Does leucine work?

Overall Effectiveness Rating for Leucine

The overall effectiveness rating for leucine is 1.6 out of 3. This rating means there is some evidence that using leucine may lead to positive results. This rating also means that some evidence does not back up all claims. Below you can find individual ratings for specific claims.

Overall Confidence Rating for Leucine

There are 11 studies in the database on leucine; the confidence rating is 51. A score above 80 means the effectiveness rating for this supplement is reliable. A score under 80 means there is insufficient evidence to ensure a reliable effectiveness rating. Note, this rating is for leucine as a whole. There are also individual ratings for the claims below.

Products Containing Leucine

Products Containing Leucine
Merica Minos
Signature Pre Workout
Post Jym Active Matrix
Sinner Outbreak
Amino Lean Energy Formula
Full list of all 53 products containing Leucine.

Individual Claims

The overall ratings above do no necessarily reflect each claim about leucine. Individual claims can have higher or lower ratings. For example, some supplements may have a lot of backing for one claim, but be completely useless for another. Click on claims below for more information.

Body Composition (weight, muscle, body fat) Claims Effectiveness Rating Confidence Rating
increase muscle mass

Protein Synthesis Claims Effectiveness Rating Confidence Rating
decrease protein breakdown
increase protein synthesis

Performance Claims Effectiveness Rating Confidence Rating
increase strength

Recovery Claims Effectiveness Rating Confidence Rating
improve recovery
reduce muscle damage
reduce muscle soreness


Title of Study
Co-ingestion of leucine with protein does not further augment post-exercise muscle protein synthesis rates in elderly men.
Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects
Effect of leucine supplementation on indices of muscle damage following drop jumps and resistance exercise
Effects of leucine and its metabolite β‐hydroxy‐β‐methylbutyrate on human skeletal muscle protein metabolism
Effects of Whey, Soy or Leucine Supplementation with 12 Weeks of Resistance Training on Strength, Body Composition, and Skeletal Muscle and Adipose Tissue Histological Attributes in College-Aged Males
Free leucine supplementation during an 8-week resistance training program does not increase muscle mass and strength in untrained young adult subjects
Hydrolyzed casein and whey protein meals comparably stimulate net whole-body protein synthesis in COPD patients with nutritional depletion without an additional effect of leucine co-ingestion
Leucine as a regulator of whole body and skeletal muscle protein metabolism in humans
Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis
Observations of Branched-Chain Amino Acid Administration in Humans
The Effects of Adding Leucine to Pre and Postexercise Carbohydrate Beverages on Acute Muscle Recovery From Resistance Training