The Claim

Leucine supplementation at 7.5 g/day (2.5 g per meal) provides no additional benefit to basal muscle protein synthesis, muscle fiber growth, lean mass gain, or frailty reduction in older women already consuming optimized protein intake (1.2 g/kg/day) during resistance training.

Source: Resistance training, but not leucine, increased basal muscle protein synthesis and reversed frailty in older women consuming optimized protein intake.

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
72score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Cause and effect
1 study reviewed
In plain English

In older women who already eat enough protein and do resistance training, taking extra leucine supplements does not improve muscle protein synthesis, muscle growth, lean mass, or reduce frailty.

See the scientific wording

Leucine supplementation at 7.5 g/day (2.5 g per meal) provides no additional benefit to basal muscle protein synthesis, muscle fiber growth, lean mass gain, or frailty reduction in older women already consuming optimized protein intake (1.2 g/kg/day) during resistance training.

Why this might work

When older women do strength training and eat enough protein, their muscles sense the physical stress and turn on a system that builds more muscle proteins. Adding extra leucine does not make this system work any better because the muscle already has all the signals it needs from the workout and the protein it already eats.

Verified mechanismbased on 1 study

What the research says

1 study
  1. Study: Resistance training, but not leucine, increased basal muscle protein synthesis and reversed frailty in older women consuming optimized protein intake.

    In older women who already eat enough protein and do strength training, taking extra leucine pills didn’t help them build more muscle or get stronger or less frail—just doing the workouts and eating well was enough.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.