around organs in the abdomen).

Research status: Tesamorelin is FDA-approved for reducing excess abdominal fat in HIV patients with lipodystrophy, but not approved for general weight loss use. There are limited studies on the effects of tesamorelin on visceral fat in those without HIV. A 2012 randomized controlled trial found that 2 milligrams of tesamorelin per day reduced visceral fat in adults with obesity who had reduced GH secretion. 

At this time, tesamorelin is not recommended or approved for general weight loss. It is not safe if you are pregnant, could become pregnant or breastfeeding. It may also increase blood sugar and increase risk of cancer.

3. AOD-9604

What it is: A modified fragment of human growth hormone.

How it’s claimed to work: Supposedly stimulates lipolysis (fat breakdown) and inhibits lipogenesis (fat formation) without affecting blood sugar levels.

Research status: The development of this drug was stopped in 2007 because it failed to induce significant weight loss in a 24-week trial of 536 subjects. Limited evidence supporting its effectiveness for fat loss in the general population.

4. BPC-157

What it is: A peptide derived from gastric juice.

How it’s claimed to work: Though primarily marketed for healing and recovery, some claim it supports general metabolic health.

Research status: Limited human studies exist, particularly for fat loss claims. BPC-157 has not been extensively studied in humans, so it is unclear if it is safe or effective. It is also prohibited under the World Anti-Doping Agency (WADA) Prohibited List.

5. Sermorelin

What it is: A synthetic form of growth hormone-releasing hormone (GHRH).

How it’s claimed to work: Stimulates the natural production of growth hormone, which people claim can increase metabolism and fat burning.

Research status: Currently used to treat poor growth in children and in some cases used to treat growth hormone deficiency in adults. While there are claims that sermorelin could be used for anti-aging or muscle building, there’s no solid evidence that it helps with either. 

6. HCG (Human Chorionic Gonadotropin)

What it is: A hormone produced by the placenta during pregnancy.

How it’s claimed to work: Supposedly helps burn fat while preserving muscle when combined with a very low-calorie diet.

Research status: There’s no credible scientific evidence that supports HCG for weight loss. The FDA has warned against HCG weight loss products, calling them “fraudulent” and “illegal.”

What Does Science Actually Say?

Most peptides marketed for fat loss have limited human research backing their effectiveness. Not only that, but they could be dangerous to take or increase risk of certain diseases like cancer. The exceptions are prescription GLP-1 agonists, like semaglutide, liraglutide, and tirzepatide, which have substantial clinical evidence and FDA approval for weight management.

For most other peptides:

• Research is preliminary: Many studies are in test tubes or animals, not humans.
• Safety profiles are unclear: Long-term effects are largely unknown, and it’s not clear what dose is safe to take.
• Quality control issues: The peptide supplement market is poorly regulated. In other words, are you actually getting what they say you are getting?
• Availability concerns: Many are not legally available without a prescription.

Potential Risks and Side Effects

Before considering any peptides for fat loss, be aware of these potential risks:

Risks and Side Effects of GLP-1 Agonists

• Injection-related issues: Most peptides require injection, which can carry risk of infection.
• Dosing issues: Compounded versions of these medications can lead to dosing errors. The FDA does not test or approve compounded versions for safety or efficacy.
• Gastrointestinal (GI) side effects: GLP-1 agonists can cause GI issues such as nausea, constipation, or diarrhea. Usually these are mild and go away with proper nutrition management, and not everyone experiences these side effects.
• Other side effects: Although less common, other side effects can include hypoglycemia, pancreatitis, gallbladder disorders, gastroparesis, trouble sleeping, eating disorder, or anxiety.
• Harm to fetus: GLP-1 medications and fat burning peptides are not recommended during pregnancy, and it is recommended to come off of them before trying to conceive.

Risks and Side Effects of Other Fat Burning Peptides

• Injection-related issues: Most peptides require injection, which can carry risk of infection.
• Hormone disruption: Peptides affecting growth hormone can disrupt your body’s natural hormone balance.
• Unknown long-term effects: Many of these peptides haven’t been studied for extended use. Some of them could increase the risk of serious adverse health events, such as cardiac issues.
• Cost: Peptide therapies are expensive and rarely covered by insurance. For a therapy that hasn’t been proven, it’s worth considering the cost to benefit ratio.
• Quality concerns: The market can include counterfeit or impure products since these are not regulated.

A Sustainable Approach to Fat Loss

While fat burning peptides may aid weight loss, they shouldn’t be the only tool in your weight loss toolbox, especially if you want to optimize overall health. Nutrition, exercise, sleep, and stress all affect your hormones and metabolism, which affect weight and overall health.

There are two main things you want to consider when using peptides for fat loss: the first is how to optimize nutrition and maintain muscle mass while taking the medication, and the second is your long-term maintenance plan.

Weight regain is common after stopping GLP-1 medications, and most people who take them will need to take them for life to sustain the results. In a 2022 study, participants regained two thirds of the weight they had lost in a year after stopping semaglutide.

These medications are intended to be used long-term. However, if you do decide to stop taking the medication, you’re more likely to maintain more of your weight loss if you also made lifestyle changes while on the medication, such as eating more protein and fiber and doing strength training.

Whether you’re using fat burning peptides or not, you should focus on the following habits for sustainable weight loss.

1. Balanced Nutrition

• Adequate protein (25-30g protein per meal)
• Fiber-rich vegetables and fruits (30-35g fiber per day)
• Healthy fats like avocados, nuts, and olive oil
• Complex carbohydrates (e.g. whole grains, potatoes) in appropriate portions

These foods and nutrients help naturally regulate hunger hormones and keep you full.

2. Strength Training

Adults lose 3-8 percent of muscle mass every decade after the age of 30. When you lose weight, you don’t just lose fat but also muscle. This means taking a GLP-1 medication could lead to muscle loss if you aren’t doing anything to preserve that muscle. 

The more muscle you have, the more calories you burn at rest, so you can keep your metabolism from slowing down as you age by lifting weights. Not only that, but weight lifting gives you a lean and toned look. Start small and build up. We recommend 20-40 minutes, 3-4 times per week and encourage women to increase how much weight they’re lifting as they get stronger over time.

3. Adequate Sleep

Poor sleep disrupts the hormones that regulate hunger and fat storage. Lack of sleep leads to increased ghrelin, the hunger hormone. Aim for 7-9 hours of quality sleep.

4. Stress Management

Chronic stress increases cortisol, which promotes the storage of belly fat. Incorporate stress-management techniques like breathing, meditation, and walking. 

5. Consistency Over Perfection

Sustainable fat loss comes from consistent habits you can maintain for life, not extreme measures or unproven supplements. Remember whatever you do to lose weight you have to keep doing to maintain the weight loss.

When to Consider Medical Weight Loss Options

If you’ve consistently implemented lifestyle changes and aren’t seeing results, speak with your healthcare provider about evidence-based medical options may be appropriate. This might include FDA-approved medications like GLP-1 receptor agonists or other interventions.

The Bottom Line on Fat Burning Peptides

While peptides may sound promising and cutting-edge, most lack substantial evidence for fat loss in healthy individuals. The exceptions are GLP-1 agonists like semaglutide, liraglutide, and tirzepatide, which are prescription medications that require medical supervision.

GLP-1 medications are life-changing for many people. Obesity is a complex condition that disrupts some hormones from being able to do their jobs properly. This means that for some people, no matter how healthy they eat and how much they exercise, they still can’t lose weight. It has nothing to do with their willpower and everything to do with how their bodies are operating. 

If you feel like this is you, then GLP-1 agonists may be a great option. However, if you’re simply chasing the next fat burning trend, remember that the first place to start is doing the basics on repeat: balanced nutrition, regular strength training, adequate sleep, and stress management. These factors work synergistically to create a metabolic environment that supports healthy fat loss.

If you’re considering trying a fat burning peptide that has not been approved for weight loss, consider where you are getting it from, remembering that whether it’s an injection or pill, these are not regulated for safety, quality, or efficacy. Many can interact with other medications and carry other health risks, so it’s always important you tell your healthcare provider what you are taking.

FAQs About Fat Burning Peptides

Are peptides safe for weight loss?

Prescription peptides (like GLP-1 agonists) used under medical supervision are FDA-approved and considered safe. Compounded versions of these medications or other peptides marketed for fat loss that have not been FDA-approved may come with safety concerns.

How much do fat burning peptides cost?

It depends on which peptide and if it is covered by your insurance. Some people pay over $500 per month, while others pay much less. Some places sell peptide injections for hundreds or thousands of dollars, but keep in mind that many of the peptides used in these settings are not FDA-approved.

Do peptides work better than diet and exercise?

It depends on the person and their goals. Some people can achieve their weight loss goals with diet and exercise alone. For others, GLP-1 medications have been the only way they have been able to lose a significant amount of weight. Studies show that through lifestyle changes alone, most people can’t lose more than 5-10 percent of their weight and actually maintain it. With GLP-1 medications, that percentage is much higher, closer to 15-20 percent or more of weight lost.

Can I take peptides in pill form?

Most peptides are destroyed by stomach acid, which is why they are typically administered via injection. Oral peptide supplements are unlikely to be effective for this reason.

How long does it take to see results with peptides?

For prescription peptides like GLP-1 agonists, most clinical trials show measurable results within 4-12 weeks when combined with lifestyle changes.

Looking for help on your sustainable weight loss journey? Whether you’re on a GLP-1 medication or not, we can help. Book a call to learn more or download our FREE GUIDE: 5 Habits for Sustainable Weight Loss for Busy Working Moms.