EAAs (Essential Amino Acids)
The 9 amino acids your body can't make on its own. If you're training and not getting enough protein from food, these are the building blocks your muscles are missing.
EAAs are the 9 amino acids your body can't produce — you have to get them from food or supplements. They're the only amino acids that directly trigger muscle protein synthesis, making them the most important group for building and maintaining muscle.
Good for you if: You train fasted, struggle to eat enough protein, are cutting calories, or want a low-calorie way to boost muscle protein synthesis around workouts.
Dive deeper into the researchCommon side effects
- Mild nausea or bloating at high doses (15 g+)
- Bitter taste — most powders need flavouring
- Rarely, GI discomfort if taken on a completely empty stomach
What do EAAs do?
Your body needs 20 amino acids to build proteins. It can make 11 of them on its own. The other 9 — the essential ones — have to come from what you eat or drink. Without all 9 present, your body can't fully trigger muscle protein synthesis (MPS), the process that repairs and grows muscle tissue.
The 9 EAAs are: leucine, isoleucine, valine, lysine, methionine, phenylalanine, threonine, tryptophan, and histidine. Of these, leucine is the primary trigger for MPS — which is why it's dosed highest in quality EAA products.
What can you expect?
- Better muscle recovery — faster repair after resistance training
- Muscle preservation on a cut — helps prevent breakdown when calories are low
- Reduced soreness — less DOMS (delayed onset muscle soreness) after hard sessions
- Fasted training support — protects muscle without breaking your fast with a full meal
- Low-calorie protein boost — ~50 kcal per 10 g serving vs ~120 kcal for a whey scoop
How to take them
10–15 g mixed in water, sipped during your workout. Look for a product with at least 3 g leucine per serving. Powder form absorbs faster than capsules.
If you train fasted, start sipping 10 minutes before your session and continue throughout.
Timing: Peri-workout (before/during) is ideal. You can also take them between meals if you're struggling to hit your protein target.
What to look for: A full 9-EAA profile with leucine as the dominant amino. Avoid products that are just BCAAs with a couple of extras sprinkled in — check the amino acid breakdown on the label.
EAAs vs BCAAs
This is the biggest question in the amino acid world. Here's the simple answer:
| EAAs | BCAAs | |
|---|---|---|
| Amino acids | All 9 essential | Only 3 (leucine, isoleucine, valine) |
| Triggers MPS? | Yes — fully | Partially — needs the other 6 to complete |
| Best for | Fasted training, low-protein diets, cutting | Intra-workout flavour, marginal soreness benefit |
| Cost | Slightly higher | Cheaper |
| Bottom line | Better investment | Fine if protein is already high |
If you're choosing one, go with EAAs. They include all 3 BCAAs plus the 6 other essentials your body needs to actually build muscle.
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Get early accessFrequently Asked Questions
EAAs vs BCAAs — which should I buy?
EAAs. BCAAs only give you 3 of the 9 essential amino acids, so they can't fully trigger muscle protein synthesis on their own. EAAs contain all 9, including the BCAAs. Unless you already eat plenty of protein and just want an intra-workout sip, EAAs are the better investment.
Do I need EAAs if I eat enough protein?
If you consistently hit 1.6–2.2 g/kg of protein from whole foods and whey, you probably don't need a separate EAA supplement. They're most useful for fasted training, low-protein diets, or people who struggle to eat enough protein from meals.
When is the best time to take EAAs?
During or right before your workout is the most common timing. If you train fasted, EAAs before or during training protect your muscles without spiking insulin the way a full meal would. You can also sip them throughout the day to bump up total amino acid intake.
Can EAAs replace whey protein?
Not really. Whey gives you all 9 EAAs plus calories, and it's cheaper per gram of protein. EAAs are lower calorie and absorb faster, which makes them better as a peri-workout supplement. Think of EAAs as a complement to whey, not a replacement.
How they work in your body
When you consume EAAs, leucine activates a pathway called mTOR (mechanistic target of rapamycin), which is the master switch for muscle protein synthesis. But here's the thing — leucine alone can flip the switch, but without the other 8 EAAs present, there aren't enough building blocks to actually complete the protein assembly. That's why BCAAs alone are less effective than a full EAA profile.
Free-form EAAs bypass the need for digestion (unlike whey or chicken), reaching your bloodstream in about 15–20 minutes. This makes them ideal for peri-workout use when you want rapid amino acid availability without a heavy stomach.
What the studies show
- MPS stimulation: 6 g of EAAs stimulated muscle protein synthesis as effectively as 20 g of whey in some studies (Paddon-Jones et al.)
- Muscle preservation: EAA supplementation during calorie restriction reduced lean mass loss by 25–30% vs placebo
- Recovery: Reduced muscle damage markers (CK) by 20–30% after resistance training
- Elderly benefit: Significant improvements in muscle mass and strength in older adults when combined with resistance training
Side effects & safety
EAAs are naturally found in every protein source you eat, so supplemental EAAs are very well tolerated:
- GI discomfort — Possible at very high doses (20 g+) or on an empty stomach. Start with 10 g and increase gradually.
- Bitter taste — Unflavoured EAAs taste terrible. Get a flavoured version or mix with juice.
- Amino acid imbalance — Not a concern at normal supplemental doses (10–15 g/day), but mega-dosing single amino acids long-term could theoretically compete for absorption.
Who should be cautious: People with maple syrup urine disease (MSUD) — a rare genetic condition — should avoid BCAA/EAA supplements. If you have kidney disease, check with your doctor before adding extra protein or amino acids.
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