Dileucine (DL185): Benefits, Evidence, and Is It Worth It?

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Search “dileucine” and you’ll find bodybuilding forums calling it the next big thing and supplement brands slapping “DL185” on their labels. Cut through the hype and there’s something genuinely interesting here: a leucine-based peptide with two actual peer-reviewed human trials behind it — which is more than most trending ingredients can claim. But “has some evidence” and “worth your money” are not the same thing. This article walks through exactly what dileucine is, what the research shows (with the real numbers), how it compares to ordinary leucine, and who is — and isn’t — likely to see anything from it.

What is dileucine (DL185)?

Dileucine is a dipeptide: two molecules of the amino acid L-leucine joined by a peptide bond, giving the chemical name L-leucyl-L-leucine. You’ll see it sold under trade names like DL185, Peptide-185, and ingredient brands such as RAMPS. Despite the futuristic branding, there is nothing exotic about the building block — leucine is one of the three branched-chain amino acids (BCAAs) and a normal component of any protein-containing food.

Leucine matters to lifters because it is the primary amino-acid “trigger” for muscle protein synthesis (MPS) — the process of building new muscle tissue. The theory behind dileucine is that packaging leucine as a dipeptide changes how it is absorbed and delivered, potentially producing a stronger or more sustained muscle-building signal from the same amount of leucine. Whether that theory holds up is exactly what the research tries to answer.

How it’s supposed to work (mTOR and MPS)

Inside muscle cells sits a signaling hub called mTOR (mechanistic target of rapamycin). When you eat protein — or specifically leucine — mTOR is activated and switches on the machinery that assembles new muscle proteins. This is why leucine, and leucine-rich whey, are so central to sports nutrition: leucine is the loudest single “start building” signal your muscles receive.

The dileucine hypothesis is about delivery. Dipeptides are absorbed through the gut by a dedicated transporter (PepT1) that is separate from the transporters used by single free amino acids. In principle, this could get leucine into the bloodstream in a form and concentration that stimulates mTOR more effectively than the same dose of free leucine. In the human studies, dileucine did raise blood leucine and produced a bigger jump in muscle protein synthesis than free leucine — consistent with a stronger mTOR signal. Just keep in mind this is a plausible, evidence-supported mechanism, not a fully mapped one, and mechanism alone never guarantees real-world results.

What the research actually shows

Two human trials form the entire meaningful evidence base for dileucine as a supplement. Both are worth taking seriously — and both come with real limits.

The 2021 metabolism study. Paulussen, Burd and colleagues, publishing in the Journal of Applied Physiology, ran a double-blind randomized controlled trial in 10 healthy young men. Participants ingested 2 grams of dileucine or 2 grams of leucine, and researchers tracked muscle protein turnover. The result: 2 g of dileucine raised muscle protein synthesis, while 2 g of plain leucine did not — the dileucine group showed roughly 42% greater synthesis of new muscle protein than the leucine group. That’s a striking difference for the same leucine dose, and it’s the finding the entire “dileucine beats leucine” claim rests on. The catch: it was an acute metabolic study in just 10 young men, measuring a molecular marker — not muscle you can see in the mirror.

The 2024 strength trial. Hagele, Kerksick and colleagues, publishing in PLoS One, ran a 10-week double-blind, randomized, placebo-controlled trial — the study design that actually tests whether an ingredient changes real outcomes. Thirty-four resistance-trained men (average age about 28) were split into placebo, leucine, and dileucine groups, taking 2 g daily while following a resistance-training program. The dileucine group showed significantly greater increases in leg-press one-rep max versus placebo, and greater leg-press reps-to-fatigue than the leucine group. Notably, there were no significant differences in upper-body strength, body composition, or muscle mass between groups. So the win was real but narrow: lower-body strength and performance, not size, and not everywhere.

The honest summary: two positive studies, both small, both in young, resistance-trained men, both short, and both showing benefits on top of training and protein — never in isolation. No trials yet exist in older adults, women, or sedentary people, and no long-term safety follow-up has been published.

Dileucine vs leucine — which is better?

On the current evidence, dileucine appears to out-perform an equal dose of leucine for stimulating muscle protein synthesis and (in one study) lower-body strength. But “better per gram in a study” doesn’t automatically mean “better for you.” Leucine is dirt cheap, extensively studied over decades, and easily obtained from whey protein and food. Dileucine is newer, pricier, and backed by two trials. The table below lays out the trade-offs.

Who might benefit — and who won’t

Might benefit: younger, already-training lifters who dial in their protein and want a small, evidence-backed edge on lower-body strength work — the exact population the studies were done in. If you fit that profile and have the budget, dileucine is one of the few “trending” ingredients with actual human data.

Probably won’t benefit much (or the data simply doesn’t exist): anyone hoping for a standalone muscle builder, people who don’t lift, those with inadequate protein intake (dileucine can’t substitute for total protein), and — importantly — older adults and women, who were not studied at all. Sarcopenia (age-related muscle loss) is a common reason people search for muscle supplements, but no dileucine trial has tested older bodies. If that’s your goal, the fundamentals matter far more; our guide to building muscle after 60 covers the protein and training strategies that are actually proven in that age group.

Dosing and safety

Both human trials used 2 grams per day, so that’s the only dose with any evidence behind it — more is not established as better, and megadosing has never been studied. In the 2024 trial, dileucine was taken daily alongside a training program for 10 weeks without reported problems.

On safety: the reassuring news is that dileucine is simply two molecules of leucine, an essential amino acid you consume every day in food. Your body has the machinery to break the peptide bond and handle the leucine. The honest caveat is that dedicated long-term safety data are limited — the trials were short and small, and there’s no research in pregnancy, in people with kidney or liver conditions, or over multi-year use. As with any supplement, if you have a medical condition or take medication, clear it with your doctor first. And to be clear about a common worry: dileucine is a food-derived amino-acid peptide, not a hormone or a steroid.

Is it worth it? (honest verdict)

Dileucine is one of the more legitimately interesting supplement ingredients to emerge recently — it has two real human trials, a plausible mechanism, and results that point in a consistent direction. That already puts it ahead of most of the supplement aisle. But the case is narrow: benefits so far are limited to young trained men, to lower-body strength rather than size, and only when stacked on top of proper training and protein. If your training and nutrition basics are already locked in and you want a modest, evidence-based extra, it’s a defensible buy. If you’re looking for a shortcut, or you’re outside the studied population, your money does more elsewhere. Dileucine is the headline ingredient in Advanced Muscle Plus — see our full review for how one popular product actually formulates it.

Frequently Asked Questions

What is dileucine?

Dileucine is a dipeptide made of two leucine molecules bonded together (L-leucyl-L-leucine). Leucine is the key amino acid that triggers muscle protein synthesis, and dileucine is a peptide form marketed as more effective per gram. It’s sold under names like DL185 and Peptide-185.

Does dileucine actually work?

In two small human trials it did produce measurable effects: a 2021 study found 2 g of dileucine raised muscle protein synthesis where the same dose of leucine didn’t, and a 2024 10-week trial found it improved lower-body strength in trained men. But the evidence is early — small groups, young trained males, short duration, and always combined with resistance training and adequate protein.

Is dileucine safe?

It’s a dipeptide of leucine, an essential amino acid you already eat daily, and the 2 g dose used in studies was taken for 10 weeks without reported issues. That said, dedicated long-term safety data are limited, and it hasn’t been studied in pregnancy, in people with kidney or liver disease, or over multi-year use. Check with your doctor if you have a health condition.

Dileucine vs leucine — which is better?

In the head-to-head 2021 study, dileucine outperformed an equal dose of leucine for stimulating muscle protein synthesis. However, leucine is far cheaper, far more studied, and readily available from whey and food. Dileucine may offer a per-gram edge, but leucine remains the more proven, cost-effective option for most people.

What is DL185?

DL185 (also called Peptide-185) is a trade name for dileucine — the same L-leucyl-L-leucine dipeptide discussed throughout this article. The branding sounds high-tech, but the underlying ingredient is a leucine-based peptide, not a novel drug.

Is dileucine a steroid?

No. Dileucine is not a hormone, drug, or anabolic steroid. It’s simply two molecules of a food-derived amino acid joined together. It works by supporting your body’s normal muscle-building signaling, not by altering hormones.

How much dileucine should I take?

Both published human trials used 2 grams per day, so that’s the only dose with evidence behind it. There’s no data showing higher doses work better, and megadosing hasn’t been tested. In the strength study it was taken daily alongside a resistance-training program.

Is dileucine worth the money?

It can be, for a specific person: a younger, actively training lifter with solid protein intake who wants a modest, evidence-backed edge — especially on lower-body strength. For everyone else (older adults, non-lifters, anyone hoping for a standalone muscle builder), the data either doesn’t exist or the basics will do more for less.

The Bottom Line

Dileucine (DL185) is a leucine dipeptide with something rare in the supplement world: two actual human trials suggesting it stimulates muscle protein synthesis better than plain leucine, and can improve lower-body strength in trained men. But the honest picture is a narrow one — the research is limited to young, resistance-trained males, in small samples, over short periods, and always paired with real training and adequate protein. It is a potential amplifier of good habits, not a replacement for them. If your fundamentals are in place and you fit the studied profile, it’s a reasonable, evidence-based extra. If not, spend your money on protein, progressive training, and sleep first.

Sources

1. Paulussen KJM, Alamilla RA, Salvador AF, McKenna CF, Askow AT, Fang HY, Li Z, Ulanov AV, Paluska SA, Rathmacher JA, Jäger R, Purpura M, Burd NA. “Dileucine ingestion is more effective than leucine in stimulating muscle protein turnover in young males: a double-blind randomized controlled trial.” Journal of Applied Physiology, 2021;131(3):1111–1122. https://journals.physiology.org/doi/abs/10.1152/japplphysiol.00295.2021
2. Hagele AM, Krieger JM, Gaige CJ, Holley KF, Gross KN, Iannotti JM, Allen LE, Sutton PJ, Orr LS, Mumford PW, Purpura M, Jäger R, Kerksick CM. “Dileucine ingestion, but not leucine, increases lower body strength and performance following resistance training: A double-blind, randomized, placebo-controlled trial.” PLoS One, 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC11687731/
3. University of Illinois News Bureau. “Study identifies molecule that stimulates muscle-building in humans.” 2021. https://news.illinois.edu/study-identifies-molecule-that-stimulates-muscle-building/