PlainPill

Leucine

The short answer. There isn't much data on Leucine yet — 25 mentions, 8 with a clear outcome — so treat these numbers as anecdotal. It is most often used for performance: 100% of 6 reports say that improved. It is well studied — 267 meta-analyses on PubMed.

What users report
88%helped8 reports · few reports
7 helped1 mixed0 didn't help

From 25 mentions in total — the rest didn't say how it went and aren't counted.

Clinical research
AStrong research base
267
meta-analyses
827
RCTs
68,549
papers

What Leucine does, according to users

Of the people who reported each effect, the share who said it got better.

What the research says

Systematic reviews and meta-analyses from PubMed, with their published conclusions.

AStrong research base

3+ meta-analyses or systematic reviews and 10+ randomized controlled trials in humans. The grade measures how much human research exists — read the conclusions below for what it found.

Br J Sports Med · 2018 · Meta-analysis / systematic review
A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults

Conclusion: Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET in healthy adults. Increasing age reduces and training experience increases the efficacy of protein supplementation during RET. With protein supplementation, protein intakes at amounts greater than ~1.6 g/kg/day do not further contribute RET-induced gains in FFM.

PubMed 28698222 ↗
Cochrane Database Syst Rev · 2024 · Meta-analysis / systematic review
Nutritional interventions for preventing and treating pressure ulcers

Conclusion: The benefits of nutritional interventions with various compositions for pressure ulcer prevention and treatment are uncertain. There may be little or no difference compared to standard nutrition or placebo. Nutritional supplements may not increase gastrointestinal side effects, but the evidence is very uncertain. Larger studies with similar nutrient compositions would reduce these uncertainties. No study investigated the effects of special diets (e.g. protein-enriched diet, vegetarian diet) on pressure ulcer incidence and healing.

PubMed 38345088 ↗
Nutrients · 2023 · Meta-analysis / systematic review
Effects of Whey Protein, Leucine, and Vitamin D Supplementation in Patients with Sarcopenia: A Systematic Review and Meta-Analysis

Conclusion: In addition, the appendicular muscle mass significantly increased regardless of the presence of a concomitant physical exercise program; (4) Conclusions: Whey protein, leucine, and vitamin D supplementation can increase appendicular muscle mass in patients with sarcopenia. In addition, combining a physical exercise program with whey protein, leucine, and vitamin D supplementation can improve muscle strength and function.

PubMed 36771225 ↗

Dosage people report

As stated by users — not a recommendation. Follow the label or your doctor.

5 gdaily
2gfasting morning
5 gas reported
3 gdaily
3.5 gper serving

Reported side effects

How often each side effect came up across all reports.

No side effects reported so far.

What users say

First-hand experiences, quoted verbatim. We show one positive and one negative where both exist.

“on a cut I ramp leucine intake through the roof (both through eating more protein generally and also through BCAA and pure luecine supplementation) and I find it helps me retain lean mass better.”
HelpedRead the discussion ↗
“even a small amount (3/4 grams leucine or 5/6 grams bcaa) before resistance training or sports makes a huuuuge difference in my doms”
MixedRead the discussion ↗
“I only need L-Leucine, so that's what I take, 10mg before training fasted. It's supposed to help you build muscle by spiking insulin”
HelpedRead the discussion ↗
Top discussions (4)

Other options for performance

User data from public discussions; research from PubMed. Information only, not medical advice — talk to a doctor before starting, stopping or combining anything. Data updated October 3, 2026. How we rate