These peptides boost metabolic function in your 40s.
Peptides like sermorelin, ipamorelin, and tesamorelin are gaining traction in fitness and longevity circles for their promise to restore energy, aid weight loss, and build muscle. Unlike many trendy treatments that dominate social media, peptide therapy isn’t just hype—it’s backed by solid science. By boosting growth hormone production naturally, these peptides address the root causes of midlife changes like stubborn belly fat, sluggish recovery, and dwindling energy.
When you enter your mid-thirties, your body makes less growth hormone (GH), a key player in muscle growth, fat metabolism, and appetite regulation (1). “This drop reduces our ability to recover from inflammation and exercise, decreases muscle mass and strength, and zaps energy—all while increasing fat accumulation,” internal medicine doctor and peptide expert Jessica Cho, M.D. says.
Peptide therapy can reverse these effects by boosting growth hormone levels, supporting weight loss (especially around the belly), and improving energy (1). Sermorelin, ipamorelin, and tesamorelin are among the most popular options for HGH peptides, according to Cho. We break down how each one works—and how to choose which is right for you.
About the Experts
Jessica Cho, M.D., is an internal medicine physician specializing in weight management and peptide therapy at her practice, Wellness at Century City.
James R. Staheli, D.O., is the Medical Director for Broad Health, Hone Health’s affiliated medical practice, and a family medicine doctor specializing in men’s hormone health.
Sermorelin is a synthetic version of the naturally occurring growth hormone-releasing hormone (GHRH), a naturally-occuring peptide that tells your pituitary gland to release more growth hormone (2). Like GHRH, sermorelin also binds to GHRH receptors in the pituitary gland.
This process increases the amount of growth hormone that your body can use for fat metabolism, muscle building, and energy.
Similar to sermorelin, ipamorelin signals the pituitary gland to release more growth hormone.
Instead of mimicking GHRH and acting on its receptors in the brain, ipamorelin acts as a go-between (1). It binds to the receptors of another hormone, ghrelin, which also stimulates the pituitary gland to release growth hormone (1).
Like sermorelin, tesamorelin binds to GHRH receptors in the pituitary gland to release growth hormone. However, this synthetic peptide is more potent than sermorelin. It was designed specifically to reduce visceral (belly) fat in people with conditions like HIV (3).
Sermorelin, ipamorelin, and tesamorelin are peptides that increase the production of growth hormone. Your body uses this extra growth hormone to develop lean muscle mass and maintain a healthy weight, James Staheli, D.O., explains. However, each HGH peptide has a slightly different effect on weight loss and metabolic function.
Unlike HGH injections—which involve directly injecting a synthetic growth hormone— peptides like sermorelin and ipamorelin stimulate the natural release of HGH hormone from the pituitary gland.
“This is better for long-term health optimization as well as longevity,” Cho says. Injecting growth hormone directly has been linked to type 2 diabetes, gynecomastia (man boobs), swelling and joint pain, and a higher risk of certain cancers (4). Stimulating the pituitary gland with peptides like ipamorelin to make more growth hormone has none of these effects.
Sermorelin has a half-life of around 11 to 12 minutes, meaning half of the peptide is processed by the pituitary gland within this time (5). According to a 2020 review, sermorelin can double growth hormone levels for up to 12 hours after injection, with levels peaking around the two-hour mark (1).
There are no human clinical trials on ipamorelin’s ability to increase growth hormone (1). But, studies with mice suggest that ipamorelin’s half-life is longer than sermorelin—it lasts around 2 to 3 hours. Tesamorelin has a half-life of around 26 to 38 minutes (6). A longer half-life means ipamorelin and tesamorelin may trigger growth hormone production longer than sermorelin.
Sermorelin, ipamorelin, and tesamorelin are self-injected subcutaneously (right under the skin). Ipamorelin may also be offered as a pill. Dosage can vary, but most protocols recommend daily injections for all three peptides.
Because most growth hormone is naturally secreted at night, many people choose to take their injections before bed to simulate the body’s natural process (7).
If you have a condition like HIV or a genetic growth hormone deficiency, your insurance may cover growth hormone peptides. However, you’ll likely have to pay out of pocket to receive hormone peptides for anti-aging, weight loss, or muscle building.
Sermorelin costs between $200 to $500 per month on average. Sermorelin is $130 per month through Hone, with a membership.
Ipamorelin runs between $150 and $600 per month out of pocket. Tesamorelin can cost up to $3,000 a month without insurance (8).
Boosting growth hormone levels with peptides like sermorelin, ipamorelin, and tesamorelin can support overall health with the following benefits:
However, you’ll need to pair peptides with a healthy lifestyle to maximize these benefits, according to Staheli. “Growth hormone peptides are synergistic with a clean diet, cardio and resistance exercise, sleep optimization, stress reduction, and additional supplements,” Staheli says.
Alongside these shared benefits, sermorelin, ipamorelin, and tesamorelin have unique perks, too.
Sermorelin may mimic the body’s natural “pulsatile” release of growth hormone (9). In other words, when you inject sermorelin, it prompts the pituitary gland to release growth hormone in its natural pattern. This rhythm is thought to maintain your body’s responsiveness to the peptide over time.
Like sermorelin, Cho says ipamorelin is also a good choice for those seeking overall vitality, muscle preservation, and fat loss as part of an anti-aging routine. What sets ipamorelin apart is its gentle approach.
By binding to ghrelin receptors, ipamorelin can raise growth hormone levels without impacting other hormones like cortisol (10). This makes ipamorelin a more precise option for increasing growth hormone, according to Cho.
Animal studies also suggest that ipamorelin may support bone formation, which could support healthy aging (11).
Tesamorelin is the most potent growth hormone peptide for weight loss, as it triggers the strongest metabolic response out of all three peptides. “It’s highly effective for people looking to target abdominal or visceral fat,” Cho explains.
Visceral fat is linked to metabolic disorders, inflammation, and increased cardiovascular risk (12). “Because of this effect, tesamorelin is also being explored for anti-aging and longevity purposes,” she says.
Ipamorelin and sermorelin tend to have minimal—if any—side effects. In rare cases, you might experience the following mild side effects while your body adjusts to sermorelin and ipamorelin (2):
Tesamorelin may have unique side effects like joint swelling, arm or leg pain, and muscle stiffness (3). If you experience these, Cho says to report them to your doctor.
Injectable peptides like sermorelin, ipamorelin, and tesamorelin can replenish declining growth hormone levels, making it easier to lose weight, build muscle, and gain energy. The primary differences between them are how they increase growth hormone, their cost, and some side effects.
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