Supplement companies often claim peptides can amplify muscle gain and facilitate fat loss. But few studies have explored the impact of peptides on bodybuilding, and some are banned in professional sports.

Peptides are a popular performance-enhancing aid in the bodybuilding community. They’re short chains of amino acids, which are small molecules that are the building blocks of peptides and proteins.

Peptides exist naturally in your body, but you can also find them in animal or plant sources of protein. Manufacturers can isolate these peptides or make them by combining individual amino acids.

You can purchase peptide supplements as a powder that you can mix with a liquid and consume orally. Alternatively, you can find them in injectable form.

Some people view peptides as a more natural alternative to anabolic steroids, praising them for their ability to boost muscle mass, promote fat loss, and help bodybuilders maximize their workout results.

However, scientific research on these purported benefits is limited and mixed.

Keep reading to learn more about the possible benefits and risks of using peptides for bodybuilding.

Peptides can have structures similar to those of certain hormones and signaling compounds in the body, allowing them to engage with and activate multiple receptors throughout the body, thereby influencing various bodily processes.

Many also have the ability to penetrate tissues.

Depending on their sequence and composition, certain peptides may help prevent blood clots, boost the immune system, protect cells against damage, and reduce cholesterol, inflammation, and blood pressure.

Specific peptides may also help boost the release of hormones known to stimulate muscle growth, body fat loss, and exercise performance and recovery. This makes them particularly appealing to bodybuilders seeking to maximize their training results.

Bodybuilders are typically interested in changing their body composition as quickly and efficiently as possible. Research suggests that certain peptides may help them achieve these goals.

Growth hormone secretagogues (GHS) are a group of peptides that attract particular interest among bodybuilders because they can stimulate the production and release of human growth hormone (HGH).

HGH is a hormone secreted by the pituitary gland. It may help enhance muscle growth and indirectly promote body fat loss by stimulating the liver to release insulin-like growth factor-1 (IGF-1). In turn, IGF-1 stimulates muscle protein synthesis and promotes muscle growth.

Back in the 1980s, HGH was a popular performance-enhancing drug among various recreational and professional athletes, including bodybuilders. But, due to safety concerns, regulating bodies like the International Olympic Committee banned the off-label use of HGH from 1989 onward.

Some people claim that GHSs offer many of the same benefits as HGH with fewer side effects. This may explain their popularity as an alternative to HGH among bodybuilders.

While some research suggests that GHS increases the release of HGH or IGF-1 in humans, more studies are needed to determine whether taking GHS actually leads to significant changes in body composition, exercise performance, or recovery.

What’s more, no studies have examined the effect of GHSs on well-trained individuals, so scientists currently don’t know which muscle groups peptides may affect most, or which workouts they might be best suited for.

Bodybuilders may be particularly interested in GHS peptides. The most popular GHSs for bodybuilding include:

  • growth-hormone releasing hormones,such as sermorelin, tesamorelin, CJC-1293, and CJC-1295
  • ghrelin and compounds mimicking its actions,such as lenomorelin, anamorelin, ipamorelin, macimorelin, and tabimorelin
  • growth hormone-releasing peptides (GHRPs), such as alexamorelin, GHRP-1, GHRP-2, GHRP-3, GHRP-4, GHRP-5, GHRP-6, and hexarelin

Each of these peptides may stimulate the production and release of HGH, although they do so in slightly different ways.

Manufacturers often promote each category for slightly different purposes. However, it’s important to note that no studies to date have investigated the effects of GHSs in bodybuilders or other highly trained individuals.

Therefore, indications and recommended dosages are typically based on anecdotal evidence rather than science.

The safety of using GHSs over the short and long term is unknown. Studies investigating their safety have been limited in size and duration. Therefore, scientists need to conduct further research to investigate the safety of GHS.

According to a 2017 review, common side effects of using GHS may include:

  • increased appetite
  • elevated blood sugar levels
  • fluid retention

GHSs may also decrease the body’s sensitivity to the hormone insulin, making it more difficult to regulate blood sugar levels. There may also be a risk of contamination if people use non-sterile needles to inject GHS.

The Food and Drug Administration (FDA) has only approved certain types of GHS for use in treating specific medical conditions under a prescription. GHSs are also currently on the World Anti-Doping Agency’s list of prohibited substances.

Despite this, you can purchase many GHSs from supplement-selling websites without a prescription.

Doing so may carry some risks, as the long-term safety of these supplements is unclear, and it’s virtually impossible to evaluate the quality of the purchased supplement. For these reasons, the use of GHSs for off-label or nonprescription purposes is not recommended.

Consider speaking with a doctor before taking peptide supplements if you’re pregnant, breastfeeding, taking any medications, or have a certain health condition.

Peptide supplements are generally considered safe because they’re often made by isolating naturally occurring peptides in food.

However, since supplements aren’t regulated by the FDA, it’s not always possible to determine the type, quantity, and quality of the ingredients in a product.

No, peptides are not steroids. Peptides are amino acid chains that occur naturally in your body and some foods, while anabolic steroids are artificial hormones.

A 2022 animal study found that some peptides may increase testosterone in rats, but studies in humans are needed to understand the effects of peptides on testosterone.

Some research found that people experienced increases in muscle strength and mass after 8 to 12 weeks of taking peptides in combination with resistance training.

Supplement companies often tout peptides as a means to boost muscle growth, promote fat loss, or enhance workout performance and recovery.

However, limited research supports these claims, and there’s little evidence available on the effects of peptides in well-trained individuals like bodybuilders.

Moreover, GHS peptides are currently a banned doping agent in professional sports, and little is known about their long-term safety. Using them may also cause health concerns, and they’re currently only approved to treat a handful of specific medical conditions.

For all these reasons, the off-label or nonprescription use of GHS peptides in bodybuilders is not recommended.