TikTok Is Obsessed With Peptide Stacking for Better Fitness—But Is It Legit?

The phrase "peptide stacking" might conjure up images of a leaning tower of Pepto Bismol and brand-name laundry detergent. In reality, it's a new viral trend that's taking over fitness corners of TikTok—it has nothing to do with curing stomach woes or washing clothes. But it has everything to do with getting those gains.

Peptide stacking is a practice that involves taking several types of peptide supplements (i.e., amino acids or building blocks of protein) to achieve specific fitness goals like building muscle, burning fat, having more energy, and recovering from workouts quickly.¹ Instead of just taking one type of peptide at a time, people are taking multiple at once, in the form of tablets, powders, and yes, even injections.

Case in point: TikToker and nurse practitioner Kristina Stout has racked up more than 20,000 saves on this video of her peptide stacking routine for fitness goals. But there are plenty of other videos on social media of people sharing their peptide stacking routine, too. This begs the question: Does the popular fitness fad actually work (and is it safe)?

There’s no doubt people are interested in supporting their health and are curious about giving new trends a try when they pop up, says Roxana Ehsani, MS, RD, CSSD, LDN, a sports dietitian and nutrition media expert. On a broader scale, shifts in perspective on health are happening, too, according to Pooja Gidwani, MD, a board-certified internist and longevity and performance specialist in California.

“We’ve moved from reactive care to preventative care and now to assertive care," says Dr. Gidwani. "Optimization, regeneration, and performance enhancement are the new goals; peptides fit perfectly into that landscape," she adds. But does going hard at the gym mean you need to go hard with supplements, too?

Read on to learn whether peptide stacking is legit, or just another craze that's taken over your FYP. Ehsani and Dr. Gidwani share their expertise and research surrounding peptides here.

First, what is peptide stacking?

As mentioned, "peptides are chains of amino acids, the building blocks of protein,” Ehsani says. Your body uses amino acids to make proteins that help your body function at the most fundamental levels. This includes digesting food, repairing tissue, giving you energy, and assisting with growth.

There are 20 amino acids in total, all of which are either derived from food or produced naturally in the body. Some, like lysine, for example (an amino acid the body cannot produce on its own, so it's gathered from foods or supplements), may stimulate muscle growth.² Others, like arginine (an amino acid the body can produce), may enhance blood flow and reduce inflammation.³

Specifically, “peptide stacking involves combining different amino acid supplements to reap the benefits of all different types of peptides," says Ehsani. "Stacking them may enhance their effects or benefits."

While any combination of peptides is used to practice this method, Stout mentions three of the most popular types of peptide stacks in her TikTok video, along with their supposed benefits:

• AOD9604, Tesamorelin, and MOTS-c: A tablet or injection combination that claims to help people burn visceral (deep) fat, build muscle, and boost energy.⁴,⁵,⁶ It's also known online as the "fat burner blend."
• KLOW Stack (GHK-Cu): A copper peptide injection combination that supposedly helps reduce inflammation and joint pain, improve muscle recovery, and ease GI issues.⁷
• Wolverine Stack (BPC-157 and TB-500): A popular injection combination that supposedly helps improve tendon and muscle repair, reduce inflammation, ease GI issues, and improve overall well-being.⁸,⁹

So, should you try it? 

Dr. Gidwani says certain peptides have emerging evidence behind them for muscle retention, fat metabolism, and inflammation reduction. "They promise targeted improvements without the intensity or risk profile of full-blown pharmaceuticals, and they've been embraced by everyone from longevity influencers to high-performing executives," she adds.

But that doesn't mean you should stack them—it comes with risks, Dr. Gidwani adds. "When peptides are used responsibly—by the right person, in the right context—they can be powerful tools," she says. "But most people using peptides aren't doing it under medical supervision." Instead, "they're copying what they saw online or heard from a friend with no insight into whether it's aligned with their own physiology," she adds.

"When [peptides] are treated like plug-and-play solutions based on what someone else is doing, the results are often disappointing, or even harmful," Dr. Gidwani says. Plus, these supplements (like all other supplements) are not regulated by the Food and Drug Administration (FDA), so "technically anyone can create a peptide supplement and slap a label on it and sell it," Ehsani says. This is why you should never purchase peptide stacks (or any supplement, for that matter) from random stores or sellers online.

Because these stacks are not well-regulated, "there could be additional ingredients added to the peptide supplement that you may have an allergy to or be unsafe to consume," Ehsani says. "Or, the peptide itself could be dosed or prescribed in unhealthy amounts." A good reminder to always check with your healthcare provider before trying any new supplement.

Lastly, like with most other health and nutrition trends, there isn't enough research on its efficacy, Ehsani says. More research needs to be done on different populations and in various uses to determine whether peptide stacking actually works in place of tried-and-true sports nutrition tactics (like taking one provider-approved peptide supplement at a time).¹⁰

So, "if you’re looking to make fitness gains, you can’t overlook the fundamentals, which include eating a well-balanced diet and regularly incorporating strength training and aerobic exercise into your week,” Ehsani says.

This includes eating more whole foods like fruits and veggies, and getting your protein from high-quality sources that boost amino acids like dairy milk, Greek yogurt, seafood, poultry, and eggs, according to Ehsani. Additionally, the Centers for Disease Control and Prevention (CDC) recommends getting 30 minutes of cardio exercise five days per week and at least two days of strength training per week for optimal health.

Other tips to consider when using peptides

All that said, if you're still curious to try peptide stacking, Ehsani emphasizes checking in with your healthcare provider first to see if it's right for you. If they give you the green light, they can recommend proper dosages to reduce the risk of side effects and suggest supplements with third-party testing certifications from organizations like the NSF or Informed Sport (which verifies the supplements contain what the labels say they do).

Ultimately, "you need someone who can order the right labs, track biomarkers, and adjust dosing based on real data, not guesses," says Dr. Gidwani. "Without that level of personalization, it's not peptide therapy—it's biohacking roulette." She goes on: "Even the best peptide stack won't compensate for poor sleep, under-training, low protein intake, or unmanaged stress; you can't shortcut your way around fundamentals."

The bottom line

Like with any supplement, peptide stacking should only be tried under the care of a licensed medical professional, ideally an internal medicine, obesity medicine, or performance and longevity medicine provider, Dr. Gidwani says. Most prescription peptides are injectables that need to be dosed multiple times per week or day, and cycled appropriately to avoid tolerance and side effects, she adds.

“Over-the-counter peptides like collagen or L-arginine blends are widely available but do not offer the same clinical potency as prescription-grade compounds,” Dr. Gidwani says. “And this is critical: Avoid mass-market telehealth companies or ‘peptide clinics’ that provide templated stacks to everyone."

"If the same protocol is being handed out to hundreds of people with no labs, no history, and no follow-up, that’s not medicine—that’s a business model," Dr. Gidwani adds. So, before starting any peptide regimen, she recommends asking yourself the following questions:

1. 1.
   Who is recommending this, and are they medically trained to do so?
2. 2.
   Have they conducted a full evaluation of your health, goals, lab results, and lifestyle?
3. 3.
   Are they incorporating foundational strategies like sleep, nutrition, resistance training, and stress management into your plan?
4. 4.
   Are they tracking your labs, symptoms, and progress over time and adjusting the protocol accordingly?

If the answer to any of those is “no,” you should reconsider, Dr. Gidwani says. “Peptides are not supposed to be trendy—they’re supposed to be therapeutic," she says. "Used correctly, they can amplify results, but used blindly, they can waste your time, money, and health."

"The goal isn’t to mimic someone else—it’s to build a better, stronger version of you," says Dr. Gidwani. "And no matter how advanced your stack is, it will never outperform the basics.”