SLU-PP-332

Most of the interest comes from women in their forties and fifties who've noticed that the same walk, the same meals and the same sleep don't produce the same body they used to. They're looking at SLU-PP-332 for metabolism and fat loss, for stamina on the days when climbing the stairs feels like a project, and as part of a broader healthy-aging plan alongside things like MOTS-c and NAD+.

The reason is one headline. In 2023 a team at Saint Louis University and Washington University reported that mice given SLU-PP-332 for a week ran about 70% longer and 45% farther on a treadmill than mice that didn't get it, without any extra training. A follow-up in obese mice found they burned more energy, burned more fat for fuel and put on less fat, with better insulin sensitivity. The press called it exercise in a pill, and the name stuck.

The same research group, with kidney researchers at Georgetown, gave it to elderly mice for eight weeks and saw the aging kidney's energy machinery and inflammation shift back toward a younger pattern. Another study with the same group gave it to mice with failing hearts and saw the heart muscle work better. That's why it shows up in longevity conversations and not only weight ones.

The one study that used human tissue is the one most relevant to women in midlife. A team in Italy took small muscle samples from women having hip replacements, split by how active they'd been, and found the inactive women's muscle had lower levels of the receptor SLU-PP-332 targets. They then grew muscle cells from the inactive women's samples in the lab and treated them with SLU-PP-332. The treated cells showed less wear from oxidative stress, the cell version of rust, and fewer signs of cell aging, and formed healthy muscle fibers more readily. That was cells in a dish, not women taking a capsule, but it's the first look at the compound on human muscle.

Every finding in living animals is in mice. People who take it report on forums that it's subtle, and some say they notice more stamina on walks or in workouts, but that's reported experience and nothing has measured it.

Your muscle cells carry a set of switches called estrogen-related receptors, or ERRs. Despite the name, they don't respond to estrogen. They sit in the cell's control room and turn on the genes for building and running mitochondria, the little power plants that burn fat and sugar for energy. A brisk walk flips these switches. So does a long bike ride.

SLU-PP-332 flips them without the walk. Think of it as someone else pressing the button on the coffee maker: the coffee still gets made, you just didn't get up for it. In mice, that meant muscles shifted toward the slow, tireless fiber type that endurance athletes build, and their bodies ran more on fat.

What it doesn't do, as far as anyone has shown, is the rest of what exercise does: the bone loading, the balance, the heart working harder, the mood lift after. Researchers call it an exercise mimetic, a copy of one part of exercise, and the copy is partial. All of the mechanism work so far is in mice and in cells.

SLU-PP-332 is a powder that doesn't dissolve in water. Chemical suppliers list it as insoluble in water and soluble in DMSO, a lab solvent. That one fact shapes how it's sold.

Capsules are the most common form. Vendors sell them at 250 mcg or 500 mcg each, in bottles of 30 to 100. Vendor pages give 250 to 500 mcg a day, and that's the only human-facing amount in circulation. No study sets it, and the SLU-PP-332 dosage page lays out where each figure comes from.

The catch is that the developers themselves describe SLU-PP-332 as lacking oral bioavailability, meaning not much of it gets into the blood when swallowed. Every mouse study gave it by injection into the abdomen, at amounts per pound of body weight far above what's in a capsule. Nobody has published how much of a capsule actually reaches muscle, so the capsule question is open, and it's the first one to ask.

Vials of powder come in 5 mg and 10 mg sizes. Because the powder won't dissolve in plain or bacteriostatic water, mixing a vial isn't the instant-coffee job it is with a true peptide, and no source we trust gives an injected amount for people.

Nobody knows, and that's the plain answer. No human study of any size has been published, so there's no list of side effects, no known interactions and no data on pregnancy or breastfeeding. The mouse studies didn't report obvious harm over a few weeks, and a few weeks in a mouse is a short window.

A few things need extra care. ERRs are active in the heart, liver and kidneys as well as muscle, so a compound that turns them up acts body-wide, not just in your legs. The vial form raises its own issue, since a powder that won't dissolve in water doesn't belong in a syringe until someone can say what it's dissolved in. And two anti-doping labs have already published methods to detect it in urine, which tells you sports authorities take it seriously.

Most of the research comes from one research group and the people working with it, and some of those researchers hold stakes in companies developing ERR drugs. That isn't a red flag on its own, it's how drug discovery usually starts, but it means independent replication is thin.

Buying smart matters more than usual here. Look for a vendor that posts a third-party test showing the compound's identity and purity, and compare the real price per milligram rather than the price per bottle, since capsule counts and strengths vary so much.

SLU-PP-915 is the newer sibling from the same lab. It's a chemically different molecule that hits the same three receptors, and in a 2026 mouse study it worked when swallowed, matching SLU-PP-332's endurance effect. The researchers developed it precisely because SLU-PP-332 doesn't absorb well by mouth.

Some vendors have started listing it. Amounts don't carry over between the two, since they're different molecules that absorb differently.

No regulator has approved SLU-PP-332 as a medicine, in the US or anywhere else. In the US it's legal to buy and sell as a research chemical, the same way most compounds on this site are. Rules differ by country, so check locally if you're outside the US. If you compete in a tested sport, anti-doping labs can now detect it.

We haven't written a side-by-side for SLU-PP-332 yet. The compounds people most often weigh it against are MOTS-c, a peptide also studied as an exercise mimetic, and 5-Amino-1MQ, another small molecule bought for metabolism and fat loss. For energy at the cell level, SS-31 works on the mitochondria directly.