💉Peptide Mania: What Active Midlife Women Need to Know 

Peptides are having a moment in midlife health. And if ongoing political pressure succeeds in loosening FDA restrictions on more than a dozen of these drugs, it could turn into a pretty big movement (and honestly, some would rightly contend, it already kinda is), because they could be compounded under physician supervision (i.e., not FDA-approved), rather than being fully approved as FDA‑regulated drugs.

If you feel confused by the whole online peptide conversation, you’re not alone. So, this week, I figured we’d offer an explainer for what active midlife women need to know.

What the Heck Are Peptides?

First things first, what are peptides anyway? Peptides are short chains of amino acids that act as messenger molecules in the body, telling cells to do things like grow, repair, or secrete hormones. They’re part of our normal physiology, like insulin and GLP-1. They’re also being manufactured and sold as prescription medications, compounded injections, and supplements.  

Right now, people using the term “peptides” are often referring to an emerging array of health and wellness supplements that at this time are largely unregulated and pretty questionable. But, there are various types of peptides that fall into different categories:

• FDA‑approved drugs such as GLP‑1 agonists for diabetes and obesity.

• Oral supplements such as collagen peptides.

• Health, performance, or wellness injections like growth‑hormone–releasing peptides, BPC‑157, TB‑500 and others, often prescribed off‑label or sold online.

For those of us who are training, maybe racing, and navigating menopause, a lot of these can sound pretty promising: more lean mass, easier fat loss, better recovery, fewer aches, and “anti‑aging.” The key is unpacking which of these claims rest on solid human data in women—and which are still mostly theory, extrapolation, or marketing.

GLP‑1s and Metabolic Peptides

Let’s start with the ones that we’ve all heard of at this point: the GLP‑1 receptor agonists like semaglutide (aka Ozempic) and dual agonists like tirzepatide (aka Mounjaro). GLP‑1 receptor agonists such as semaglutide and tirzepatide are engineered peptide drugs modeled on the natural GLP‑1 peptide hormone; they activate the same receptor but are not identical to the body’s native GLP‑1. Originally developed to regulate blood sugar in type 2 diabetes, they are now widely used for weight loss. 

These are becoming increasingly popular in midlife women and some emerging research suggests they can generate more weight loss when used along with hormone therapy. A recent subgroup analysis of tirzepatide across multiple trials found that women in pre‑, peri‑, and postmenopause all experienced similar reductions in body weight and waist circumference compared with placebo, with ~23–26% weight loss versus 2–3% on placebo and waist reductions around 20 cm versus 4–5 cm. Another 2026 report suggested that combining menopause hormone therapy with tirzepatide produced greater weight loss in postmenopausal women than tirzepatide alone, suggesting synergy between HT and GLP‑1–based meds.

As we’ve talked about on the Hit Play Not Pause podcast, active women have unique considerations when using these drugs, because they can make fueling for training and racing more challenging, and could, in theory, raise the risk for low energy availability and REDs. You also need to pay special attention to maintaining muscle and bone, especially if you lose weight rapidly.

In short, this is a space where we have real data in midlife women, but very little that is athlete‑specific. If you’re considering GLP‑1s, you need a plan to protect muscle, bone, and performance through resistance training, protein, and (when appropriate) HT.

Collagen Peptides

Collagen peptides are hydrolyzed, broken-down pieces of animal collagen that are more easily absorbed by the body than full-length collagen proteins. They’re pretty popular among our audience members and have decent evidence behind them (though it’s worth noting that many trials are small and/or industry funded). 

In a 12‑week randomized, placebo‑controlled trial on women (premenopausal in this one) doing regular resistance training, 15 g/day of specific collagen peptides led to greater gains in fat‑free mass and hand‑grip strength, and larger reductions in fat mass, than training plus placebo. Similar work in older men with sarcopenia found collagen plus lifting improved muscle mass, strength, and fat loss more than lifting alone. 

Another trial in recreationally active women doing concurrent training (strength and running) also reported 12 weeks of combined cardio and strength training with daily collagen peptides (15g) led to greater gains in muscle mass and running endurance distance, similar fat loss, and overall better body composition improvements compared to training with placebo. A 2022 review concluded that collagen peptide supplementation could promote recovery, decrease pain, and improve strength and body composition when paired with resistance training.

Bottom line: collagen peptides aren’t magic, but combined with a solid resistance program they may give a small bump in lean mass and body‑composition changes, and may help connective tissue adapt to training and promote favorable shifts in bone markers. Doses used in research usually cluster around 15 g/day. 

“Performance/Recovery” Peptides 

Here’s where we enter the gray zone and where folks need to tread carefully (if at all). The online longevity and anti-aging market is booming with these peptides, generally in two categories: 

• Growth hormone (GH) releasing peptides/secretagogues (e.g., CJC‑1295, ipamorelin, sermorelin) and FDA‑approved analogs like tesamorelin (approved specifically for HIV-associated lipodystrophy)--all marketed off-label for fat loss, muscle gain, better sleep, and “anti‑aging.”

• Tissue‑repair peptides like thymosin beta‑4 derivatives (TB‑500) and BPC‑157, promoted for faster healing of tendons, ligaments, and gut.

This is the wild west, because while there’s evidence that some GH‑related peptides can increase growth hormone and IGF‑1 levels and influence body composition in clinical contexts, robust, long‑term trials in healthy active adults (like us) are largely absent. For BPC‑157 and TB‑500, much of the evidence is preclinical or anecdotal; high‑quality human RCTs in sports injury rehab are scarce.

Importantly for anyone racing under anti‑doping rules: USADA and WADA classify many peptide hormones, growth hormone analogues, growth hormone fragments (like AOD‑9604), GH‑releasing peptides, and growth factors such as thymosin beta‑4/TB‑500 as prohibited substances. USADA explicitly notes that peptide hormones with anabolic or strength‑enhancing effects are banned under the WADA Prohibited List.

These drugs often come from compounding pharmacies or even unlabeled “research chemical” sites. These peptides—such as BPC‑157 and TB‑500—are not FDA‑approved for any medical use. Regulators have specifically warned that quality, purity, and safety are not assured. You may not really know what you’re getting.

There’s also a question of what kind of harmful side effects they can have. One that comes up is cancer growth. The concern isn’t that these peptides cause cancer, but that they may theoretically step on the gas pedal of growth in cells you’d rather keep quiet—especially in a life stage when breast and other cancers already become more common. We need research here.

Midlife athletic women deserve access to therapies that meaningfully improve health span and performance, but the bar for injecting powerful signaling molecules should always be higher than “someone on Instagram said it worked.” I’d stick to the ones where the evidence is sound and you can buy properly sourced and tested products.