BCAA Dosage Calculator

What is BCAA?

Branched-chain amino acids (BCAAs) comprise three essential amino acids — leucine (primary mTOR activator), isoleucine (glucose uptake), and valine (central fatigue reduction) — at a typical 2:1:1 ratio (leucine:isoleucine:valine). BCAAs are metabolised primarily in skeletal muscle (unlike most amino acids, which are catabolised in the liver), making them immediately available as both oxidative fuel and anabolic signals during exercise. Two mechanisms drive BCAA's performance relevance: (1) leucine activates mTORC1 signalling and stimulates muscle protein synthesis acutely; (2) valine and isoleucine compete with tryptophan for the same blood-brain barrier transporter — elevated plasma BCAA reduces central tryptophan uptake and serotonin synthesis, delaying central fatigue during prolonged endurance exercise. The critical caveat confirmed by recent meta-analyses: BCAAs provide meaningful benefit primarily when total dietary protein is insufficient (< 1.2 g/kg/day), or during fasted training. In athletes meeting adequate total protein targets (1.6–2.2 g/kg/day), whole protein sources (whey, casein) provide superior anabolic stimulation at equivalent leucine exposure.

How to Take BCAA

**During fasted training or in caloric deficit:** 0.1–0.15 g/kg body weight intra-workout or immediately pre-workout (7–10 g for most adults). **For central fatigue reduction during endurance exercise (> 90 min):** 5–10 g taken 30 minutes before and every 45–60 minutes during prolonged sessions. **Post-workout:** 5–10 g alongside a complete protein source or as part of a caloric restriction protocol where complete meals are unavailable. A 2:1:1 leucine:isoleucine:valine ratio is standard; some products use 4:1:1 or higher leucine ratios, which may provide greater mTOR stimulation at the cost of the other BCAAs' independent functions.

Timing Recommendations

**Intra-workout and pre-workout are the primary windows** where BCAAs provide unique value — specifically during fasted training, prolonged endurance, or where food cannot be consumed. Post-workout BCAAs are partially redundant if a complete protein meal follows within 1–2 hours. For endurance athletes: take 5 g 30 min before, then 3–5 g per hour during exercise > 90 minutes to maintain plasma BCAA levels and reduce perceived exertion.

Potential Side Effects & Safety

BCAAs are extremely well tolerated at standard doses (5–20 g/day). Mild GI discomfort occasionally occurs with large doses (> 20 g) on an empty stomach. A high-leucine diet has been associated with reduced insulin sensitivity over long periods in some studies, though this is not established as a concern at typical supplemental doses. BCAA supplementation can interfere with some amino acid blood tests — disclose to your physician before metabolic testing.

Best Stacks with BCAA

BCAAs are a bridge supplement — their role diminishes as total protein intake optimises. For fasted training: BCAAs + caffeine + beta-alanine covers the three acute exercise performance parameters. For endurance: BCAAs + electrolytes + beetroot as an intra-workout endurance stack. Upgrade from BCAAs to EAAs (essential amino acids) when budget allows — EAAs provide all 9 essential AAs including complete mTOR signalling.

Scientific References

All dosage recommendations are grounded in peer-reviewed research.

1. 1
   Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?

   Journal of the International Society of Sports Nutrition · 2017

2. 2
   Effects of BCAA supplementation on exercise-induced muscle damage: a meta-analysis

   Nutrients · 2020