Essential amino acids (EAAs) are the 9 amino acids the body cannot synthesize and must take from food — they include the 3 BCAAs (leucine, isoleucine, valine) plus 6 more: lysine, methionine, threonine, phenylalanine, tryptophan and histidine. For muscle protein synthesis (MPS), what matters is the full profile, not just BCAAs.
Why it matters for an ultramarathoner in a deficit
- Lean-mass preservation in caloric deficit: when cutting, the risk is losing muscle along with fat. EAAs (especially leucine) keep MPS active and protect contractile protein — central in your low-carb + deficit scenario.
- Fasted morning training: a long session in a fast raises proteolysis. Intra-workout EAAs give the muscle substrate without breaking the fasted-burning state (10 g ≈ 40 kcal — negligible for ketosis).
- Long sessions (>60–90 min): from that point on, amino acid oxidation rises and blood BCAAs/EAAs drop. Replenishment reduces central fatigue (tryptophan:BCAA ratio) and muscle catabolism.
- Recovery: a post-workout dose also stimulates MPS — but in your protocol the breakfast/dinner whey already covers that. EAAs fill the fasted window.
- Long races (ultra): in a multi-hour ultra, sipping EAAs with hydration helps maintain the plasma pool and reduce chronic catabolism during the effort.
How it works (mechanism)
MPS is triggered mainly by leucine (via mTORC1), but the signal alone is not enough — without the other EAAs, there are no "bricks" to build protein. BCAAs alone can raise markers like phosphorylated mTOR, but actual synthesis does not happen without the simultaneous presence of the 9 EAAs (Wolfe 2017). That's why the literature has shifted in the last 10 years: EAAs > BCAAs for the goal of preserving/building muscle.
EAA vs. BCAA vs. Whey
| Item | Profile | Stimulates MPS? | When it shines |
|---|---|---|---|
| Whey | 9 EAAs + non-essentials | ✅ Strong | Post-workout, with a meal, full protein dose |
| EAA | 9 EAAs isolated | ✅ Strong (no milk calories) | Fasted, intra-workout, in a deficit |
| BCAA | 3 of 9 (leu, ile, val) | ❌ Signal without substrate — does not sustain MPS | Practically obsolete once you have EAAs |
Primary product: Nutricost EAA Powder
Nutricost EAA Powder delivers a blend of the 9 essentials with leucine emphasized, in a soluble powder for the training bottle.
- Composition/serving: ~10 g essential amino acids (leucine ~2.5–3 g, full 9-EAA profile)
- Container: 30 servings = 30 doses
- Price: $17.95 USD
- Cost/dose: ~$0.60 (R$3.08)
- Where to buy: Nutricost.com, Amazon US, iHerb
How to take
- Main timing (your case): in the pre/intra-workout bottle (fasted morning). 1 scoop (~10 g) in 500–700 ml water with electrolytes. Sip throughout the session.
- Fasted between meals: 10 g in water — useful in long no-food windows (e.g. pre-lunch on a stretched morning) for an MPS spike without significant calories.
- Long races (ultra): 1 serving every 2–3 h diluted in the hydration mix, alongside carbohydrate and electrolytes. Continuous anti-catabolic.
- Post-workout: if you'll have whey shortly after, EAAs are redundant. Use EAA when no meal/whey is available in the next 1–2 h.
- Not a "loading" supplement: effect is per dose. Skipping a day has no resume penalty.
Why it does NOT replace daily whey
EAAs do not bring the full calories and complete profile of a protein meal. Whey is still cheaper per gram of functional protein and has the thermic effect. EAAs are a strategic add-on for fasted windows — not a replacement for the whey in your meals.
- Severe renal insufficiency: protein/AA load increases renal work. Discuss with a nephrologist if you have a diagnosis.
- Phenylketonuria (PKU): contains phenylalanine — absolute contraindication.
- Urea cycle disorders (rare): elevated nitrogen can decompensate.
- "Taste": pure EAAs are strongly bitter (leucine especially). Flavored versions mask it well — not a product defect.
- Don't confuse with whey: EAA does not replace the daily total protein requirement — it's an adjunct.
Synergies / in your stack
- + HMB: classic anti-catabolic pair — HMB inhibits proteolysis (ubiquitin-proteasome), EAAs supply substrate for MPS. Especially synergistic in a deficit.
- + L-Citrulline/NitroVasc + carbs: vasodilation + insulin + AAs → amplified amino acid delivery to muscle pre-workout.
- + Collagen + Vit C (pre-workout): EAA covers muscle, collagen covers tendon/ligament. Complementary.
- + L-Arg + L-Orn: in long races EAAs supply substrate; Arg/Orn helps clear the ammonia generated by AA oxidation. Natural synergy.